Subjects -> PHYSICS (Total: 857 journals)
    - ELECTRICITY AND MAGNETISM (10 journals)
    - MECHANICS (22 journals)
    - NUCLEAR PHYSICS (53 journals)
    - OPTICS (92 journals)
    - PHYSICS (625 journals)
    - SOUND (25 journals)
    - THERMODYNAMICS (30 journals)

ELECTRICITY AND MAGNETISM (10 journals)

Showing 1 - 10 of 10 Journals sorted alphabetically
Advanced Electromagnetics     Open Access   (Followers: 15)
IEEE Electromagnetic Compatibility Magazine     Full-text available via subscription   (Followers: 14)
IEEE Journal of Electromagnetics, RF and Microwaves in Medicine and Biology     Hybrid Journal   (Followers: 1)
IEEE Letters on Electromagnetic Compatibility Practice and Applications     Hybrid Journal   (Followers: 1)
IEEE Transactions on Electromagnetic Compatibility     Hybrid Journal   (Followers: 30)
IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control     Hybrid Journal   (Followers: 8)
International Journal of Bioelectromagnetism     Open Access  
International Journal of Electromagnetics and Applications     Open Access   (Followers: 3)
Journal of Electroceramics     Hybrid Journal  
Magnetochemistry     Open Access  
Similar Journals
Journal Cover
Magnetochemistry
Number of Followers: 0  

  This is an Open Access Journal Open Access journal
ISSN (Online) 2312-7481
Published by MDPI Homepage  [249 journals]
  • Magnetochemistry, Vol. 9, Pages 34: Two-Dimensional Magnetotelluric
           Parallel-Constrained-Inversion Using Artificial-Fish-Swarm Algorithm

    • Authors: Hu, Shi, Liu, He, Xu, Mi, Liu
      First page: 34
      Abstract: An important way to improve the resolution of electromagnetic exploration is by using known seismic and logging data. Based on previous work, 2D magnetotelluric (MT) parallel-constrained-inversion, based on an artificial-fish-swarm algorithm is further developed. The finite-difference (FD) method with paralleling frequency is used for 2D MT-forward-modeling, to improve computational efficiency. The results of the FD and finite-element (FE) methods show that the accuracy of FD is comparable to FE in the case of suitable mesh-generation; however, the calculation speed is ten times faster than that of the FE. The artificial-fish-swarm algorithm is introduced and applied to parallel-constrained-inversion of 2D MT data. The results of the synthetic-model test show that the artificial-fish-swarm-inversion based on paralleling forward can recover the model well and effectively improve the inversion speed. The processing and interpretation results of the field data are verified by drilling, which shows that the proposed inversion-method has good practicability.
      Citation: Magnetochemistry
      PubDate: 2023-01-18
      DOI: 10.3390/magnetochemistry9020034
      Issue No: Vol. 9, No. 2 (2023)
       
  • Magnetochemistry, Vol. 9, Pages 35: Acknowledgment to the Reviewers of
           Magnetochemistry in 2022

    • Authors: Magnetochemistry Editorial Office Magnetochemistry Editorial Office
      First page: 35
      Abstract: High-quality academic publishing is built on rigorous peer review [...]
      Citation: Magnetochemistry
      PubDate: 2023-01-19
      DOI: 10.3390/magnetochemistry9020035
      Issue No: Vol. 9, No. 2 (2023)
       
  • Magnetochemistry, Vol. 9, Pages 36: Single-Molecule Magnets Based on
           Heteroleptic Terbium(III) Trisphthalocyaninate in Solvent-Free and
           Solvent-Containing Forms

    • Authors: Maxim A. Faraonov, Alexander G. Martynov, Marina A. Polovkova, Salavat S. Khasanov, Yulia G. Gorbunova, Aslan Yu. Tsivadze, Akihiro Otsuka, Hideki Yamochi, Hiroshi Kitagawa, Dmitri V. Konarev
      First page: 36
      Abstract: Binuclear heteroleptic triple-decker terbium(III) phthalocyaninate (Pc)Tb[(15C5)4Pc]Tb(Pc), where Pc2− is phthalocyaninate dianion and 15C5 is a 15-crown-5 moiety, has been synthesized as a solvent-free powder (1) and a well-defined crystal solvate with o-dichlorobenzene (Pc)Tb[(15C5)4Pc]Tb(Pc)⋅6C6H4Cl2 (2). In the crystal structure of 2, the Tb-N(Pc) distances to the nitrogen atoms in the outer and inner decks are 2.350–2.367(4) and 2.583–2.598(4) Å, respectively, and the Tb–Tb distance is 3.4667(3) Å. The twist angle between the outer and the inner decks is 42.6°. The magnetic properties were studied for both 1 and 2. The χMT magnitude of 23.3 emu⋅K/mol at 300 K indicates a contribution of two TbIII centers with the 7F6 ground state. The χMT product increases with decreasing temperature to reach 38.5 emu⋅K/mol at 2 K. This is indicative of ferromagnetic coupling between TbIII spins in accordance with previous data for triple-decker lanthanide phthalocyaninates of a dipolar nature. Both forms show a single-molecule magnet (SMM) behavior manifesting the in-phase (χ′) and out-of-phase (χ″) AC susceptibility signals in an oscillating field of 3 Oe with estimated effective spin-reversal energy barriers (Ueff) of 222(9) and 93(7) cm−1 for 1 and 2, respectively. The compounds show narrow hysteresis loops in the −1 – +1 kOe range, and the splitting between the zero-field-cooling and field-cooling curves is observed below 6 K. Thus, in spite of similar static magnetic characteristics, each form of the Tb(III) complex shows a different dynamic SMM behavior.
      Citation: Magnetochemistry
      PubDate: 2023-01-19
      DOI: 10.3390/magnetochemistry9020036
      Issue No: Vol. 9, No. 2 (2023)
       
  • Magnetochemistry, Vol. 9, Pages 37: Nanomaterial Endocytosis:
           Quantification of Adsorption and Ingestion Mechanisms

    • Authors: Abhinav Sannidhi, Chen Zhou, Young Suk Choi, Allan E. David, Paul W. Todd, Thomas R. Hanley
      First page: 37
      Abstract: The widespread use of nanomaterials in vaccines, therapeutics, and industrial applications creates an increasing demand for understanding their ingestion by living cells. Researchers in the field have called for a more robust understanding of physical/chemical particle–cell interactions and a means to determine the particles ingested per cell. Using superparamagnetic nanobeads, we measured the beads per cell and quantified the kinetics of the receptor-independent endocytosis of particles having seven surface chemistries. Poly(ethylene glycol) (PEG)-coated nanoparticles were ingested less effectively by cultured Chinese hamster ovary (CHO-K1) cells and more effectively by aminated nanoparticles than starch-coated particles. The cells ingested 2 to 4 × 105 of the most attractive particles. The interplay between Van der Waals and coulombic potentials was quantified on the basis of Derjaguin–Landau–Verwey–Overbeek (DLVO) theory modified to include hydration repulsion using physical parameters of the seven surface chemistries. Using dose–response curves for inhibitors of clathrin- or caveolae-dependent ingestion, we quantified how particle surface chemistry determines which endocytic pathway is used by the cell. Such characterization can be useful in predicting nanomaterial uptake in medical and toxicological applications and in the selection of particle surface chemistries for receptor-dependent endocytosis.
      Citation: Magnetochemistry
      PubDate: 2023-01-19
      DOI: 10.3390/magnetochemistry9020037
      Issue No: Vol. 9, No. 2 (2023)
       
  • Magnetochemistry, Vol. 9, Pages 38: Performance of Magnetic Fluid and Back
           Blade Combined Seal for Sealing Water

    • Authors: Hujun Wang, Zhongquan Gao, Xinzhi He, Zhenkun Li, Jinqiu Zhao, Zhuo Luo, Yaqun Wei
      First page: 38
      Abstract: When sealing liquids with magnetic fluid, the interfacial stability problem caused by the interaction between the magnetic fluid and the sealed liquid leads to poor sealing performance. Centrifugal force is generated by the rotation of the sealed liquid in the back blade seal, which forms back pressure to reduce the load of the seal or prevents the sealed liquid from leaking. To reduce the influence of the shaft speed on the sealing performance, a combined magnetic fluid and back blade seal was designed for sealing liquids and a combined seal experiment stand was set up. Theoretical and experimental studies were carried out. The results showed that under a higher shaft speed, the combined seal structure had better sealing performance in which the back blade seal played the main role; the magnetic fluid seal played a major role in stopping and lowering the speed to prevent seal leakage. The combined seal could run stably under different shaft speeds.
      Citation: Magnetochemistry
      PubDate: 2023-01-19
      DOI: 10.3390/magnetochemistry9020038
      Issue No: Vol. 9, No. 2 (2023)
       
  • Magnetochemistry, Vol. 9, Pages 39: Cluster Observation of Ion Outflow in
           Middle Altitude LLBL/Cusp from Different Origins

    • Authors: Bin Li, Huigen Yang, Jicheng Sun, Zejun Hu, Jianjun Liu, Xiangcai Chen, Yongfu Wang, Jie Ren, Chao Yue, C. Philippe Escoubet, Qian Wang, Qiugang Zong
      First page: 39
      Abstract: The ionosphere is the ionized part of the upper atmosphere that is caused mainly by photoionization by solar extreme ultraviolet (EUV) emission and the atmospheric photochemistry process. The ionospheric ions escape from the ionosphere and populate the Earth’s magnetosphere. In this case study, ion outflows from two different origins were obtained by spacecraft Cluster C1 in the magnetospheric cusp region. One of the outflows was from the reflection of the dispersed solar wind particles. The other was the ionospheric outflow passing through the low latitude boundary layer of the cusp (LLBL/cusp), which was energized by downward Poynting flux. Similar to the reflected solar wind particles, outflowing ionospheric cold ions could also extend to the high-latitude region with magnetic field line convection, which mixed it up with solar wind particles. Based on the Cluster observation in the cusp region, two different origins of the outflowing particles were determined, and their unique mechanisms of formation were discussed. Results suggest that the strong electric field associated with solar wind particle precipitation may additionally accelerate the cold ionospheric ion flow in the LLBL/cusp.
      Citation: Magnetochemistry
      PubDate: 2023-01-20
      DOI: 10.3390/magnetochemistry9020039
      Issue No: Vol. 9, No. 2 (2023)
       
  • Magnetochemistry, Vol. 9, Pages 40: Microstructural Model of Magnetic and
           Deformation Behavior of Single Crystals and Polycrystals of Ferromagnetic
           Shape Memory Alloy

    • Authors: Anatoli A. Rogovoy, Olga S. Stolbova
      First page: 40
      Abstract: In this article, a microstructural model of the Heusler alloy with the shape memory effect caused by the application of an external magnetic field is constructed. The dynamics of the magnetization process are described using the Landau–Lifshitz–Gilbert equation. For the numerical implementation of the model using the finite element method, the variational equations corresponding to the differential formulation of the magnetic problem are used. Such an approach makes it possible to reduce (weaken) the requirements for the smoothness of the sought solution. The problem of magnetization of single crystals of the Ni2MnGa alloy, which has a “herringbone”-type martensitic structure (a twinned variant of martensite), is considered. In each element of the twin, the magnetic domains with walls of a certain thickness are formed. The motion and interaction of these walls and the rotation of magnetization vector in the walls and domains under the action of the external differently directed magnetic fields are studied. These processes in the Heusler alloy are also accompanied by the detwinning process. A condition for the detwinning of a ferromagnetic shape memory alloy in a magnetic field is proposed, and the effect of the reorientation (detwinning) of martensitic variants forming a twin on the magnetization of the material and the occurrence of structural (detwinning) deformation in it are taken into account. First, the processes of magnetization and structural deformation in a single grain are considered at different angles between the anisotropy axes of twinned variants and the external magnetic field. For these cases, the magnetization curves are constructed, and the deformed states are identified. The model described such experimental facts as the detwinning process and the jump in magnetization on these curves as a result of this process. It was shown that the jump occurred at a certain magnitude of the strength of the applied external magnetic field and a certain direction of its action relative to the twinning system. Then, based on the obtained results, deformed states arising due to the detwinning process were determined for various (isotropic and texture-oriented) polycrystalline samples, and magnetization curves taking into account this process were constructed for these materials.
      Citation: Magnetochemistry
      PubDate: 2023-01-20
      DOI: 10.3390/magnetochemistry9020040
      Issue No: Vol. 9, No. 2 (2023)
       
  • Magnetochemistry, Vol. 9, Pages 17: Slow Magnetic Relaxation in Cobalt(II)
           Complexes with One-Dimensional Hydrogen-Bonded Networks

    • Authors: Ryoji Mitsuhashi, Hiroshi Sakiyama, Yoshihito Hayashi
      First page: 17
      Abstract: Two new cobalt(II) complexes with an unsymmetrical bidentate ligand, 2-(1,4,5,6-tetrahydropyrimidin-2-yl)-6-methoxyphenol (H2mthp), were synthesized and crystallographically characterized. Tetra- and hexa-coordinate mononuclear complexes were selectively obtained by adjusting the stoichiometry of the base. The coordination geometry of hexa-coordinated complex was severely distorted from an ideal octahedron, due to the NO5 coordination environment from the mixed coordination of one Hmthp− and two H2mthp ligands. Both complexes formed one-dimensional chain networks by hydrogen-bond and N-H···π interactions. Single-molecule magnet behavior was observed for the tetrahedral complex under zero magnetic field. The relatively short Co···Co distances induced non-zero intermolecular magnetic coupling, which split the ground ±Ms levels to suppress quantum-tunneling of magnetization. In the octahedral complex, by contrast, the distance was not short enough to induce the coupling. As a consequence, single-molecule magnetic behavior was observed for the octahedral complex only in the presence of an external static field.
      Citation: Magnetochemistry
      PubDate: 2023-01-01
      DOI: 10.3390/magnetochemistry9010017
      Issue No: Vol. 9, No. 1 (2023)
       
  • Magnetochemistry, Vol. 9, Pages 18: Impact of Silica-Modification and
           Oxidation on the Crystal Structure of Magnetite Nanoparticles

    • Authors: Artur Dzeranov, Lyubov Bondarenko, Denis Pankratov, Gulzhian Dzhardimalieva, Sharipa Jorobekova, Daniel Saman, Kamila Kydralieva
      First page: 18
      Abstract: At present, the widespread use of iron oxide nanoparticles, including for commercial purposes, requires strict preservation of their phase composition during their application. The choice of nanoparticle modifier and modification conditions is decisive due to their high sensitivity to oxygen in the case of using real conditions (O2, pH change, etc.). In this work, we studied the change in the phase composition of magnetite nanoparticles after modification with 3-aminopropyltriethoxysilane (APTES) and oxidation with nitric acid in order to estimate the protective potential of the silica shell. After modification by APTES and oxidation with nitric acid, the nonstoichiometric nature of the magnetite nanoparticles according to XRD data increased, which indicates an increase in transition forms compared to the initial sample (magnetite content decreased to 27% and 24%, respectively). In contrast, Mössbauer spectroscopy data detected a decrease in the nonstoichiometric index due to APTES modification conditions, but strong oxidation after exposure to nitric acid. It also showed that by analyzing the data of the diffraction analysis and Mössbauer spectroscopy for the same sample, one can obtain information not only about the ionic composition of “magnetite”, but also about the distribution of iron ions of different charges over the crystalline and amorphous parts of the preparation.
      Citation: Magnetochemistry
      PubDate: 2023-01-02
      DOI: 10.3390/magnetochemistry9010018
      Issue No: Vol. 9, No. 1 (2023)
       
  • Magnetochemistry, Vol. 9, Pages 19: Magnetizable Membranes Based on Cotton
           Microfibers, Honey, Carbonyl Iron, and Silver Nanoparticles: Effects of
           Static Magnetic Fields and Medium-Frequency Electric Fields on Electrical
           Properties

    • Authors: Ioan Bica, Eugen Mircea Anitas, Paula Sfirloaga
      First page: 19
      Abstract: In this work, we present the manufacturing process of magnetizable membranes based on cotton microfibers, honey, carbonyl iron, and three different concentrations of silver microparticles. Each membrane is used as a dielectric material for the fabrication of electrical devices. By using the plane capacitor method, the electrical capacitance and dielectric loss tangent are measured in a medium-frequency alternating field superimposed on a static magnetic field. From the obtained data, the time constants of the devices, the components of complex dielectric permittivity, and the electrical conductivity of the membranes as a function of the electric field frequency and magnetic flux density can be extracted. The results show that the obtained membranes can be useful for the fabrication of low-cost and environmentally friendly magneto-active membranes that are required for various technical and biomedical applications.
      Citation: Magnetochemistry
      PubDate: 2023-01-03
      DOI: 10.3390/magnetochemistry9010019
      Issue No: Vol. 9, No. 1 (2023)
       
  • Magnetochemistry, Vol. 9, Pages 20: Study of Defect-Induced Chemical
           Modifications in Spinel Zinc-Ferrites Nanostructures by In-Depth XPS
           Investigation

    • Authors: Promod Kumar, Mohan Chandra Mathpal, Gajendra Kumar Inwati, Sanjay Kumar, Mart-Mari Duvenhage, Wiets Daniel Roos, Hendrik C. Swart
      First page: 20
      Abstract: Spinel zinc ferrite nanomaterials with exceptional physiochemical properties are potential candidates for various applications in the energy and environmental fields. Their properties can be tailored using several methods to widen their applications. The chemical combustion approach was followed to prepare the spinel zinc ferrite nanomaterials, which were then subjected to thermal treatment at a fixed temperature. Thermal heat treatment at a fixed temperature was used to evaluate the phase and morphological characteristics of the prepared spinel zinc−ferrite nanocomposites. Various techniques were employed to examine the samples, including X−ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, and X−ray photoelectron spectroscopy (XPS). XPS and X−ray−induced Auger electron spectroscopy were used to extensively examine the surface characteristics of the zinc−ferrite. To study the actual chemical states of the synthesized spinel zinc ferrite nanomaterials and the defects created during the thermal treatment, an extensive investigation of the kinetic energy of the X−ray−induced Zn L3M45M45 and Fe L3M45M45 was conducted. Finally, a detailed analysis of the Wagner plot using the modified Auger parameter was performed to verify the exact chemical states of Zn and Fe. Thus, the findings of the investigation show that XPS is a promising and powerful technique to study the composition and chemical states of spinel zinc ferrites, providing an understanding of changes in their properties for functional applications.
      Citation: Magnetochemistry
      PubDate: 2023-01-03
      DOI: 10.3390/magnetochemistry9010020
      Issue No: Vol. 9, No. 1 (2023)
       
  • Magnetochemistry, Vol. 9, Pages 21: Surface Plasmon Resonance Biosensor
           Chip for Human Blood Groups Identification Assisted with
           Silver-Chromium-Hafnium Oxide

    • Authors: Purnendu Shekhar Pandey, Sanjeev Kumar Raghuwanshi, Rajesh Singh, Santosh Kumar
      First page: 21
      Abstract: Chromium (Cr), silver (Ag) and hafnium oxide (HfO2) are used in a surface plasmon resonance (SPR)-based biosensor with an optimized design for measuring blood groups at a wavelength of 633 nm. A buffer layer was placed on the SPR active metal in this investigation to avoid oxidation and contamination of blood samples. A theoretical model based on experimental data considered the refractive index of blood samples. The BK7 prism is the optimum substrate material for blood type identification analysis using a combination of Ag and Cr as an SPR active metal. The sensor’s performance is carefully researched in terms of its angular shift and curve width to predict the design aspects that provide precise blood-group identification. The SPR dip slope, detection accuracy and figure of merit (FOM) have been investigated concerning the subsequent generation of biosensor applications.
      Citation: Magnetochemistry
      PubDate: 2023-01-05
      DOI: 10.3390/magnetochemistry9010021
      Issue No: Vol. 9, No. 1 (2023)
       
  • Magnetochemistry, Vol. 9, Pages 22: Observations of Time-Domain Structures
           in the Plasmaspheric Plume by Van Allen Probes

    • Authors: Shangchun Teng, Huayue Chen, Qiang Zhang, Desheng Han
      First page: 22
      Abstract: Time-domain structures (TDS), manifested as ≥ 1 ms pulses with significant parallel electric fields, play an important role in accelerating electrons in the field-aligned direction. These precipitated electrons contribute to the formation of aurora. In this study, we present observations of time-domain structures that occurred in the plasmaspheric plumes at the post-midnight to dawn sector. The close correlation between TDS and plasmaspheric plumes implies that the generation of TDS might be modulated by plasma density. During the wave occurrence, protons with an energy level below 1 keV show the enhanced field-aligned pitch-angle distributions, and the electron fluxes with the energies ranging from tens to hundreds of eV are also significantly enhanced. The correlation between TDS and scattered particles indicates the importance of including time-domain structures in future studies of radiation belt dynamics.
      Citation: Magnetochemistry
      PubDate: 2023-01-05
      DOI: 10.3390/magnetochemistry9010022
      Issue No: Vol. 9, No. 1 (2023)
       
  • Magnetochemistry, Vol. 9, Pages 23: Recent Approaches in Magnetic
           Nanoparticle-Based Biosensors of miRNA Detection

    • Authors: Simge Balaban Hanoglu, Duygu Harmanci, Nursima Ucar, Serap Evran, Suna Timur
      First page: 23
      Abstract: In recent years, magnetic nanoparticles (MNPs) have been widely used in many fields due to their advantageous properties, such as biocompatibility, easy modifiability, and high chemical stability. One of these areas is the detection of cancer. It is essential to use existing biomarkers, such as microRNAs (miRNAs), for the early diagnosis of this disease. miRNAs are challenging to distinguish and detect in biological samples because they are small, circulating molecules. It is necessary to use more sensitive and feature-rich systems. Thanks to their large surface areas and magnetic moments, MNPs allow easy separation of miRNA at low concentrations from complex samples (urine and blood) and rapid and specific detection in biosensing systems. Here, we discussed the synthesis and characterization methods of MNPs, their stabilization, and MNP-based biosensors in terms of miRNA detection. We considered the challenges and prospects of these biosensor systems in evaluating the development stages, sensitivity, and selectivity.
      Citation: Magnetochemistry
      PubDate: 2023-01-06
      DOI: 10.3390/magnetochemistry9010023
      Issue No: Vol. 9, No. 1 (2023)
       
  • Magnetochemistry, Vol. 9, Pages 24: Relativistic Effects from Heavy Main
           Group p-Elements on the NMR Chemical Shifts of Light Atoms: From
           Pioneering Studies to Recent Advances

    • Authors: Irina L. Rusakova, Yuriy Yu. Rusakov
      First page: 24
      Abstract: This review represents a compendium of computational studies of relativistic effects on the NMR chemical shifts of light nuclei caused by the presence of heavy main group p-block elements in molecules. The narration starts from a brief discussion of the relativistic theories and quantum chemical methods for the calculation of NMR chemical shifts at the relativistic level of the electronic theory. The main part of the review contains a survey on the relativistic calculations of NMR shielding constants of the most popular NMR-active light nuclei such as 1H, 13C, 19F, 29Si, 15N, and 31P of compounds containing heavy p-elements. A special focus is placed on the relativistic effects initiated by the 16th and 17th group elements. Different factors governing the behavior of the relativistic effects on the chemical shifts of light atoms are discussed. In particular, the stereochemistry of the relativistic “heavy atom on the light atom” effect and the influence of the spin–orbit relativistic effects on the vibrational contributions to the shielding constants of light nuclei are considered.
      Citation: Magnetochemistry
      PubDate: 2023-01-07
      DOI: 10.3390/magnetochemistry9010024
      Issue No: Vol. 9, No. 1 (2023)
       
  • Magnetochemistry, Vol. 9, Pages 25: Structure and Magnetism of
           Iron-Substituted Nickel Hydroxide Nanosheets

    • Authors: Samuel W. Kimmel, Barry D. Koehne, Ben Gibson, Wilhelmus J. Geerts, Nikoleta Theodoropoulou, Christopher P. Rhodes
      First page: 25
      Abstract: Nanosheets composed of stacked atomic layers exhibit unique magnetic, electrical, and electrochemical properties. Here, we report the effect of iron substitution on the structure and magnetism of nickel hydroxide, Ni(OH)2, nanosheets. Ni(OH)2 and iron-substituted Ni(OH)2 (5, 10, 20, and 50 atomic % Fe substitution) were synthesized using a rapid microwave-assisted hydrothermal process. Scanning and transmission electron microscopy show the materials are polycrystalline nanosheets that aggregate into micron-sized clusters. From X-ray diffraction characterization, iron substitutes into the α-Ni(OH)2 lattice up to 20 at. % substitution. The nanosheets exhibit different in-plane and through-plane domain sizes, and Fe substitution affects the nanocrystallite shape anisotropy. The magnetic response differs with Fe substitution: 0% and 5% Fe are ferromagnetic, while samples with 10% and 20% Fe are ferrimagnetic. The competing interactions between magnetization sublattices and the magnetic anisotropy due to the crystalline and shape anisotropy of the nanosheets lead to magnetization reversal at low temperatures. The correlation between higher coercivity and larger nanocrystalline size anisotropy with higher Fe % supports that magnetic anisotropy contributes to the observed ferrimagnetism. The interplay of morphology and magnetic response with Fe-substituted Ni(OH)2 nanosheets points to new ways to influence electron interactions in layered materials which has implications for batteries, catalysis, sensors, and electronics.
      Citation: Magnetochemistry
      PubDate: 2023-01-08
      DOI: 10.3390/magnetochemistry9010025
      Issue No: Vol. 9, No. 1 (2023)
       
  • Magnetochemistry, Vol. 9, Pages 26: Magnetism and EPR Spectroscopy of
           Nanocrystalline and Amorphous TiO2: Fe upon Al Doping

    • Authors: Anatoly Yermakov, Mikhail Uimin, Kirill Borodin, Artem Minin, Danil Boukhvalov, Denis Starichenko, Alexey Volegov, Rushana Eremina, Ivan Yatsyk, Galina Zakharova, Vasiliy Gaviko
      First page: 26
      Abstract: This work is devoted to the study of the magnetic properties and Electron Paramagnetic Resonance (EPR) spectroscopy of TiO2:Fe nanoparticles doped with Al in different structural states. The sol-gel methods have been used to obtain the particles in both crystalline (average size from 3 to 20 nm) and X-ray amorphous states. The electron paramagnetic resonance spectra of crystalline samples TiO2:Fe doped with aluminum besides a resonance line with g-factor ~2 exhibit a small signal with a g-factor of 4.3 from Fe3+ ions with rhombohedral distortions. The fraction of Fe3+ with rhombohedral distortions increases with increasing aluminum content. For the amorphous state at Al doping, the resonance with a g-factor of 4.3 is completely dominant in the electron paramagnetic resonance spectrum. The density functional theory calculation shows that aluminum prefers to be localized near iron ions, distorting the nearest Fe3+ environment. The complex integral electron paramagnetic resonance spectrum of all samples was fitted with sufficient accuracy by three separate resonance lines with different widths and intensities. The temperature behavior of the electron paramagnetic resonance spectrum can be described by the coexistence of paramagnetic centers (isolated Fe3+ ions including dipole-dipole interactions) and iron clusters with negative exchange interactions.
      Citation: Magnetochemistry
      PubDate: 2023-01-09
      DOI: 10.3390/magnetochemistry9010026
      Issue No: Vol. 9, No. 1 (2023)
       
  • Magnetochemistry, Vol. 9, Pages 27: Giant Angular Nernst Effect in the
           Organic Metal α-(BEDT-TTF)2KHg(SCN)4

    • Authors: Danica Krstovska, Eun Sang Choi, Eden Steven
      First page: 27
      Abstract: We have detected a large Nernst effect in the charge density wave state of the multiband organic metal α-(BEDT-TTF)2KHg(SCN)4. We find that apart from the phonon drag effect, the energy relaxation processes that govern the electron–phonon interactions and the momentum relaxation processes that determine the mobility of the q1D charge carriers have a significant role in observing the large Nernst signal in the CDW state in this organic metal. The emphasised momentum relaxation dynamics in the low field CDW state (CDW0) is a clear indicator of the presence of a significant carrier mobility that might be the main source for observation of the largest Nernst signal. The momentum relaxation is absent with increasing angle and magnetic field, i.e., in the high-field CDW state (CDWx) as evident from the much smaller Nernst effect amplitude in this state. In this case, only the phonon drag effect and electron–phonon interactions are contributing to the transverse thermoelectric signal. Our findings advance and change previous observations on the complex properties of this organic metal.
      Citation: Magnetochemistry
      PubDate: 2023-01-10
      DOI: 10.3390/magnetochemistry9010027
      Issue No: Vol. 9, No. 1 (2023)
       
  • Magnetochemistry, Vol. 9, Pages 28: Mathematical and Physical Properties
           of Three-Band s± Eliashberg Theory for Iron Pnictides

    • Authors: Giovanni Alberto Ummarino
      First page: 28
      Abstract: The phenomenology of the iron pnictide superconductor can be described by the three-band s± Eliashberg theory in which the mechanism of superconducting coupling is mediated by antiferromagnetic spin fluctuations and whose characteristic energy Ω0 scales with Tc according to the empirical law Ω0=4.65kBTc. This model presents the universal characteristics that are independent of the critical temperature, such as the link between the two free parameters λ13 and λ23 and the ratio Δi/kBTc.
      Citation: Magnetochemistry
      PubDate: 2023-01-11
      DOI: 10.3390/magnetochemistry9010028
      Issue No: Vol. 9, No. 1 (2023)
       
  • Magnetochemistry, Vol. 9, Pages 29: Energetic Neutral Atom Imaging of the
           Earth’s Ring Current and Some Results from the Chinese Double Star
           Program

    • Authors: Zhiqing Chen, Chao Shen, Qiong Wu, Li Lu, Xianguo Zhang, Qinglong Yu
      First page: 29
      Abstract: The ring current region in the Earth’s magnetosphere contains energetic charged particles, which are injected from the magnetotail, get trapped in the inner magnetosphere, and finally drift around the Earth. The current, essentially carried by ions, is caused by the differences between the drift of the positively charged ions and that of negatively charged electrons. The charge exchange that occurs between ring current ions and geocoronal atoms determines the distribution and evolution of the ring current and lays the basis for remote detection techniques. By measuring the energetic neutral atoms produced by the charge-exchange process, the ring current can be remotely detected via energetic neutral atom imaging. The Chinese Double Star Program operated the NeUtral Atom Detector Unit (NUADU) onboard one of its two satellites for more than four years. A variety of studies were conducted using multiple methods applied to observations, such as intuitive image inspection, forward modeling, and inversion. Energetic neutral atom imaging was established as a promising technique for future imaging projects.
      Citation: Magnetochemistry
      PubDate: 2023-01-12
      DOI: 10.3390/magnetochemistry9010029
      Issue No: Vol. 9, No. 1 (2023)
       
  • Magnetochemistry, Vol. 9, Pages 30: New Manufacturing Process for Granular
           Texture Management in Polycrystalline BaM Hexaferrites through the
           Goethite Crystallite Laths Aspect Ratio, and a Specialized Law of Approach
           to the Magnetic Saturation for Partly Polarized Uniaxial Materials

    • Authors: Antoine Hoëz, Jean-Luc Mattei, Alexis Chevalier
      First page: 30
      Abstract: This study is aimed at the manufacture and the magnetic properties of polycrystalline M-type hexaferrites BaFe12O19 (barium ferrite, or BaM) materials of different magnetic texturing grades, going from a random distribution of the BaM crystallites to their almost complete stacking. Our target is to optimize the value of reduced-remanence magnetization MR/MS, which is among the most significant features of the self-polarized materials. In this study, we focus on the role played by the precursors hematite (isotropic spherical shape) and goethite (anisotropic lath shape). Therefore, 11 samples with a flat cylinder shape are fabricated, with an increasing hematite to goethite ratio. We demonstrate that this ratio drives the texturization of the samples by producing self-polarized materials with different MR/MS from the simple green compaction of the precursors, followed by a heat treatment. Most importantly, our study reveals the orientation of BaM particles after compaction; therefore, MR/MS, is strongly influenced by the aspect ratio of the lath-shaped goethite crystallites. Additionally, we show that finer goethite crystallites yield higher-value MR/MS. We optimize the aspect ratio of the goethite crystallites for an improved BaM texture. The optimization of the morphology of the goethite crystallites leads to an increase in the BaM particles’ orientation and stacking. The salient outcome of this work, which distinguishes it significantly from recent works, is that the particles stacking increases with the value of the shape factor η (defined as the ratio of the diameter of the laths to their length) of the goethite, evidenced by XRD results. The Rietveld refinements of powder diffractograms and the measured magnetic properties reveal a particle-stacking enhancement caused by not only the ratio of hematite: goethite but mainly by an optimal aspect ratio of the goethite crystallites. Based on this study, the BaM materials are further manufactured with a controlled magnetic texture; thus, they are partly self-polarized. They show reduced-remanence magnetization MR/MS varying from 0.5 and 0.81, while the angular dispersion of the BaM particles’ easy axis of magnetization varies from 60° to 10°. The magnetic properties of the samples are further studied in microwave experiments, from which the value of the magnetocrystalline anisotropy field HK = 16.6 kOe is deduced. The first magnetization curves of each sample are obtained using a VSM. A law of approach to the saturation suitable for the case of the uniaxial polycrystalline materials, and for which the particle stacking is only partial, is proposed for the fitting of the magnetization process. It is suggested that by using the proposed law with a known magnetocrystalline anisotropy constant K1, the angular grain-dispersion can be found.
      Citation: Magnetochemistry
      PubDate: 2023-01-12
      DOI: 10.3390/magnetochemistry9010030
      Issue No: Vol. 9, No. 1 (2023)
       
  • Magnetochemistry, Vol. 9, Pages 31: Something You Need Might Be under Your
           Feet: Molecular Magnetism of Heavy Kramers Lanthanide Hydrated Chlorides
           and Their Complexes with Polydentate Terpy Ligand

    • Authors: Svetlana P. Petrosyants, Konstantin A. Babeshkin, Andrey B. Ilyukhin, Pavel S. Koroteev, Nikolay N. Efimov
      First page: 31
      Abstract: A study of the molecular magnetism of the hydrated salts [Ln(H2O)6Cl2]Cl (Ln = Gd (1Gd), Dy (1Dy), Er (1Er), Yb (1Yb)) and lanthanide chloride complexes with 2,2′;6′,2″-terpyridine (terpy) synthesized on their basis, [Ln(H2O)4(terpy)Cl]Cl2·3H2O (Ln = Gd (2Gd), Dy (2Dy), Er (2Er), and Yb (2Yb), was carried out. It was found that both the initial hydrated chlorides containing Dy, Er, Yb, and their derivatives with terpyridine exhibit the properties of single-molecule magnets. For the complexes with terpyridine, the values of the remagnetization barriers increase from Er to Dy, while for the aquachlorides, the corresponding values increase in the series Ueff (1Dy) < Ueff (1Er). It was found that magnetic relaxation in Yb complexes mostly proceeds according to the Raman mechanism.
      Citation: Magnetochemistry
      PubDate: 2023-01-12
      DOI: 10.3390/magnetochemistry9010031
      Issue No: Vol. 9, No. 1 (2023)
       
  • Magnetochemistry, Vol. 9, Pages 32: Hydrogeological Study in Tongchuan
           City Using the Audio-Frequency Magnetotelluric Method

    • Authors: Xu, Xin, Weng, Li
      First page: 32
      Abstract: Tongchuan City, located in Shaanxi Province, northwest China, has limited groundwater resources. Rational planning and exploitation of groundwater are crucial to the sustainable development of the city, for which investigating the distribution of groundwater is the premise. Traditional resistivity sounding methods are often used to detect groundwater; however, these methods are not applicable in the study area where thick Quaternary loess is extensively distributed. In this study, we arranged five audio-frequency magnetotelluric (AMT) profiles to detect the deep clastic rock groundwater and carbonate karst fissure groundwater in Tongchuan. Firstly, we analyzed the electromagnetic interference (EMI) noises in Tongchuan City, revealing that the main EMI is power frequency interference (PFI). We used the dictionary learning processing technology to suppress the PFI. Secondly, the two-dimensional (2D) nonlinear conjugate gradient method was employed to invert a 2D electrical structure model for the area shallower than 1 km. We analyzed the characteristics of the electrical structure and its geological significance. Lastly, the three-dimensional (3D) electrical structure model of the study area was inverted using the 3D nonlinear conjugate gradient method, and the spatial distribution characteristics of the water-bearing strata were further analyzed. The results show that the PFI in urban environment can be suppressed by the dictionary learning processing technology. In Tongchuan city, the distribution of clastic rock fissure water is controlled by folds and faults, as well as the thickness of sandstone layers, and that of the carbonate karst fissure water is mainly controlled by faults. On this basis, we infer that the water-bearing areas are in the middle east and south of the study area.
      Citation: Magnetochemistry
      PubDate: 2023-01-14
      DOI: 10.3390/magnetochemistry9010032
      Issue No: Vol. 9, No. 1 (2023)
       
  • Magnetochemistry, Vol. 9, Pages 33: Slow Methyl Axes Motions in
           Perdeuterated Villin Headpiece Subdomain Probed by Cross-Correlated NMR
           Relaxation Measurements

    • Authors: Liliya Vugmeyster, Parker J. Nichols, Dmitry Ostrovsky, C. James McKnight, Beat Vögeli
      First page: 33
      Abstract: Protein methyl groups can participate in multiple motional modes on different time scales. Sub-nanosecond to nano-second time scale motions of methyl axes are particularly challenging to detect for small proteins in solutions. In this work we employ NMR relaxation interference between the methyl H-H/H-C dipole-dipole interactions to characterize methyl axes motions as a function of temperature in a small model protein villin headpiece subdomain (HP36), in which all non-exchangeable protons are deuterated with the exception of methyl groups of leucine and valine residues. The data points to the existence of slow motional modes of methyl axes on sub-nanosecond to nanosecond time scales. Further, at high temperatures for which the overall tumbling of the protein is on the order of 2 ns, we observe a coupling between the slow internal motion and the overall molecular tumbling, based on the anomalous order parameters and their temperature-dependent trends. The addition of 28% (w/w) glycerol-d8 increases the viscosity of the solvent and separates the timescales of internal and overall tumbling, thus permitting for another view of the necessity of the coupling assumption for these sites at high temperatures.
      Citation: Magnetochemistry
      PubDate: 2023-01-14
      DOI: 10.3390/magnetochemistry9010033
      Issue No: Vol. 9, No. 1 (2023)
       
  • Magnetochemistry, Vol. 9, Pages 1: Research on Modification of Fe3O4
           Magnetic Nanoparticles with Two Silane Coupling Agents

    • Authors: Hongchao Cui, Jiajia Zhang, Jingjing Lu, Zhenkun Li, Decai Li
      First page: 1
      Abstract: As a novel functional nanomaterial, Fe3O4 magnetic nanoparticles (MNPs) modified by different surfactants have attracted and are attracting worldwide interest. In this research, we introduced two different silane coupling agents to modify Fe3O4 MNPs instead of a single surfactant to achieve complete coating and functionalization. The modification mechanism was also explained. Techniques such as TEM, XRD, FT-IR, TG-DSC, and VSM were applied to characterize the obtained modified Fe3O4 sample. From these techniques, the following information is obtained: The characteristic bands of TEOS and KH-792 were present in the FT-IR spectra and in the XPS plots of modified Fe3O4 MNPs, demonstrating that the silane coupling agents were present in the sample obtained after the modification. The TG analysis of the modified sample showed complete decomposition at 228°C. The mass ratio of the sample obtained before and after the modification was close to 29:65. The XRD patterns show that the modified Fe3O4 MNPs possessed an identical reverse spinel crystal structure as an unmodified Fe3O4 sample. The modification decreased the saturation magnetization of Fe3O4 MNPs from 70.04 emu/g to 57.41 emu/g and the coating did not change the superparamagnetism of Fe3O4 MNPs.
      Citation: Magnetochemistry
      PubDate: 2022-12-21
      DOI: 10.3390/magnetochemistry9010001
      Issue No: Vol. 9, No. 1 (2022)
       
  • Magnetochemistry, Vol. 9, Pages 2: Effect of Infill Density of the Printed
           PET-G Structures Containing Iron Oxides on Magnetic Properties

    • Authors: Lucie Zárybnická, Martin Marek, Radek Ševčík, Radek Stolín, Jaroslav Pokorný, Jiří Šál
      First page: 2
      Abstract: This work aims to characterize printing structures with various infill densities composed of a thermoplastic material containing magnetic particles composed of mainly Iron(III) oxides with regard to their possible processing with the additive technology of Fused Filament Fabrication. A polyethylene terephthalate glycol (PET-G) structural thermoplastic with the addition of Iron(III)) oxides has been selected, and correct processing temperatures have been determined using thermal analysis. The paramagnetic properties of printed products consisting of different filling densities have been tested. Relative permeability has been identified to be strongly dependent on the printed internal structures of tested products. The samples composed of the densest structure have shown relative permeability higher by 18% with respect to the sample printed with the least dense structure. Finite Element Modelling (FEM) simulations have been applied to determine magnetic field distributions and, moreover, to calculate the holding forces of all printed samples. The performed simulations confirmed that produced composites might be utilized as magnetic switches and sensors or as more advanced components for homogenizing electric motors’ magnetic fields. Moreover, magnetic properties might be tuned according to the specific needs printing structure with the suitable density.
      Citation: Magnetochemistry
      PubDate: 2022-12-22
      DOI: 10.3390/magnetochemistry9010002
      Issue No: Vol. 9, No. 1 (2022)
       
  • Magnetochemistry, Vol. 9, Pages 3: Iron Oxides Nanoparticles as Components
           of Ferroptosis-Inducing Systems: Screening of Potential Candidates

    • Authors: Artur Dzeranov, Lyubov Bondarenko, Denis Pankratov, Mikhail Prokof‘ev, Gulzhian Dzhardimalieva, Sharipa Jorobekova, Nataliya Tropskaya, Ludmila Telegina, Kamila Kydralieva
      First page: 3
      Abstract: This study presents an analysis of a set of iron oxides nanoparticles (NPs) (γ-Fe2O3, α-FeOOH, δ-FeOOH, 5Fe2O3·9H2O, and Fe3O4) as potential candidates for ferroptosis therapy in terms of a phase state, magnetic characteristics, and the release of Fe2+/Fe3+ as ROS mediators. Due to the values of saturation magnetization for Fe3O4 (31.6 emu/g) and γ-Fe2O3 (33.8 emu/g), as well as the surface area of these particles (130 and 123 m2/g), it is possible to consider them as promising magnetically controlled carriers that can function with various ligands. The evaluation of the release of Fe2+/Fe3+ ions as catalysts for the Fenton reaction showed that the concentration of the released ions increases within first 3 h after suspension and decreases within 24 h, which probably indicates desorption and adsorption of ions from/onto the surface of nanoparticles regardless their nature. The concentration of ions released by all nanoparticles, except α-FeOOH-Fe2+, reached 9.1 mg/L for Fe3+ to 1.7 mg/L for Fe2+, which makes them preferable for controlling the catalysis of the Fenton reaction. In contrast, a high concentration of iron ions to 90 mg/L for Fe3+ and 316 mg/L for Fe2+ released from compound α-FeOOH-Fe2+ allows us to utilize this oxide as an aid therapy agent. Results obtained on iron oxide nanoparticles will provide data for the most prospective candidates that are used in ferroptosis-inducing systems.
      Citation: Magnetochemistry
      PubDate: 2022-12-23
      DOI: 10.3390/magnetochemistry9010003
      Issue No: Vol. 9, No. 1 (2022)
       
  • Magnetochemistry, Vol. 9, Pages 4: The Assembly of Grid-type Lanthanide
           Cluster

    • Authors: Jinsong Li, Fan Zhang, Xuefeng Guo, Dan Liu, Jianfeng Wu
      First page: 4
      Abstract: A dicompartmental Schiff base ligand was synthesized and used for the assembly of a lanthanide grid-like complex. Dinuclear Dy2 and tetranuclear Dy4 complexes were isolated from the reaction of the ligand with different dysprosium salt. Single crystal X-ray diffractions show that the two DyIII ions in Dy2 are adopted in the N3O coordination pockets of the ligand and further coordinated by water molecules, whereas, for Dy4, the four DyIII ions are clamped by four ligands through their terminal N3O coordination pockets, forming a grid-type assembly. Magnetic studies reveal that complex Dy2 shows field-induced single-molecule magnetic behavior under 1000 Oe dc field, complex Dy4 shows fast relaxation under zero field and field-induced single-molecule magnet (SMM) behavior under 500 Oe. The difference in the magnetic relaxation is related to the various deprotonation of the ligand and distinct topology of the assemblies.
      Citation: Magnetochemistry
      PubDate: 2022-12-24
      DOI: 10.3390/magnetochemistry9010004
      Issue No: Vol. 9, No. 1 (2022)
       
  • Magnetochemistry, Vol. 9, Pages 5: Superparamagnetic-like Micrometric
           Single Crystalline Magnetite for Biomedical Application Synthesis and
           Characterization

    • Authors: Marius Chirita, Adrian Bezergheanu, Corneliu Bazil Bazil Cizmas, Aurel Ercuta
      First page: 5
      Abstract: Single-crystalline magnetite (Fe3O4) particles having a size beyond the nanometric range (1 µm to 50 µm) and showing high (close to the bulk value) saturation-specific magnetization (σs = 92 emu/g), were obtained by the hydrothermal decomposition of the Fe-EDTA complex. The very low values of the magnetic remanence (σr = 0.82 emu/g) and coercitivity (μoHc = 1.53 mT) observed at room temperature (RT) suggest a superparamagnetic-like behavior, which is quite remarkable for such micrometric magnetite particles. As confirmed by vibrating sample magnetometer (VSM)-based measurements, minor changes in their magnetic properties occur between RT and 5K. Scanning electron microscopy (SEM) has revealed a morphology consisting of a combination of non-porous octahedral- and dodecahedral-shaped particles, energy dispersive X-ray analysis (EDX) has indicated high elemental (Fe and O) purity, whereas X-ray diffraction (XRD) has confirmed a single crystal structure. The nitrogen adsorbtion–desorption isotherm and pore size distribution are presented for the magnetite sample. Thermomagnetic records under zero field-cooled (ZFC) and field-cooled (FC) conditions have revealed a thermal hysteresis of the Verwey transition.The Verwey point (TV) at which the major step of the phase transformation takes place is located around 132 K for heating and around 122 K for cooling. These microcrystals do not remain agglomerated when the polarizing field is removed, an essential requirement in biomedical applications is met.
      Citation: Magnetochemistry
      PubDate: 2022-12-24
      DOI: 10.3390/magnetochemistry9010005
      Issue No: Vol. 9, No. 1 (2022)
       
  • Magnetochemistry, Vol. 9, Pages 6: Old Discovery Leading to New Era:
           Metabolic Imaging of Cancer with Deuterium MRI

    • Authors: Hao Ding, Athar Haroon, Simon Wan, Thoralf Niendorf, Sola Adeleke
      First page: 6
      Abstract: The understanding of metabolic compartments involved in the survival, growth and invasion of tumours is important for modern cancer research. Deuterium metabolic spectroscopy (DMS) and metabolic imaging (DMI) have been demonstrated as robust, straightforward tools for visualising tumour metabolism in vivo. However, for them to become part of the cancer patient’s management pathway in a clinical setting, there remain many obstacles to overcome. Technological advancement in magnetic resonance imaging hardware and processing is needed. Further justification of DMI’s potential also requires more human study and multidisciplinary collaboration.
      Citation: Magnetochemistry
      PubDate: 2022-12-25
      DOI: 10.3390/magnetochemistry9010006
      Issue No: Vol. 9, No. 1 (2022)
       
  • Magnetochemistry, Vol. 9, Pages 7: Kinetics and the Effect of Thermal
           Treatments on the Martensitic Transformation and Magnetic Properties in
           Ni49Mn32Ga19 Ferromagnetic Shape Memory Ribbons

    • Authors: Felicia Tolea, Bogdan Popescu, Cristina Bartha, Monica Enculescu, Mugurel Tolea, Mihaela Sofronie
      First page: 7
      Abstract: In our work, the kinetics of martensitic transformations and the influence of thermal treatments on martensitic transformations, as well as the related magnetic properties of the Ni49Mn32Ga19 ferromagnetic shape memory melt-spun ribbons, have been investigated. Thermal treatments at 673 K for 1, 4 and 8 h can be considered an instrument for fine-tuning the performance parameters of alloys. One-hour thermal treatments promote an improvement in the crystallinity of these otherwise highly textured ribbons, reducing internal defects and stress induced by the melt-spinning technique. Longer thermal treatments induce an important magnetization rise concomitantly with a slight and continuous increase in martensitic temperatures and transformation enthalpy. The activation energy, evaluated from differential scanning calorimeter experimental data with a Friedman model, significantly increases after thermal treatments as a result of the multi-phase coexistence and stabilization of the non-modulated martensitic phase, which increases the reverse martensitic transformation hindrance.
      Citation: Magnetochemistry
      PubDate: 2022-12-25
      DOI: 10.3390/magnetochemistry9010007
      Issue No: Vol. 9, No. 1 (2022)
       
  • Magnetochemistry, Vol. 9, Pages 8: Evidence of Hysteresis Free
           Ferromagnetic Nature and Significant Magnetocaloric Parameters in FeNi
           Binary Alloy

    • Authors: Mohit K. Sharma, Akshay Kumar, Kavita Kumari, Su-Jeong Park, Naveen Yadav, Seok-Hwan Huh, Bon-Heun Koo
      First page: 8
      Abstract: In this study, our aim is to investigate the structural, magnetic, and magnetocaloric properties of the FeNi binary alloy. The FeNi alloy with Fe65Ni35 composition was prepared by ball milling followed by the annealing and quenching processes. A Rietveld refinement analysis of structural results reveals that this system has coexisting cubic structural phases with a dominant face-centered cubic phase (Fm-3m;γ-FeNi). Magnetization results of this compound indicate the presence of ferromagnetic ordering and the magnetic transition observed around 100 K. Moreover, an Arrott plot study provides information about the order of phase transition, which is found in the second-order near the ordering temperature, whereas first-order nature is also noted in the low-temperature region. The significant magnetocaloric parameters, i.e., magnetic entropy change (ΔSM~0.495 J/kg-K) and relative cooling power (88 J/kg), are noted over a wide temperature range. The power law dependency of magnetic entropy change with the applied field is also investigated. Due to their significant magnetocaloric performance over a wide temperature range, these multiphase alloys may be a good candidate for room-temperature to low-temperature magnetic refrigeration.
      Citation: Magnetochemistry
      PubDate: 2022-12-26
      DOI: 10.3390/magnetochemistry9010008
      Issue No: Vol. 9, No. 1 (2022)
       
  • Magnetochemistry, Vol. 9, Pages 9: Levofloxacin Adsorption onto
           MWCNTs/CoFe2O4 Nanocomposites: Mechanism, and Modeling Using Non-Linear
           Kinetics and Isotherm Equations

    • Authors: Tariq J. Al-Musawi, Yasir Qasim Almajidi, Ethar M. Al-Essa, Rosario Mireya Romero-Parra, Enas R. Alwaily, Nezamaddin Mengelizadeh, Fatemeh Ganji, Davoud Balarak
      First page: 9
      Abstract: In the present work, the adsorption mechanism and capacity of MWCNTs/CoFe2O4 nanocomposite as an adsorbent were investigated. Levofloxacin (LFX), a widely used antibiotic, was selected as a hazardous model contaminant in aqueous solutions. The surface and inner characterization of MWCNTs/CoFe2O4 was obtained via SEM/TEM, XRD, BET/BJH, and pHPZC. These analyses indicated that MWCNTs/CoFe2O4 possess excellent surface and pore characteristics, e.g., specific surface area, pore volume, and mean pore diameter, which were 72 m2/g, 0.51 cm3/g, and 65 nm, respectively. The results demonstrate that by supplementing 1 g/L of MWCNTs/CoFe2O4 at experimental conditions of pH value of 5, temperature of 30 °C, initial LFX concentration of 50 mg/L and mixing time of 90 min, a significant outcome of 99.3% removal was achieved. To identify the phenomenon of adsorption, the thermodynamic parameters of ΔH° and ΔS° were calculated, which indicated that the nature of LFX adsorption onto MWCNTs/CoFe2O4 nanocomposite was endothermic and spontaneous. Nine isotherm models, including four two-parameter and five three-parameter models, were investigated. In addition, the regression coefficient as well as five error coefficient models were calculated for nonlinear isotherm models. According to the goodness of fit tests, the equilibrium data were well coordinated with the Freundlich and Sips isotherms. The kinetics study showed that the LFX adsorption data well fitted with pseudo-second-order model, and the adsorption of LFX molecules occurred through several stages from surface to intraparticle diffusion. In conclusion, the present work evinces that LFX wastewater can be efficiently treated via an adsorption process using a MWCNTs/CoFe2O4 nanocomposite.
      Citation: Magnetochemistry
      PubDate: 2022-12-27
      DOI: 10.3390/magnetochemistry9010009
      Issue No: Vol. 9, No. 1 (2022)
       
  • Magnetochemistry, Vol. 9, Pages 10: Influence of the Preparation Technique
           on the Magnetic Characteristics of ε-Fe2O3-Based Composites

    • Authors: Dmitriy O. Testov, Kamil G. Gareev, Ivan K. Khmelnitskiy, Andrei Kosterov, Leonid Surovitskii, Victor V. Luchinin
      First page: 10
      Abstract: ε-Fe2O3 is an iron(III) oxide polymorph attracting an increasing interest due to its unique magnetic properties combining extremely high coercivity and relatively large saturation magnetization. We review existing methods for the ε-Fe2O3 synthesis focusing on synthesis speed, repeatability, manufacturability and purity of the final product. Samples of ε-Fe2O3 have been synthesized using the two methods that appear the most promising: silica gel impregnation and microemulsion. In both cases, ε-Fe2O3 and α-Fe2O3 are present in the final product as attested by X-ray diffraction patterns and magnetic properties (maximum coercive force at 300 K~1 Tesla). Two different precursors, iron(III) nitrate and iron(II) sulfate, have been used in the silica gel impregnation method. Somewhat surprisingly, iron sulfate proved superior yielding ε-Fe2O3 content of 69% in the total iron oxide product, compared to 25% for iron nitrate under the same synthesis conditions. These results pave the way for modifying the existing ε-Fe2O3 synthesis methods aiming to increase the content of the epsilon phase in the final product and, consequently, improve its physicochemical properties.
      Citation: Magnetochemistry
      PubDate: 2022-12-28
      DOI: 10.3390/magnetochemistry9010010
      Issue No: Vol. 9, No. 1 (2022)
       
  • Magnetochemistry, Vol. 9, Pages 11: Up-Conversion Luminescence and
           Magnetic Properties of Multifunctional Er3+/Yb3+-Doped SiO2-GdF3/LiGdF4
           Glass Ceramics

    • Authors: Corina Secu, Cristina Bartha, Cristian Radu, Mihail Secu
      First page: 11
      Abstract: Glassy nanocomposites containing Yb3+/Er3+-doped GdF3 and LiGdF4 nanocrystals have been prepared by controlled crystallization of the xerogel and the structural, up-conversion luminescence, and magnetic properties were analyzed and discussed. Structural and morphological analysis showed uniform distribution of both GdF3 and LiGdF4 nanocrystals (tens of nm size), embedded in silica glass matrix as the result of thermal decomposition of the trifluoracetates, revealed as a strong exothermic peak at about 300 °C; the Li-ions co-doping showed a strong influence on the GdF3 and LiGdF4 nanocrystalline fraction. The energy dispersive spectrometry mapping showed Gd, F and Yb, Er within the nanocrystals but not in the silica glass matrix. X-ray diffraction pattern analysis indicated the crystalline lattice distortion consistent with the Yb/Er incorporation in both fluoride nanocrystals. The “green” ((2H11/2, 4S3/2) →4I15/2) and “red” (4F9/2→4I15/2) up-conversion luminescences at 525, 545, and 660 nm observed under 980 nm laser light pumping were assigned to the Er3+ ions deexcitation through a two-photon process. The magnetic properties of the nanocomposite are strongly temperature dependent. The magnetization hysteresis loops show a ferromagnetic behavior at low temperatures (5K) related to the rare-earth ions contribution and the saturation magnetization of 39 emu/g. At 300 K a paramagnetic behavior was observed that was ascribed to the non-interacting localized nature of the magnetic moment of the rare-earth ions. Hence, such novel, multifunctional magnetic and optical materials can allow the intertwining between magnetism and photonics and might offer new opportunities for new magneto-optical device development.
      Citation: Magnetochemistry
      PubDate: 2022-12-29
      DOI: 10.3390/magnetochemistry9010011
      Issue No: Vol. 9, No. 1 (2022)
       
  • Magnetochemistry, Vol. 9, Pages 12: Magnetic Nanocomposites and Imprinted
           Polymers for Biomedical Applications of Nucleic Acids

    • Authors: Victoriya Popova, Elena Dmitrienko, Alexey Chubarov
      First page: 12
      Abstract: Magnetic nanocomposites (MNCs) combine the features of magnetic nanoparticles and a second material, which provide distinct physical, chemical, and biological properties. The magnetic core for nanocomposite synthesis is extensively used due to its high saturation magnetization, chemical stability, large surface area, and easy functionalization. Moreover, magnetic nanoparticles (MNPs) have great potential for magnetic resonance imaging (MRI), magnetic particle imaging (MPI), hyperthermia, and targeted drug and gene delivery by an external magnetic field. Numerous composing units exist, which leads to the outstanding application of composites. This review focuses on nucleic acid-based bioapplications of MNCs with polymeric, organic, inorganic, biomolecules, and bioinspared surface coating. In addition, different forms, such as core–shell, doping, multilayer, yolk–shell, and Janus-shaped hybrids, are discussed, and their unique properties are highlighted. The unique types of nanocomposites as magnetic molecularly imprinted polymer (MMIP) properties are presented. This review presents only the synthesis of MNCs using ready-made magnetic cores. These restrictions are associated with many materials, the quantitative and qualitative magnetic core composition, and synthesis procedures. This review aims to discuss the features of nucleic acid-based MNC information available to researchers in this field and guide them through some problems in the area, structure variation, and surface functionalization possibilities. The most recent advancements of MNCs and imprinted polymers in nucleic acid-based therapy, diagnostics, theranostics, magnetic separation, biocatalytic, and biosensing are introduced.
      Citation: Magnetochemistry
      PubDate: 2022-12-30
      DOI: 10.3390/magnetochemistry9010012
      Issue No: Vol. 9, No. 1 (2022)
       
  • Magnetochemistry, Vol. 9, Pages 13: Interrelation between the Solid-State
           Synthesis Conditions and Magnetic Properties of the NiCr2O4 Spinel

    • Authors: Mikhail Cherosov, Ruslan Batulin, Airat Kiiamov, Alexey Rogov, Iskander Vakhitov, Damir Gabadullin, Dmitrii Tayurskii, Roman Yusupov
      First page: 13
      Abstract: The synthesis of the NiCr2O4 compound with the spinel structure via the high-temperature solid-state reaction leads to different deviations of the cationic composition from the nominal depending on the atmosphere in the furnace chamber. The samples prepared from the same starting NiO and Cr2O3 compounds but in different atmospheres differ in phase composition and orbital and spin ordering temperatures. We find that a common route of synthesis in the air and a possible presence of the Ni2O3 in initial NiO lead to the incorporation of the Ni3+ ions into the octahedral sites regularly occupied by the Cr3+ ions. This results in a decrease in the orbital ordering and an increase in the Nèel temperatures. We propose that the Nèel temperature value serves as a measure of a departure of a composition from the nominal NiCr2O4. The lowest Nèel temperature among our series was TN = 63 K which we consider the closest to the intrinsic quantity of the NiCr2O4 compound.
      Citation: Magnetochemistry
      PubDate: 2022-12-30
      DOI: 10.3390/magnetochemistry9010013
      Issue No: Vol. 9, No. 1 (2022)
       
  • Magnetochemistry, Vol. 9, Pages 14: Crystal Structures and Magnetic
           Properties of Diaquatetrapyridinenickel(II) and
           Diaquatetrapyridinecobalt(II) Complexes

    • Authors: Sakiyama, Yamamoto, Hoshikawa, Mitsuhashi
      First page: 14
      Abstract: Metal complexes with pyridine ligands (py) have not been crystallographically characterized in large numbers, while a large number of 2,2′-bipyridine (bpy) complexes have been structurally characterized. Against this background of scarcity of py complexes, the aim of this study was to characterize the structures and magnetic properties of complexes with pyridine ligands. In this study, new py complexes, trans-[Ni(H2O)2(py)4][BPh4]2·4py (1) and trans-[Co(H2O)2(py)4][BPh4]2·4py (2), were prepared and characterized by the single-crystal X-ray diffraction method and magnetic measurements. In the crystal structure analysis, both complexes were found to have octahedral trans-N2O4 coordination geometry, and the coordination of the trans-aqua ligands was found to be enhanced by the hydrogen-bonded pyridine molecules as a base. In the simultaneous analysis of magnetic susceptibility and magnetization, both complexes were found to show strong magnetism in one direction (χz > χx, χy; Mz > Mx, My), and this was explained by the enhancement of the axial aqua ligands. In the nickel(II) complex, the strong axial ligand field was found to cause negative zero-field splitting (D < 0) to show the magnetic behavior, while in the cobalt(II) complex, the strong axial π-orbital effect was found to cause negative ligand field splitting (Δ) in the 4T1 ground state to show the magnetic behavior.
      Citation: Magnetochemistry
      PubDate: 2022-12-30
      DOI: 10.3390/magnetochemistry9010014
      Issue No: Vol. 9, No. 1 (2022)
       
  • Magnetochemistry, Vol. 9, Pages 15: The Study of Structural Features of N-
           and O-Derivatives of 4,5-Dihydroxyimidazolidine-2-Thione by NMR
           Spectroscopy and Quantum Chemical Calculations

    • Authors: Liudmila E. Kalichkina, Alexander V. Fateev, Polina K. Krivolapenko, Kristina A. Isakova, Alexey S. Knyazev, Victor S. Malkov, Abdigali A. Bakibaev, Vera P. Tuguldurova
      First page: 15
      Abstract: In the present work, the new N-methylol and O-alkyl derivatives of 4,5-dihydroxyimidazolidine-2-thione (DHIT) are synthesized. The effects of N-alkyl, N-phenyl, N-methylol, and O-alkyl substituents of DHIT on the 13C and 1H signals in NMR spectra of the imidazolidine-2-thione ring are systematized using quantum chemical calculations. The shift values of carbon and hydrogen atoms are specific for the geometric isomers of the indicated DHIT derivatives. The chemical shifts of the carbon atoms of the methine groups allows for identifying the cis and trans isomers of the N-alkyl derivatives of DHIT due to the up-field shifts of the cis isomers. The introduction of an alkyl substituent at the N-position of the imidazolidine-2-thione ring leads to the up-field shifts of the carbon atoms of the ring due to the inductive effects of these groups. The ring current effect in the N-phenyl derivatives of DHIT that affects the positions of the carbon signals of the imidazolidine-2-thione ring has been found. The N-methylol derivatives of 4,5-dihydroxyimidazolidine-2-thione have been identified for the first time using 1D and 2D NMR.
      Citation: Magnetochemistry
      PubDate: 2022-12-31
      DOI: 10.3390/magnetochemistry9010015
      Issue No: Vol. 9, No. 1 (2022)
       
  • Magnetochemistry, Vol. 9, Pages 16: Magnetic-Moment-Induced
           Metal–Insulator Transition in ThMnXN (X = As, P): A First Principles
           Study

    • Authors: Smritijit Sen, Haranath Ghosh
      First page: 16
      Abstract: In this work, we show magnetic-moment-induced metal–insulator transitions in ThMnXN (X = As, P) and elucidate some of the experimentally observed results obtained by Zhang et al. through a first principles density functional study. Our calculations revealed that the magnetic ground states of ThMnXN (X = As, P) are C-type anti-ferromagnets with a small energy gap (∼0.4 eV) at the Fermi level, which is in good agreement with the experiments. Our constraint moment calculations revealed local magnetic moments of 3.42 μB and 3.63 μB in Mn atoms for ThMnAsN and ThMnPN, respectively, which are consistent with the experimentally measured local magnetic moment for Mn atoms. An effective Hubbard U = (U − J) of 0.9 eV was applied within the GGA+U formalism in ThMnPN to reproduce the experimental Mn moment. We also found that, as the Mn moments decrease in ThMnXN (X = As, P), the energy gaps also decrease and finally disappear at Mn moment 2.7 μB for ThMnAsN and 2.8 μB for ThMnPN. Therefore, our results stipulate a possible metal–insulator transition in ThMnXN (X = As, P) induced by the Mn local moment.
      Citation: Magnetochemistry
      PubDate: 2022-12-31
      DOI: 10.3390/magnetochemistry9010016
      Issue No: Vol. 9, No. 1 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 162: The Halogen Effect on the Magnetic
           Behaviour of Dimethylformamide Solvates in [Fe(halide-salEen)2]BPh4

    • Authors: Rafaela T. Marques, Frederico F. Martins, Deniz F. Bekiş, Ana I. Vicente, Liliana P. Ferreira, Clara S. B. Gomes, Sónia Barroso, Varun Kumar, Yann Garcia, Nuno A. G. Bandeira, Maria José Calhorda, Paulo N. Martinho
      First page: 162
      Abstract: Complexes [Fe(X-salEen)2]BPh4·DMF, with X = Br (1), Cl (2), and F (3), were crystallised from N-ethylethylenediamine with the aim of understanding the role of a high boiling point N,N′-dimethylformamide solvate in the spin crossover phenomenon. The counter ion was chosen for only being able to participate in weak intermolecular interactions. The compounds were structurally characterised by single crystal X-ray diffraction. Complex 1 crystallised in the orthorhombic space group P212121, and complexes 2 and 3 in the monoclinic space group P21/n. Even at room temperature, low spin was the predominant form, although complex 2 exhibited the largest proportion of the high-spin species according to both the magnetisation measurements and the Mössbauer spectra. Density Functional Theory calculations were performed both on the periodic solids and on molecular models for complexes 1–3 and the iodide analogue 4. While all approaches reproduced the experimental structures very well, the energy balance between the high-spin and low-spin forms was harder to reproduce, though some calculations pointed to the easier spin crossover of complex 2, as observed. Periodic calculations with the functional PBE led to very similar ΔEHS-LS values for all complexes but showed a preference for the low-spin form. However, the single-point calculations with B3LYP* showed, for the model without solvate, that the Cl complex should undergo spin crossover more easily. The molecular calculations also reflected this fact, which was more clearly defined when the cation–anion–solvate model was used. In the other models there was not much difference between the Cl, Br, and I complexes.
      Citation: Magnetochemistry
      PubDate: 2022-11-22
      DOI: 10.3390/magnetochemistry8120162
      Issue No: Vol. 8, No. 12 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 163: Effect of Metal-Oxide Phase on the
           Magnetic and Magnetocaloric Properties of La0.7Ca0.3MnO3-MO (MO=CuO, CoO,
           and NiO) Composite

    • Authors: Surendra Dhungana, Jacob Casey, Dipesh Neupane, Arjun K. Pathak, Sunil Karna, Sanjay R. Mishra
      First page: 163
      Abstract: The study reports the synthesis and characterization of the magnetic and magnetocaloric effects of metal-oxide (MO) modified La0.7Ca0.3MnO3 perovskites manganite. The powder composite samples, with a nominal composition of (1 − x)La0.7Ca0.3MnO3-xMO (Wt.% x = 0.0, 2.5, 5.0), were prepared using the facile autocombustion method, followed by an annealing process. The phase purity and structure were confirmed by X-ray diffraction. Temperature and field-dependent magnetization measurements and Arrott analysis revealed mixed first- and second-order phase transition (ferromagnetic to paramagnetic) in composite samples. The phase transition temperature shifted to lower temperatures with the addition of MO in the composite. A large magnetic entropy change (4.75 JKg−1K−1 at 1T and 8.77 JKg−1K−1 at 5T) was observed in the La0.7Ca0.3MnO3 (LCMO) sample and was suppressed, due to the presence of the MO phase in the composite samples. On the other hand, the addition of MO as a secondary phase in the LCMO samples enhanced their relative cooling power (RCP). The RCP of all composite samples increased with respect to the pristine LCMO, except for LCMO–5%NiO. The highest RCP value of 267 JKg−1 was observed in LCMO–5%CuO samples, which was 23.4% higher than the 213 JKg−1 observed for the pure LCMO at a magnetic field of 5T. The enhanced RCP of these composites makes them attractive for potential refrigeration applications.
      Citation: Magnetochemistry
      PubDate: 2022-11-22
      DOI: 10.3390/magnetochemistry8120163
      Issue No: Vol. 8, No. 12 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 164: The Effect of Co-Doping on the
           Structural and Magnetic Properties of Single-Domain Crystalline Copper
           Ferrite Nanoparticles

    • Authors: Gassem M. Alzoubi
      First page: 164
      Abstract: Nanoparticles of Co-doped copper ferrite, Cu0.75Co0.25Fe2O4, were successfully synthesized by hydrothermal method. The preparation conditions were optimized to produce small nanoparticles with crystallite size of 20 nm that fall into the single-domain regime. The influence of Co-doping on the structure and magnetic properties of pure copper ferrite, CuFe2O4, was investigated. The prepared ferrite nanoparticles were found to be in a single structural phase with a spinel-type structure, according to the XRD and FT-IR measurements. When compared to pure Cu ferrite, the addition of Co increased the lattice constant and decreased the density. The TEM results confirmed the spherical morphology of the prepared ferrite nanoparticles. For the entire temperature range of the ferrite nanoparticles, the magnetization measurements showed a single ferrimagnetic phase. It was observed that the coercivity and remanent magnetization increased with decreasing temperature. Magnetic anisotropy was found to increase with Co-doping in comparison to pure Cu ferrite. The ZFC–FC magnetization curves showed that the blocking temperature (TB) of the prepared nanoparticles is above room temperature, demonstrating that they are ferrimagnetic at room temperature and below. Additionally, it was found that decreasing the magnetic field lowers TB. The FC curves below TB were observed to be nearly flat, indicating spin-glass behavior that might be attributed to nanoparticle interactions and/or surface effects such as spin canting and spin disorder.
      Citation: Magnetochemistry
      PubDate: 2022-11-22
      DOI: 10.3390/magnetochemistry8120164
      Issue No: Vol. 8, No. 12 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 165: Coercivity and Exchange Bias in
           Ti-Doped Maghemite Nanoparticles

    • Authors: Venkatesha Narayanaswamy, Imaddin A. Al-Omari, Aleksandr S. Kamzin, Hafsa Khurshid, Abbas Khaleel, Bashar Issa, Ihab M. Obaidat
      First page: 165
      Abstract: Ti-doped maghemite nanoparticles of average crystallite size 12.9 nm were synthesized using the sol–gel method. The XRD profile mainly showed the presence of maghemite phase with very small phases of TiO2 (rutile and anatase). Magnetization hysteresis loops of the nanoparticles were obtained between −4 T to +4 T at temperatures of 2, 10, 30, 50, 70, 100, 150, 200, and 300 K under field cooling (FC) of 1, 2, 3, and 4 T and zero-field cooling conditions (ZFC). The coercivity displayed nonmonotonic field dependence while it decreased sharply with temperature and vanished at 150 K at all fields. Horizontal hysteresis loop shifts were observed in the 2–150 K temperature range in both the ZFC and FC conditions. The exchange bias effect became negligible in both ZFC and FC states above 50 K. Magnetization vs. applied field measurements were conducted in both ZFC and FC cooled conditions at several temperatures in the range of 2–400 K, with spin freezing being observed below 50 K. The exchange bias effect obtained below 50 K is suggested to be attributed to the competing roles of the long-range dipolar and short-range exchange coupled interactions.
      Citation: Magnetochemistry
      PubDate: 2022-11-23
      DOI: 10.3390/magnetochemistry8120165
      Issue No: Vol. 8, No. 12 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 166: Chiral Dy(III) Fluorescent
           Single-Molecule Magnet Based on an Achiral Flexible Ligand

    • Authors: Min Zeng, Lin Miao, Xue-Ru Wu, Cai-Ming Liu, Hui-Zhong Kou
      First page: 166
      Abstract: A novel multi-channel barcode module was developed by using chiral co-crystals which contain field-induced SMM behavior and different emission bands. The chiral co-crystals [Zn(H2L)Dy(DBM)2]4(ClO4)4⋅9CH3OH⋅H2O (1a) and [Zn(H2L)Dy(DBM)2]4(ClO4)4⋅8CH3OH⋅0.5H2O (1b) (H4L = 2,2′-[1,2-ethanediylbis[(hydroxyethylimino)methylene]]bis[6-methoxy-4-methyl-phenol], HDBM = dibenzoylmethane) were obtained through one-pot reaction of ZnII and DyIII with the achiral ligands H4L and HDBM. X-ray single crystal diffraction and CD spectroscopy confirmed that they are enantiomers crystallized in P43 (1a) and P41 (1b), both consisting of two ∆-[Zn(H2L)Dy(DBM)2]+ cations, two Λ-[Zn(H2L)Dy(DBM)2]+ cations and four (ClO4)− anions. The presence of DyIII ions endow them with the property of field-induced slow magnetic relaxation. The relatively low energy barrier of 35.0(9) K for complex 1 may be due to the poor axiality of the ligand field caused by the long Dy-Ophenoxy bond lengths and the small Ophenoxy-Dy-Ophenoxy bond angles. Moreover, when the organic ligands H4L (λex = 350 nm) and DyIII (λex = 420 nm) are excited, different emission spectra are observed.
      Citation: Magnetochemistry
      PubDate: 2022-11-23
      DOI: 10.3390/magnetochemistry8120166
      Issue No: Vol. 8, No. 12 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 167: Mesostructure and Magnetic Properties
           of SiO2-Co Granular Film on Silicon Substrate

    • Authors: Natalia A. Grigoryeva, Victor Ukleev, Alexey A. Vorobiev, Alexander I. Stognij, Nikolay N. Novitskii, Leonid V. Lutsev, Sergey V. Grigoriev
      First page: 167
      Abstract: Granular films SiO2(Co) exhibit unusual magnetic and magnetotransport properties which are strongly dependent on the composition of the film and material of a substrate. For example, the injection magnetoresistance (IMR) coefficient reaches a giant (GIMR) value of 105% at room temperature in SiO2(Co) films on an n-GaAs substrate. However, the IMR effect is negligible in the case of a similar granular film deposited on the n-Si substrate. In this report, the structural and magnetic properties of granular film SiO2(Co) on Si substrate are studied with the aim to understand the cause of the difference in IMR coefficients for SiO2(Co) thin film deposited on n-GaAs and on n-Si substrates. Investigations were carried out using complementary methods of Polarized Neutron Reflectometry, Grazing Incidence Small-Angle X-ray Scattering, X-ray Reflectometry, Scanning Electron Microscope, and SQUID magnetometry. It is shown that the interface layer between the granular film and Si substrate exhibits metallic rather than magnetic properties and eliminates the GIMR effect. This interface layer is associated with the Si diffusion to Co nanoparticles and the formation of the metallic cobalt silicides.
      Citation: Magnetochemistry
      PubDate: 2022-11-24
      DOI: 10.3390/magnetochemistry8120167
      Issue No: Vol. 8, No. 12 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 168: Selection of Magneto-Optical Material
           for a Faraday Isolator Operating in High-Power Laser Radiation

    • Authors: Ilya Snetkov, Jiang Li
      First page: 168
      Abstract: Faraday isolators are the inherent components of complex laser systems. The isolation degree is essentially determined by the effects that occur in its magneto-optical element, so the choice of material from which it is made is very important. The principal approaches to choosing a magneto-optical material for Faraday isolators are addressed. Characteristic features of materials for Faraday devices operating in laser radiation with high average and high peak power are considered. Some trends in magneto-optical ceramics and the advantages and shortcomings of a number of ceramic samples are analyzed. Using the proposed approaches and recommendations will allow to create devices with unique characteristics for any wavelength range for different practical applications.
      Citation: Magnetochemistry
      PubDate: 2022-11-24
      DOI: 10.3390/magnetochemistry8120168
      Issue No: Vol. 8, No. 12 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 169: Size and Ion-Doping Effects on
           Magnetic, Optical, and Phonon Properties of CuAlO2 Nanoparticles

    • Authors: Iliana Naumova Apostolova, Angel Todorov Apostolov, Julia Mihailova Wesselinowa
      First page: 169
      Abstract: The magnetic, optical, and phonon properties of ion-doped CuAlO2 nanoparticles on the Cu or Al site are theoretically investigated. The room temperature ferromagnetism in CuAlO2 nanoparticles can be due to the surface, size, and doping effects. The magnetization increases with the decreasing nanoparticle size. The different radii of the transition metal ion and the host Cu ion lead to compressive strain, to the enhancment of the exchange interaction constants, and to increased magnetization Ms and Curie temperature TC. By substitution with Mn or Cr on the Al site, tensile strain, a decrease in Ms, and an increase in dopants are observed. The size and ion-doping influence on the band-gap energy is also discussed. The phonon energy ω decreases, whereas the phonon damping γ increases with increasing temperature and decreasing NP size. They show a kink around TC ∼ 400 K. The behavior of ω and γ for different ion dopings is observed.
      Citation: Magnetochemistry
      PubDate: 2022-11-25
      DOI: 10.3390/magnetochemistry8120169
      Issue No: Vol. 8, No. 12 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 170: Mechanical Detection of Magnetic
           Phase Transition in Suspended CrOCl Heterostructures

    • Authors: Xiaoxi Li, Xuanzhe Sha, Ning Yan, Tongyao Zhang
      First page: 170
      Abstract: With their outstanding mechanical and magnetic characteristics, two-dimensional magnetic materials have attracted wide attentions in the field of nanoelectromechanics and spintronics. By tuning the mechanical resonance with external knobs, such as strain, electric and magnetic control, nanoelectromechanical sensors with novel functionalities have been successfully demonstrated. Here, we investigate the mechanical properties of the suspended membranes with few-layered antiferromagnetic material CrOCl. The results show that the Young’s modulus of CrOCl resonators is ~137.29 GPa by using a static detection method. Below the transition temperature TN, the mechanical resonance is found to strongly depend on the magnetic fields with an enormous blueshift of ~3.1% in the magnetic-field-induced phase transition. In addition, we also found that the variation of strain of system ∆ϵ was about 1.5 × 10−3 during the transition. Our study shows the great potential of two-dimensional magnetic materials in future nanoelectronic applications.
      Citation: Magnetochemistry
      PubDate: 2022-11-25
      DOI: 10.3390/magnetochemistry8120170
      Issue No: Vol. 8, No. 12 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 171: Amorphous Carbon Films with Embedded
           Well-Dispersed Nanodiamonds: Plasmon-Enhanced Analysis and Possible
           Antimicrobial Applications

    • Authors: Oleg Streletskiy, Elena Perevedentseva, Ilya Zavidovskiy, Artashes Karmenyan, Vladimir Sychev, Vera Sadykova, Anastasia Kuvarina, Chia-Liang Cheng
      First page: 171
      Abstract: An amorphous carbon film with embedded detonation nanodiamond (DND) particles (a-C:ND) was produced by magnetron sputtering of nanodiamond powder. An Ag film was deposited on the carbon structure by radiofrequency magnetron sputtering. The silver film was irradiated with a 150 eV Ar+ to form plasmonic-active nanoparticles (NP) on the surface of the a-C:ND. The structure of the obtained a-C:ND and a-C:ND/Ag structures were studied by scanning and transmission electron microscopy, electron energy-loss spectroscopy, UV–Visible absorption spectroscopy, Raman spectroscopy, and fluorescence lifetime imaging at two-photon excitation. The analysis revealed 76% of sp3-carbon and a good dispersion of diamond nanoparticles in the a-C. Surface-enhanced Raman scattering (SERS) was applied to investigate the a-C:ND/Ag structure, allowing for the observation of SERS from the sp2-carbon species and the absence of significant a-C:ND damage after Ar+ irradiation of the Ag overlayer. A plasmonic-metal-enhanced luminescence was observed at one- and two-photon excitations, revealing a two- to five-fold intensity increase. The activity of the used DNDs was tested using the agar diffusion method and observed against the bacteria of Bacillus subtilis, Staphylococcus aureus, and Escherichia coli and the fungi of Aspergillus niger, Aspergillus fumigatus, and the yeast of Candida albicans, showing DND activity against all the test strains of fungi.
      Citation: Magnetochemistry
      PubDate: 2022-11-26
      DOI: 10.3390/magnetochemistry8120171
      Issue No: Vol. 8, No. 12 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 172: Two-Dimensional Doped Materials

    • Authors: Junchi Liu, Bo Li, Qiuqiu Li
      First page: 172
      Abstract: The recently intensified research in atomically thick two-dimensional (2D) materials has been motivated by their unique properties and the possibility of updating the future electronic and optoelectronic technologies. Doping can change the band structure of a semiconductor and regulate its physical and chemical properties. Doping has a significant effect on the electronic structure of 2D materials due to their atomic thickness. Here, we present a tutorial review of 2D doped materials (except graphene), including various doping types and theoretical calculations, the preparation and characterization methods, and its multifunctional application. Finally, we will summarize by stating the current challenges and future opportunities in the development of 2D doped materials.
      Citation: Magnetochemistry
      PubDate: 2022-11-29
      DOI: 10.3390/magnetochemistry8120172
      Issue No: Vol. 8, No. 12 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 173: Magnetic Semiconductors as Materials
           for Spintronics

    • Authors: Andrei Telegin, Yurii Sukhorukov
      First page: 173
      Abstract: From the various aspects of spintronics the review highlights the area devoted to the creation of new functional materials based on magnetic semiconductors and demonstrates both the main physical phenomena involved and the technical possibilities of creating various devices: maser, p-n diode with colossal magnetoresistance, spin valve, magnetic lens, optical modulators, spin wave amplifier, etc. Particular attention is paid to promising research directions such as ultrafast spin transport and THz spectroscopy of magnetic semiconductors. Special care has been taken to include a brief theoretical background and experimental results for the new spintronics approach employing magnetostrictive semiconductors—strain-magnetooptics. Finally, it presents top-down approaches for magnetic semiconductors. The mechano-physical methods of obtaining and features of the physical properties of high-density nanoceramics based on complex magnetic oxides are considered. The potential possibility of using these nanoceramics as an absorber of solar energy, as well as in modulators of electromagnetic radiation, is shown.
      Citation: Magnetochemistry
      PubDate: 2022-11-29
      DOI: 10.3390/magnetochemistry8120173
      Issue No: Vol. 8, No. 12 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 174: Green Synthesis of Unsaturated Fatty
           Acid Mediated Magnetite Nanoparticles and Their Structural and Magnetic
           Studies

    • Authors: Amlan Kumar Das, Apoorva Fanan, Daoud Ali, Vijendra Singh Solanki, Brijesh Pare, Bader O. Almutairi, Neha Agrawal, Neera Yadav, Vikram Pareek, Virendra Kumar Yadav
      First page: 174
      Abstract: The green, cost-effective and sustainable synthesis of nanomaterials has been a key concern of scientists and researchers. In this view, MNPs were prepared using a sapota plant leaf extract and the surface of the magnetite nanoparticles was engineered with unsaturated fatty acids. The first report on the effect of unsaturation on the size and magnetic properties of magnetite nanoparticles (MNPs), prepared by the co-precipitation method, has been studied by coating surfactants on MNPs based on their unsaturation from zero to three (lauric acid, oleic acid, linoleic acid, linolenic acid). The size effect and magnetic properties of MNPs coated with a surfactant have been studied in comparison with uncoated magnetite nanoparticles. After the surface modification of the magnetite particle, it is necessary to check whether the magnetic property has been restored or not. Therefore, the magnetic property was studied. The presence of a surfactant on the surface of MNPs was confirmed by Fourier-transform infrared spectroscopy (FTIR), which was later confirmed by scanning electron microscope (SEM) and thermogravimetric analysis (TGA). The atomic structure was studied by X-ray diffraction (XRD) and the size of uncoated and surfactant-coated MNPs was determined by transmission electron microscopy (TEM) and the Scherrer equation by following XRD data. The magnetization property was analyzed by a vibrating sample magnetometer (VSM) at 10, 100 and 300 K and both bared and surfactant-coated MNPs exhibited a superparamagnetic nature at room temperature. The saturation magnetization (Ms) study shows that MNPs coated with a surfactant have a lower saturation magnetization value in comparison to uncoated NPs, confirming surface layering. Because the magnetic fluid has been stabilized in the aqueous medium, the double-layer model is expected to prevail.
      Citation: Magnetochemistry
      PubDate: 2022-11-30
      DOI: 10.3390/magnetochemistry8120174
      Issue No: Vol. 8, No. 12 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 175: Effect of ZrO2 Content on
           Microstructure Evolution and Sintering Properties of (Tb0.7Lu0.3)2O3
           Magneto-Optic Transparent Ceramics

    • Authors: Yu Xin, Tao Xu, Yaozhi Wang, Peng Luo, Weiwei Li, Bin Kang, Bingchu Mei, Wei Jing
      First page: 175
      Abstract: In this paper, (Tb0.7Lu0.3)2O3 magneto-optical transparent ceramics with different ZrO2 doping levels (0~5 at%) were prepared by hydrogen sintering and sequential HIP technique using ZrO2 as a sintering aid. The effect of ZrO2 doping content on the microstructure and optical properties of (Tb0.7Lu0.3)2O3 ceramics was analyzed. We found that the optimal doping content of ZrO2 was 3 at%. The transmittance of 3 at% ZrO2-doped (Tb0.7Lu0.3)2O3 ceramics at the wavelength of 1064 nm was 74.84 %, and the Verdet constant was approximately 275.28 rad·T−1·m−1 at the wavelength of 650 nm.
      Citation: Magnetochemistry
      PubDate: 2022-12-01
      DOI: 10.3390/magnetochemistry8120175
      Issue No: Vol. 8, No. 12 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 176: Effect of the Preparation Conditions
           on the Magnetic Coercivity of CoPt Alloy Nanowires

    • Authors: Mihai Tibu, Nicoleta Lupu, Oana-Georgiana Dragos-Pinzaru
      First page: 176
      Abstract: In this paper, 3 µm length and 200 nm diameter CoPt nanowire arrays (NWs) with different Co contents were prepared by electrodeposition at a controlled potential from an aqueous hexachloroplatinate solution. The synthesis occurred at two different solution pH values (2.5 and 5.5) in an electrochemical bath free of additives, as well as with saccharin as an organic additive. A complete morphological, compositional, structural and magnetic characterization of the as-prepared nanowires has been carried out. The results show that, by controlling the electrodeposition conditions, the Co content of the alloy can be tuned from 16% to 92%. The crystalline structure of the as-deposited compounds can also be controlled, with the obtained data showing that the face-centered cubic (fcc) crystalline structure changes into a hexagonal close-packed (hcp) structure when saccharin is used as an organic additive during the electrodeposition. The changes in the alloy’s composition and crystalline structure strongly influence the magnetic properties of the NW’s arrays.
      Citation: Magnetochemistry
      PubDate: 2022-12-01
      DOI: 10.3390/magnetochemistry8120176
      Issue No: Vol. 8, No. 12 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 177: Biodiesel Production from Macroalgae
           Oil from Fucus vesiculosus Using Magnetic Catalyst in Unconventional
           Reactor Assisted by Magnetic Field

    • Authors: Euripedes Garcia Silveira Junior, Lilian Fiori Boechat de Souza, Victor Haber Perez, Oselys Rodriguez Justo, Euclésio Simionatto, Lincoln Carlos Silva de Oliveira
      First page: 177
      Abstract: A novel magnetic catalyst with hollow cylinder shape based on K2CO3/γ-Al2O3/Sepiolite/CoFe2O4 was prepared to convert macroalgae oil (Fucus vesiculosus) into biodiesel in an unconventional reactor assisted by magnetic field. Catalysts were formulated by the extrusion and characterized satisfactorily by physicochemical (mechanical strength, XRD, TG/DTG, FTIR and TPD-CO2), magnetic (VSM and EPR), morphological (SEM) and textural properties (BET). While their catalytic performance was also evaluated at 70 °C, oil: ethanol molar ratio 1:12 and 6 wt.% of catalyst using two different reaction systems for comparative purposes: (a) conventional stirred reactor and (b) fluidized bed reactor assisted by a magnetic field. The attained biodiesel presents properties in accordance with the standard limits (ASTM and EN) and total conversion (>99%) was observed in both cases after 2 h of reaction without significant differences between the two reactors. However, the magnetic properties of these catalysts allowed stabilization of the bed under a magnetic field and easy magnetic catalyst separation/recovery at the reaction end, showing their great potential for biodiesel production with regard to conventional process and thus, transforming it into a more sustainable technology.
      Citation: Magnetochemistry
      PubDate: 2022-12-01
      DOI: 10.3390/magnetochemistry8120177
      Issue No: Vol. 8, No. 12 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 178: Magnetic Field Assisted Spark
           Discharge-Generated Gold Nanostructures: XPS Study of Nitrogen Gas Fate
           and Chemical Composition of Gold Thin Films

    • Authors: Stefan Ručman, Winai Thongpan, Wattikon Sroila, Niwat Jhuntama, Pisith Singjai
      First page: 178
      Abstract: The sparking discharge process utilises high voltage to melt and evaporate tips of electrodes to create particles that can be deposited on substrate. In our research, we examine the influence of a magnetic field and nitrogen flow on gold thin-film formation onto quartz substrate. A positive effect of nitrogen flow and a 0.3 T external magnetic field was observed, in enhancement of surface plasmon band in UV visible and dispersal of nanoparticles without agglomeration. We also detected and described nitrification occurrences of gold measured by XPS at 407 eV and nitridification of quartz substrate on which gold particles are collected. These nitrogen-based chemical reactions occurred during sparking of gold wire inside of ambient air and in the magnetic field, as well during pure nitrogen flow. We measured the valence band electronic structure of gold nanoparticles deposited onto quartz substrate and found that gold thin film prepared in the magnetic field under nitrogen flow has the lowest value of 1.5 eV. Preparation of gold thin films in the magnetic field under nitrogen flow offers a highly dispersed and convenient method for productions of thin films.
      Citation: Magnetochemistry
      PubDate: 2022-12-01
      DOI: 10.3390/magnetochemistry8120178
      Issue No: Vol. 8, No. 12 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 179: Microstructure, Critical Behavior and
           Magnetocaloric Properties of Melt-Spun Ni51.82Mn32.37In15.81

    • Authors: Karima Dadda, Safia Alleg, Saida Souilah, Jason Daza, Joan Saurina, Joan-Josep Suñol, Lotfi Bessais, El-Kebir Hlil
      First page: 179
      Abstract: Heusler alloy with an atomic composition of Ni51.82Mn32.37In15.81 was prepared by melt spinning from arc-melted ingots. X−ray diffraction, scanning electron microscopy and magnetic measurements were used to study the structural, microstructural and magnetic properties. The crystal structure consists of a mixture of B2 austenite (~50%) and 14M martensite (~50%). The alloy undergoes a second order magnetic transition at a Curie temperature of TcA=194.2 K. The hysteresis loop reveals the occurrence of exchange bias phenomenon at room temperature. The critical exponents β, γ and δ were estimated using modified Arrott plots, Kouvel–Fisher curves and critical isothermal analysis. The respective values are β=0.500±0.015, γ=1.282±0.055 and δ=3.003±0.002. The critical behaviour in ribbons is governed by the mean field model with a dominated long-range order of ferromagnetic interactions. The maximum entropy change, ∆SMmax, for an applied magnetic field of 5 T reaches an absolute value of 0.92 J/kg.K. The experimental results of entropy changes are in good agreement with those calculated using Landau theory.
      Citation: Magnetochemistry
      PubDate: 2022-12-02
      DOI: 10.3390/magnetochemistry8120179
      Issue No: Vol. 8, No. 12 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 180: Magnetic Domain Structure of
           Lu2.1Bi0.9Fe5O12 Epitaxial Films Studied by Magnetic Force Microscopy and
           Optical Second Harmonic Generation

    • Authors: Marina Temiryazeva, Evgeny Mamonov, Anton Maydykovskiy, Alexei Temiryazev, Tatiana Murzina
      First page: 180
      Abstract: Magnetic structure of functional magnetic dielectrics is traditionally of high interest. Here, we use the magnetic force microscopy (MFM) and nonlinear-optical probe of second harmonic generation for studies of surface domain structure of monocrystalline Lu2.1Bi0.9Fe5O12 garnet films. The transformation of the magnetic domains under the application of the dc magnetic field is revealed by the MFM for both the top-view and the cleavage of the iron-garnet layer. Complementary magnetic force and second harmonic generation microscopy show that the considered film reveals the magnetization inclined with respect to the film’s normal, with its orientation being inhomogeneous within the film’s thickness. The second harmonic generation (SHG) microscopy confirms the zigzag structure of the surface-closing domain with the magnetization containing in-plane and out-of-plane magnetization components. We believe that these features of magnetic behavior of garnet films are important for the design of garnet-based magnetic devices.
      Citation: Magnetochemistry
      PubDate: 2022-12-04
      DOI: 10.3390/magnetochemistry8120180
      Issue No: Vol. 8, No. 12 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 181: Structural Parameters of the
           Interaction between Ciprofloxacin and Human Topoisomerase-II β
           Enzyme: Toward New 19F NMR Chemical Shift Probes

    • Authors: Thais Aparecida Sales, Mateus Aquino Gonçalves, Teodorico Castro Ramalho
      First page: 181
      Abstract: New tools for cancer diagnosis are being studied since early diagnosis can be crucial for a successful treatment. In this context, the use of NMR probes constitutes an efficient method of diagnosis. In this study, we investigated the use of ciprofloxacin to indirectly label the overexpression of topoisomerase-II enzymes by changes in 19F NMR chemical shifts of ciprofloxacin. Increased topoisomerase-II expression has been associated with cancer occurrence, mainly with aggressive forms of breast cancer, thus constituting a promising molecular target for new tumor cell identifiers. Using DFT calculations, we performed a spectroscopy analysis of ciprofloxacin in different chemical environments and evaluated the solvent and enzymatic effects. Our results show that ciprofloxacin forms a stable complex with the enzyme, and the main intermolecular interactions between ciprofloxacin and human topoisomerase-IIβ are hydrogen bonds, followed by π-π stacking and electrostatic interactions. Additionally, a shift of 6.04 ppm occurs in the 19F NMR signal when ciprofloxacin interacts with the human topoisomerase-IIβ enzyme, and this parameter may be an indirect marker indicating the overexpression of these enzymes in the body.
      Citation: Magnetochemistry
      PubDate: 2022-12-07
      DOI: 10.3390/magnetochemistry8120181
      Issue No: Vol. 8, No. 12 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 182: Experimental and Numerical Analyses
           of a Novel Magnetostatic Force Sensor for Defect Inspection in
           Ferromagnetic Materials

    • Authors: Bo Wang, San Zhang, Xinyue Chen, Fujie Wang, Baohui Xu
      First page: 182
      Abstract: An innovative magnetostatic force sensor consisting of a laser source, a tiny cantilever beam, and a small permanent magnet was developed and used for defect inspection in ferromagnetic samples in the present article. The penetrating zone within a ferromagnetic material under the magnetic field provided by a permanent magnet was called the magnetic sensing zone (MSZ), and surface or internal defects within the MSZ were inspected by measuring the change in the magnetostatic force. This magnetostatic force could be calculated by the Maxwell tensor integrating over the surface and interface of a ferromagnetic material. Numerical and experimental results demonstrated that this sensor was reliable and could precisely inspect the defects of different sizes in ferromagnetic samples. In summary, the sensor proposed in this paper has the potential for industrial applications to detect surface and sub-surface tiny defects on ferromagnetic steel thin sheets, such as the zinc slag defect of hot galvanized sheets, cracks on cold-rolled sheets, and the ferromagnetic oscillation marks of continuous casting.
      Citation: Magnetochemistry
      PubDate: 2022-12-07
      DOI: 10.3390/magnetochemistry8120182
      Issue No: Vol. 8, No. 12 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 183: A Sustainable Amine Magnetic
           Biocomposite Based on Rice Husk–Sugarcane Bagasse Fiber for Lead and
           Contaminant Adsorption in Aqueous Solution

    • Authors: Iryanti Fatyasari Nata, Chairul Irawan, Meilana Dharma Putra, Hesti Wijayanti, Yuniza Shentya Dewi, Yenny Meliana
      First page: 183
      Abstract: Biomass is a material that can be potentially used as a natural fiber resource. Rice husk (RH) and sugarcane bagasse (SB), respectively containing 36.6% and 60% cellulose, are fibers that have the potential for biocomposite formation. In this study, an amine magnetic biocomposite (B-MNH2) was prepared by a one-step solvothermal reaction. Delignified RH and SB fibers at a ratio of 1:1 were added to a mixture of ethylene glycol, iron chloride, and 1,6-hexanediamine, and kept in a stainless steel autoclave reactor at 200 °C for 6 h. The obtained B-MNH2 contained 64.5% of Fe and 2.63 mmol/g of amine. Its surface area increased significantly from 9.11 m2/g to 25.81 m2/g after amine functionalization, and its optimum adsorption for Pb(II) ions was achieved within 360 min at 596.82 mg/g and pH 5. Moreover, the pseudo-first-order mechanism fitted well to the adsorption model. Other parameters, such as chemical oxygen demand (COD), total suspended solid (TSS), and dye during adsorption were also reduced by about 67.7%, 95.6%, and 89%, respectively. B-MNH2 showed a slight decrease in performance by only 8% after the fourth repeated use. The amine magnetic biocomposite led to the development of a potential adsorbent due to the high surface area, stable material, and easy separation, and was capable of absorbing contaminants from an aqueous solution.
      Citation: Magnetochemistry
      PubDate: 2022-12-09
      DOI: 10.3390/magnetochemistry8120183
      Issue No: Vol. 8, No. 12 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 184: Magnetorheological Finishing of
           Chemically Treated Electroless Nickel Plating

    • Authors: Mayank Kumar, Tharra Bhavani, Sunil Rawal, Ajay Sidpara
      First page: 184
      Abstract: Electroless nickel plating with a nanofinished surface is used in space mirrors, automobile parts, aircraft components, optical instruments, and electronic equipment. Finishing of these components using conventional finishing techniques is limited due to size, shape, material, and process constraints. This work reports the nanofinishing of electroless nickel-plated surfaces using a magnetorheological finishing process where the surfaces are pre-treated with chemicals. The chemicals used in this work are hydrogen peroxide (H2O2) and hydrofluoric acid (HF). The effect of exposure time and concentration on the microhardness and roughness is studied to understand the surface chemistry after chemical treatment. The hydrogen peroxide forms a passivated layer, and it helps in easy material removal. Hydrofluoric acid improves surface quality and also helps in the removal of contaminants. The finished surface is characterized to understand the effect of chemical treatment on the finishing rate and surface topography. Normal and tangential forces are mainly affected by the hardness and surface condition after the chemical treatment. The best combination of parameters (chemical treatment with 1% HF for 30 min) was obtained and finishing was carried out to obtain a nanofinished surface with its areal surface roughness (Sa) reduced to 10 nm.
      Citation: Magnetochemistry
      PubDate: 2022-12-11
      DOI: 10.3390/magnetochemistry8120184
      Issue No: Vol. 8, No. 12 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 185: Bifunctional Magnetite–Gold
           Nanoparticles for Magneto-Mechanical Actuation and Cancer Cell Destruction
           

    • Authors: Anastasiia S. Garanina, Maria V. Efremova, Alexey E. Machulkin, Evgeny V. Lyubin, Natalia S. Vorobyeva, Oxana A. Zhironkina, Olga S. Strelkova, Igor I. Kireev, Irina B. Alieva, Rustem E. Uzbekov, Viatcheslav N. Agafonov, Igor V. Shchetinin, Andrey A. Fedyanin, Alexander S. Erofeev, Peter V. Gorelkin, Yuri E. Korchev, Alexander G. Savchenko, Maxim A. Abakumov
      First page: 185
      Abstract: Magnetite–gold dumbbell nanoparticles are essential for biomedical applications due to the presence of two surfaces with different chemical natures and the potential combination of magnetic and plasmonic properties. Here, the remote actuation of Fe3O4-Au hybrid particles in a rotating (1 Hz, 7 mT), static (7 mT) or pulsed low-frequency (31 Hz, 175 mT, 30 s pulse/30 s pause) magnetic field was studied. The particles were synthesized by a high-temperature wet chemistry protocol and exhibited superparamagnetic properties with the saturation magnetization of 67.9 ± 3.0 Am2 kg−1. We showcased the nanoparticles’ controlled aggregation in chains (rotating/static magnetic field) in an aqueous solution and their disaggregation when the field was removed. The investigation of nanoparticle uptake by LNCaP and PC-3 cancer cells demonstrated that Fe3O4-Au hybrids mainly escaped endosomes and accumulated in the cytoplasm. A significant fraction of them still responded to a rotating magnetic field, forming short chains. The particles were not toxic to cells at concentrations up to 210 μg (Fe3O4) mL−1. However, cell viability decrease after incubation with the nanoparticles (≥70 μg mL−1) and exposure to a pulsed low-frequency magnetic field was found. We ascribe this effect to mechanically induced cell destruction. Overall, this makes Fe3O4-Au nanostructures promising candidates for intracellular actuation for future magneto-mechanical cancer therapies.
      Citation: Magnetochemistry
      PubDate: 2022-12-12
      DOI: 10.3390/magnetochemistry8120185
      Issue No: Vol. 8, No. 12 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 186: Synthesis and Characterization of
           Composites with Y-Hexaferrites for Electromagnetic Interference Shielding
           Applications

    • Authors: Sajjad Ahmad Khan, Irshad Ali, Abid Hussain, Hafiz Muhammad Asif Javed, Vitalii A. Turchenko, Alex V. Trukhanov, Sergei V. Trukhanov
      First page: 186
      Abstract: The current research is focused on the chemical process and characterization of Co-based Y-type hexaferrite, electrochemically active polypyrrole doped with dodecylbenzene sulphonicacid (PPy-DBSA) and their composites. The microemulsion technique was used to produce hexaferrite with the formula Sr2Co2Fe12O22. The resistivity of pure ferrite specimens was 103 ohm-cm, which was lower than the 106 ohm-cm resistivity of the monomer utilized in the polymerization operation. As the temperature increases, the DC resistance decreases, revealing the specimens’ semiconductor nature. The cole-cole plots have been used to assess whether significant grain boundaries were involved in the dielectric relaxation process. By increasing the frequency, the electrochemical performance of all specimens was enhanced. Using the rate equation, ionic conductivity demonstrates that polarons are responsible for conduction. Because of the characteristics of the polymer PPY-conducting DBSA, the composites PPY/DBSA + Sr2Co2Fe12O22 exhibit a higher dielectric loss of 35 at 1 MHz. This specimen is perfect for electrical radiation shielding (EMI).These ferrites are widely used as permanent magnets, in microwave devices, high-density perpendicular media, and rigid disk media without lubricant and protective layers.
      Citation: Magnetochemistry
      PubDate: 2022-12-12
      DOI: 10.3390/magnetochemistry8120186
      Issue No: Vol. 8, No. 12 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 187: Wavelet-Based Three-Dimensional
           Inversion for Geomagnetic Depth Sounding

    • Authors: Shiwen Li, Yunhe Liu
      First page: 187
      Abstract: The complexity of Earth’s structure poses a challenge to the multiscale detection capability of geophysics. In this paper, we present a new wavelet-based three-dimensional inversion method for geomagnetic depth sounding. This method is based on wavelet functions to transfer model parameters in the space domain into the wavelet domain. The model is represented by wavelet coefficients containing both large- and fine-scale information, enabling wavelet-based inversion to describe multiscale anomalies. L1-norm measurement is applied to measure the model roughness to accomplish the sparsity constraint in the wavelet domain. Meanwhile, a staggered-grid finite difference method in a spherical coordinate system is used to calculate the forward responses, and the limited-memory quasi-Newton method is applied to seek the solution of the inversion objective function. Inversion tests of synthetic data for multiscale models show that wavelet-based inversion is stable and has multiresolution. Although higher-order wavelets can lead to finer results, our tests present that a db6 wavelet is suitable for geomagnetic depth sounding inversion. The db6 inversion results of responses at 129 geomagnetic observatories around the world reveal a higher-resolution image of the mantle.
      Citation: Magnetochemistry
      PubDate: 2022-12-12
      DOI: 10.3390/magnetochemistry8120187
      Issue No: Vol. 8, No. 12 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 188: Stability Analysis of Buoyancy
           Magneto Flow of Hybrid Nanofluid through a Stretchable/Shrinkable Vertical
           

    • Authors: Umair Khan, Aurang Zaib, Anuar Ishak, Abeer M. Alotaibi, Sayed M. Eldin, Nevzat Akkurt, Iskandar Waini, Javali Kotresh Madhukesh
      First page: 188
      Abstract: The utilization of hybrid nanofluids (HNs) to boost heat transfer is a promising area of study, and thus, numerous scientists, researchers, and academics have voiced their admiration and interest in this area. One of the main functions of nanofluids is their dynamic role in cooling small electrical devices such as microchips and associated gadgets. The major goal of this study is to perform an analysis of the buoyancy flow of a shrinking/stretching sheet, whilst considering the fascinating and practical uses of hybrid nanofluids. The influence of a nonlinear heat source/sink induced by a micropolar fluid is also inspected. Water-based alumina and copper nanoparticles are utilized to calculate the fine points of the fluid flow and the features of heat transfer. The governing equations are framed with acceptable assumptions and the required similarity transformations are used to turn the set of partial differential equations into ordinary differential equations. The bvp4c technique is used to solve the simplified equations. Dual solutions are presented for certain values of stretching/shrinking parameters as well as the mixed convective parameter. In addition, the shear stress coefficient in the first-branch solution (FBS) escalates and decelerates for the second-branch solution (SBS) with the superior impact of the magnetic parameter, the mass transpiration parameter, and the solid nanoparticles volume fraction, while the contrary behavior is seen in both (FB and SB) solutions for the larger values of the material parameter.
      Citation: Magnetochemistry
      PubDate: 2022-12-14
      DOI: 10.3390/magnetochemistry8120188
      Issue No: Vol. 8, No. 12 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 189: Application of the
           Heptacyanidorhenate(IV) as a Metalloligand in the Design of Molecular
           Magnets

    • Authors: Vostrikova
      First page: 189
      Abstract: This review is devoted to an analysis of currently known heterometallic molecular magnets based on an orbitally degenerate 5d metalloligand, [ReIV(CN)7]3–. Heptacyanidometallates with a pentagonal bipyramidal structure of the coordination site and degenerate ground spin state are the source of anisotropic magnetic exchange interactions upon the formation of cyanide-bonded assemblies involving the paramagnetic complexes of the first transition series. Therefore, the development of methods for chemical design using such molecular magnetic modules is extremely important. If for the 4d congener, isoelectronic [MoIII(CN)7]3–, a family of approximately 40 heterometallic compounds, was obtained, whereas for heptacyanorhenate(IV), no more than 20 are known. However, as a result of recent studies, heterobimetallic magnetic assemblies of all dimensionalities have been synthesized, from 0D to 1D, demonstrating slow magnetization relaxation, to 2D networks and 3D frameworks possessing large magnetic hysteresis. The most anisotropic is a 2D network, PPN[{MnIII(acacen)}2ReIV(CN)7]·Solv, with a critical temperature of 20 K and magnetic hysteresis with a record coercivity for cyanide-bridged molecular materials.
      Citation: Magnetochemistry
      PubDate: 2022-12-14
      DOI: 10.3390/magnetochemistry8120189
      Issue No: Vol. 8, No. 12 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 190: MHD Nanofluid Convection and Phase
           Change Dynamics in a Multi-Port Vented Cavity Equipped with a Sinusoidal
           PCM-Packed Bed System

    • Authors: Fatih Selimefendigil, Hakan F. Öztop
      First page: 190
      Abstract: In this study, impacts of using a sinusoidal shape encapsulated phase change material (PCM) packed bed (PB) system on the phase change and thermal performance are analyzed in multi-port vented cavity under a partially active magnetic field during hybrid nanoliquid convection. The current study is performed for different magnetic field strengths of domains (Hartmann number between 0 and 50), wave number (between 1 and 8), wave amplitude (between 0.01 H and 0.15 H), and nanoparticle loading (between 0 and 2%) by using the finite element method. The sinusoidal shape of the PCM-PB zone and varying its geometrical form are both found to affect the phase change process and thermal performance. When wave amplitude (Hp) rises from 0.01 H to 0.15 H, full phase change time (t-fr) increases by about 33% while average Nu increases by about 55%. When a partially active magnetic field is imposed at the highest value, up to 30.3% reduction in t-fr is obtained, while average Nu rises by about 9% at t = 18 min. The value of t-fr is reduced by about 15% while spatial average Nu rises by about 55% at the highest nanoparticle loading.
      Citation: Magnetochemistry
      PubDate: 2022-12-16
      DOI: 10.3390/magnetochemistry8120190
      Issue No: Vol. 8, No. 12 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 137: Synthesis of a Doped
           α-Fe2O3/g-C3N4 Catalyst for High-Efficiency Degradation of Diazinon
           Contaminant from Liquid Wastes

    • Authors: Tariq J. Al-Musawi, Rasoul Asgariyan, Murat Yilmaz, Nezamaddin Mengelizadeh, Abolfazl Asghari, Davoud Balarak, Mohammad Darvishmotevall
      First page: 137
      Abstract: In this work, a hematite/porous graphite carbon-nitride (α-Fe2O3/g-C3N4) catalyst was synthesized through the doping of hematite loaded onto porous graphite carbon-nitride using a heat treatment process. Then, the ability of catalyst was evaluated to degrade diazinon (DZN) for the first time, mainly via the sonophotocatalytic process. Among the samples, the greatest DZN degradation was observed in the sonophotocatalytic system, which separated 100% of DZN from the aqueous solution after 50 min, while the removal percentages for the sonocatalytic, photocatalytic, and adsorption systems were 72.9, 89.1, and 58.1%, respectively. The results of scavengers showed that both sulfate and hydroxyl radicals (•OH) participated in removing DZN, although positive holes and negative •OH played a major role. Moreover, the removal efficiencies of the target pollutant using the sonophotocatalytic process were higher than those using the photocatalytic, sonocatalytic, and adsorption processes. The reaction profile followed pseudo-first-order kinetics, and the reaction rate coefficient for the sonophotocatalytic system was 2.2 times higher than that of the photocatalytic system and 2.64 times higher than that of the sonocatalytic system. The energy consumption of the sonophotocatalytic system after 60 min was 11.6 kWh/m3, while it was 31.1 kWh/m3 for the photocatalytic system. A DZN removal percentage of 100% was obtained after 50 min under the following conditions: UV intensity of 36 watts, ultrasound frequency of 36 kHz, DZN concentration of 50 mg/L at pH 5, and α-Fe2O3/g-C3N4 dosage of 0.4 g/L. The catalyst reusability was examined with only a 9.9% reduction in efficiency after eight consecutive cycles. The chemical oxygen demand (COD) and total organic compound (TOC) removal percentages were 95.6% and 88.6%, respectively, and the five-day biochemical oxygen demand (BOD5)/COD ratio was 0.16 at the beginning of the degradation process and 0.69 at the end of the process. In addition, toxicological experiments showed that degradation of DZN by the sonophotocatalytic process exhibited low toxicity. All results confirmed that the sonophotocatalytic process using α-Fe2O3/g-C3N4 was a highly efficient process for DZN pollutant removal from liquid wastes.
      Citation: Magnetochemistry
      PubDate: 2022-10-22
      DOI: 10.3390/magnetochemistry8110137
      Issue No: Vol. 8, No. 11 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 138: Ball Milled Gd Flakes Subjected to
           Heat Treatments: Structure, Magnetic and Magnetocaloric Properties

    • Authors: Andrey V. Svalov, Dmitriy S. Neznakhin, Andrey V. Arkhipov, Sergey V. Andreev, Nadezhda V. Selezneva, Aitor Larrañaga, Galina V. Kurlyandskaya
      First page: 138
      Abstract: Gd flake samples were prepared by conventional ball milling technique starting from rapidly quenched Gd ribbons and followed by vacuum annealing in different conditions. Heat treatments were conducted in a vacuum at selected temperatures up to 600 K. The structural features, magnetic and magnetocaloric properties were comparatively analyzed. The change in magnetic entropy was calculated using an experimental set of magnetic isotherms measured in a wide range of temperatures. The variations in the refrigeration capacity and the exponent of the magnetic entropy change in the external magnetic field were carefully calculated and analyzed.
      Citation: Magnetochemistry
      PubDate: 2022-10-23
      DOI: 10.3390/magnetochemistry8110138
      Issue No: Vol. 8, No. 11 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 139: Fungus-Based Magnetic
           Nanobiocomposites for Environmental Remediation

    • Authors: Thais de Oliveira Chaves, Raquel Dosciatti Bini, Verci Alves de Oliveira Junior, Andressa Domingos Polli, Adriana Garcia, Gustavo Sanguino Dias, Ivair Aparecido dos Santos, Paula Nunes de Oliveira, João Alencar Pamphile, Luiz Fernando Cotica
      First page: 139
      Abstract: The use of a variety of microorganisms for the degradation of chemicals is a green solution to the problem of environmental pollution. In this work, fungi–magnetic nanoparticles were studied as systems with the potential to be applied in environmental remediation and pest control in agriculture. High food demand puts significant pressure on increasing the use of herbicides, insecticides, fungicides, pesticides, and fertilizers. The global problem of water pollution also demands new remediation solutions. As a sustainable alternative to commercial chemical products, nanobiocomposites were obtained from the interaction between the fungus M. anisopliae and two different types of magnetic nanoparticles. Fourier transform infrared spectroscopy, optical and electron microscopy, and energy dispersive spectroscopy were used to study the interaction between the fungus and nanoparticles, and the morphology of individual components and the final nanobiocomposites. Analyses show that the nanobiocomposites kept the same morphology as that of the fungus in natura. Magnetic measurements attest the magnetic properties of the nanobiocomposites. In summary, these nanobiocomposites possess both fungal and nanoparticle properties, i.e., nanobiocomposites were obtained with magnetic properties that provide a low-cost approach benefiting the environment (nanobiocomposites are retrievable) with more efficiency than that of the application of the fungus in natura.
      Citation: Magnetochemistry
      PubDate: 2022-10-26
      DOI: 10.3390/magnetochemistry8110139
      Issue No: Vol. 8, No. 11 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 140: Applications of Magneto
           Electrochemistry and Magnetohydrodynamics in Microfluidics

    • Authors: Haim H. Bau
      First page: 140
      Abstract: Magnetic fields affect electrolytes in diverse ways. This paper focuses on the interactions among electric, magnetic, and flow fields and the applications of the resulting phenomena in microfluidics. When an electrical current is transmitted in an electrolyte in the presence of an external magnetic field, a Lorentz body force results, which may induce pressure gradients and fluid motion—magnetohydrodynamics (MHD). The resulting advection is used to pump fluids, induce/suppress flow instabilities, and control mass transfer in diverse electrochemical processes. When an electrolyte flows in the presence of a magnetic field, electromotive force (emf) is induced in the electrolyte and can be used for flow metering, hydrogen production, and energy conversion. This review describes the governing equations for modeling MHD flows in electrolytes and MHD phenomena and applications relevant to microfluidic systems, such as the use of MHD to pump and stir fluids, propel swimmers, and control fluid flow in fluidic networks without any mechanical components. The paper also briefly assesses the impact of magnetic resonance imaging (MRI) on blood flow. MHD in electrolytes is a highly interdisciplinary, combining electrokinetics, fluid mechanics, electrochemistry, and Maxwell equations.
      Citation: Magnetochemistry
      PubDate: 2022-10-26
      DOI: 10.3390/magnetochemistry8110140
      Issue No: Vol. 8, No. 11 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 141: Bandwidth Enhancement of a Mobile
           Phone Antenna Using Ferrite Slab

    • Authors: Peng Li, Wei-Hua Zong, Zhejun Jin, Zhiqun Yang, Xiaoyun Qu, Shandong Li
      First page: 141
      Abstract: A novel technique to enhance the bandwidth of mobile phone antennas using YIG ferrite is proposed. The technique is applied in two slot antennas which are the proposed antenna and the reference antenna. The two antennas have the same shaped slot consisting of a rectangle connected to a circle etched on the ground plane. A ferrite slab is attached at the region near the circular slot on the ground plane of each antenna. The measured bandwidth of the proposed antenna with ferrite slab is enhanced to 0.669–1.533 and 1.69–5 GHz compared with the bandwidth of 0.81–1.44 and 2.3–5 GHz for the antenna without ferrite. The bandwidth of the reference antenna with ferrite slab is enhanced to 0.715–5 GHz compared with the bandwidth of 0.813–1.01, 1.11–1.3 and 2.33–5 GHz for the antenna without ferrite loading. The technique has the virtues of easy fabrication and low cost.
      Citation: Magnetochemistry
      PubDate: 2022-10-26
      DOI: 10.3390/magnetochemistry8110141
      Issue No: Vol. 8, No. 11 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 142: Layered Organic Conductors Based on
           BEDT-TTF and Ho, Dy, Tb Chlorides

    • Authors: Alexandra M. Flakina, Elena I. Zhilyaeva, Gennady V. Shilov, Maxim A. Faraonov, Svetlana A. Torunova, Dmitri V. Konarev
      First page: 142
      Abstract: Molecular semiconductors with lanthanide ions have been synthesized based on BEDT-TTF and lanthanide chlorides: (BEDT-TTF)2[HoCl2(H2O)6]Cl2(H2O)2 (1, which contains a 4f holmium cation), and (BEDT-TTF)2LnCl4(H2O)n (Ln = Dy, Tb, Ho (2–4), which contain 4f anions of lanthanides). Conductivity and EPR measurements have been carried out along with the SQUID magnetometry, and the crystal structure has been established for 1. The structure of 1 is characterized by an alternation of organic radical cation layers composed of BEDT-TTF chains and inorganic layers consisting of chains of the [HoCl2(H2O)6]+ cations interlinked by chlorine anions and crystallization water molecules. The magnetic susceptibility of 1–3 determined mainly by lanthanide ions follows the Curie–Weiss law with the Weiss temperatures of −3, −3, −2 K for 1–3, respectively, indicating weak antiferromagnetic coupling between paramagnetic lanthanide ions. The signals attributed to the BEDT-TTF+· radical cations only are observed in the EPR spectra of 1–3, which makes it possible to study their magnetic behavior. There are two types of chains in the organic layers of 1: the chains composed of neutral molecules and those formed by BEDT-TTF+· radical cations. As a result, uniform 1D antiferromagnetic coupling of spins is observed in the BEDT-TTF+· chains with estimated exchange interaction J = −10 K. The study of dynamic magnetic properties of 1–3 shows that these compounds are not SMMs.
      Citation: Magnetochemistry
      PubDate: 2022-10-28
      DOI: 10.3390/magnetochemistry8110142
      Issue No: Vol. 8, No. 11 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 143: Hydrophobic Magnetite Nanoparticles
           for Bioseparation: Green Synthesis, Functionalization, and
           Characterization

    • Authors: Vahid Alimohammadi, Seyyed Ali Seyyed Ebrahimi, Faezeh Kashanian, Zahra Lalegani, Mehran Habibi-Rezaei, Bejan Hamawandi
      First page: 143
      Abstract: In this study, three types of hydrophobized alkyl-modified magnetic nanoparticles (MNPs) comprising direct alkylated-MNPs (A-MNPs), silica-mediated alkyl MNPs (A-SiMNPs), and arginine (Arg)-mediated alkyl MNPs (A-RMNPs) were synthesized successfully. For this purpose, the co-precipitation method was used to synthesize, and octadecyl trimethoxy silane (OTMS) was used as a functionalizing agent. Accordingly, the hydrophobic octadecyl moieties were connected to MNPs. The nanoparticles (NPs) were characterized by XRD, SEM, FTIR, CHN, DLS, and zeta potential analyses. The synthesized coated MNPs represented a decrease in surface charge and magnetization alongside increased surface hydrophobicity and size. It was revealed that the alkylation process was successfully performed to all three MNPs, but A-SiMNPs showed the highest hydrophobicity. Additionally, the novel A-RMNPs, as the most biocompatible type, and A-MNPs showed the highest magnetization among the synthesized MNPs. The results indicate that synthesized NPs can play an important role in bio applications. However, it was revealed that alkyl chains are easily connected to all three MNPs, and that A-MNPs contained the highest alkyl chains and could affect the re-folding and denaturation process of recombinant proteins.
      Citation: Magnetochemistry
      PubDate: 2022-10-28
      DOI: 10.3390/magnetochemistry8110143
      Issue No: Vol. 8, No. 11 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 144: Oxygen Deficiency and
           Migration-Mediated Electric Polarization in Magnetic Fe,Co-Substituted
           SrTiO3−δ

    • Authors: Emilio A. Cortés Estay, Shyue P. Ong, Caroline A. Ross, Juan M. Florez
      First page: 144
      Abstract: We use density functional theory (DFT) calculations to show that oxygen vacancies (vO) and mobility induce noncentrosymmetric polar structures in SrTi1−x−yFexCoyO3−δ (STFC, x=y=0.125) with δ={0.125,0.25}, enhance the saturation magnetization, and give rise to large changes in the electric polarization ΔP . We present an intuitive set of rules to describe the properties of STFC, which are based on the interplay between (Co/Fe)-vO defects, magnetic cation coordination, and topological vacancy disorder. STFC structures consist of layered crystals with sheets of linearly organized O4,5,6-coordinated Fe–Co pairs, sandwiched with layers of O5-coordinated Ti. (Co/Fe)-vO defects are the source of crystal distortions, cation off-centering and bending of the oxygen octahedra which, considering the charge redistribution mediated by vO and the cations’ electronegativity and valence states, triggers an effective electric polarization. Oxygen migration for δ=0.125 leads to ΔP >∼10 µC/cm2 due to quantum-of-polarization differences between δ=0.125 structures. Increasing the oxygen deficiency to δ=0.25 yields ΔP , the O migration of which resolved polarization for δ=0.25 is >∼3 µC/cm2. Magnetism is dominated by the Fe,Co spin states for δ=0.125, and there is a contribution from Ti magnetic moments (∼1 μB) for δ=0.25. Magnetic and electric order parameters change for variations of δ or oxygen migration for a given oxygen deficiency. Our results capture characteristics observed in the end members of the series SrTi(Co,Fe)O3, and suggest the existence of a broader set of rules for oxygen-deficient multiferroic oxides.
      Citation: Magnetochemistry
      PubDate: 2022-11-01
      DOI: 10.3390/magnetochemistry8110144
      Issue No: Vol. 8, No. 11 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 145: Synthesis and Characterization of
           Bioactive Magnetic Nanoparticles from the Perspective of Hyperthermia
           Applications

    • Authors: Elena-Alina Moacă, Vlad Socoliuc, Dana Stoian, Claudia Watz, Daniela Flondor, Cornelia Păcurariu, Robert Ianoș, Cristiana Iulia Rus, Lucian Barbu-Tudoran, Alexandra Semenescu, Cristian Sarău, Adelina Chevereșan, Cristina Adriana Dehelean
      First page: 145
      Abstract: Magnetic iron oxide nanoparticles were obtained for the first time via the green chemistry approach, starting from two aqueous extracts of wormwood (Artemisia absinthium L.), both leaf and stems. In order to obtain magnetic nanoparticles suitable for medical purposes, more precisely with hyperthermia inducing features, a synthesis reaction was conducted, both at room temperature (25 °C) and at 80 °C, and with two formulations of the precipitation agent. Both the quality and stability of the synthesized magnetic iron oxide nanoparticles were physiochemically characterized: phase composition (X-ray powder diffraction (XRD)), thermal behavior (thermogravimetry (TG) and differential scanning calorimetry (DSC)), electron microscopy (scanning (SEM) and transmission (TEM)), and magnetic properties (DC and HF-AC). The magnetic investigation of the as-obtained magnetic iron oxide nanoparticles revealed that the synthesis at 80 °C using a mixture of NaOH and NH3(aq) increases their diameter and implicitly enhances their specific absorption rate (SAR), a mandatory parameter for practical applications in hyperthermia.
      Citation: Magnetochemistry
      PubDate: 2022-11-01
      DOI: 10.3390/magnetochemistry8110145
      Issue No: Vol. 8, No. 11 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 146: Magnetic Field-Induced Deformation of
           Isotropic Magnetorheological Elastomers

    • Authors: Diána Balogh, Sándor Guba, Barnabás Horváth, István Szalai
      First page: 146
      Abstract: In our research, the magnetic field-induced deformation of isotropic magnetorheological elastomer (MRE) discs loaded with two types of magnetite and an iron powder were examined. A measurement system using a microscope camera was assembled, and the magnitude of the deformation was determined from the optical contour obtained with digital image processing. We found that the MRE discs with a height-to-width aspect ratio of 1:2 underwent expansion in the direction of the external field in all cases. The magnitude of the dilatation increased with the magnetic field strength in cases of all filler materials, but the exact trend depended on the type and concentration of the filler. An inhibition of the polymerization of the matrix was observed in the case of one of the magnetite fillers, which resulted in a decreased zero-field elastic modulus at higher particle loadings. A correlation was found between the reduced elastic modulus and the increased magnitude of the deformation.
      Citation: Magnetochemistry
      PubDate: 2022-11-03
      DOI: 10.3390/magnetochemistry8110146
      Issue No: Vol. 8, No. 11 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 147: Design and Testing of a Disposable
           Flow Cuvette for Continuous Electroporation of a Bioreactor’s
           Initial Algae Cultivation

    • Authors: Georgios Banis, Maria Savvidou, Antonios Georgas, Athanasios Batagiannis, Fragiskos Kolisis, Angelo Ferraro, Evangelos Hristoforou
      First page: 147
      Abstract: Electroporation is a technique applied both in biomedical and biotechnological fields which uses a high-voltage electric current to temporarily destabilize the plasma membrane of living cells, permitting the introduction of small molecules as well as nucleic acids into the cytosol. Besides viral and chemical transfections, this method is a common way to manipulate living cells. However, the majority of electroporation machines available on the market can only work using batch-based cuvettes treating only a few micrograms of cells. To transform cells in the order of several grams in the quickest possible way, it is necessary to use a continuous-flow method. In this work, we present the design, electric and fluid dynamics simulations, construction and testing of a flow cuvette that can adapt to standard electroporator systems. The flow cuvette connected with a peristaltic pump was able to successfully electroporate 20 mL of medium containing microalgae cells in less than 5 min. Microalgae Scenedesmus almeriensis cells were transfected with a fluorescent siRNA oligo as well as magnetically transformed by introducing magnetic nanoparticles in their cytoplasm. The flow cuvette presented here offers a valid tool for the high-throughput transformation/transfection/transfer of both prokaryotic and eukaryotic organisms, especially suitable for bioreactor cultivation and other industrial biotechnological contexts.
      Citation: Magnetochemistry
      PubDate: 2022-11-04
      DOI: 10.3390/magnetochemistry8110147
      Issue No: Vol. 8, No. 11 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 148: A Comparative Investigation of
           Mechanical Properties of TiB2/Cr Multilayer Film by Indentation

    • Authors: Simeng Chen, Zhengtao Wu, Qimin Wang
      First page: 148
      Abstract: Alternating TiB2-dcMS and Cr-HiPIMS layers are used to fabricate TiB2/Cr multilayer films. Introducing a 5-nm-thick Cr interlayer deposited under a substrate bias of −60 V produces slight increases in both film hardness and elastic modulus. The TEM observation indicates that the Cr grains favor epitaxial growth on the TiB2 interlayer, forming a coherent TiB2/Cr interface. This improves hardness. Mechanic measurement by using AFM illustrates that the coherent interface increases the elastic modulus of the Cr up to ~280 GPa, which is significantly higher than bulk material.
      Citation: Magnetochemistry
      PubDate: 2022-11-07
      DOI: 10.3390/magnetochemistry8110148
      Issue No: Vol. 8, No. 11 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 149: Magnetic Properties and
           Microstructure of Ce-Cu-Al Low Melting Alloy Bonding Sm2Fe17N3 Magnet
           Fabricated by the Hot-Pressing Method

    • Authors: Jingwu Zheng, Shitong Yu, Heng Huang, Rongyao Li, Wei Cai, Haibo Chen, Juan Li, Liang Qiao, Yao Ying, Wangchang Li, Jing Yu, Shenglei Che
      First page: 149
      Abstract: Sm2Fe17N3 compounds, having excellent intrinsic magnetic properties, are prone to decomposition at high temperatures; thus, a low melting point metal binder is the key to prepare high performance bulk magnets at low temperatures. In this paper, a new low melting point alloy Ce72Cu28-xAlx was used as the binders, and high-performance Ce-based alloy bonding Sm2Fe17N3 magnets were realized by the hot-pressing method. The experimental results demonstrated that the content of Al in the Ce-based alloys had an important influence on the performance of the magnets. High performance Sm-Fe-N bonded magnets with remanence of 10.19 KGs and maximum magnetic energy product of 21.06 MGOe were achieved by using 5 wt.% Ce72Cu22Al6 alloy as a binder. At the same time, it was found that the Ce72Cu28-xAlx alloy has a lower density and better bonding effect than the common Zn binder. Its bonding magnets still have higher performance even with extremely high oxygen content. Therefore, Ce72Cu28-xAlx alloy with low melting point is a promising new rare earth-based alloy binder. If the oxygen content of the alloy powders could be reduced, higher performance Sm2Fe17N3 bonded magnets can be prepared.
      Citation: Magnetochemistry
      PubDate: 2022-11-07
      DOI: 10.3390/magnetochemistry8110149
      Issue No: Vol. 8, No. 11 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 150: Influence of Na/Mg Co-Doping in
           Tuning Microstructure, Transport, Optical, and Magnetic Properties of TiO2
           Compounds for Spintronics Applications

    • Authors: Radha Narzary, Bikash Dey, Santanu Sen, Bichitra Nanda Parida, Arunendu Mondal, Seenipandian Ravi, Sandeep Kumar Srivastava
      First page: 150
      Abstract: In recent years, researchers have been making a persistent effort to discover innovative and appropriate oxide materials that can be exploited in optoelectronics devices. The primary objective of this research is to study the effect of Na/Mg co-doping on microstructure, transport (dielectric and Hall Effect), optical and magnetic properties of Ti0.94-yNa0.06MgyO2 (y = 0–0.08) compounds that were synthesized using a solid-state route method. All the compounds have been crystallized to a single rutile phase, as reported by the XRD study. The elemental color mapping reveals that there is a consistent distribution of all of the elements across the compound. The XPS study suggests that Ti mostly resided in the Ti4+ oxidation state. The enhancement of the Mg co-doping concentration led to a decrease in the dielectric value as well as the AC conductivity of the material. In addition to this, it has been noted that these compounds have a low dielectric loss. The analyses of Nyquist plots reveal that the increase of Mg co-doping concentration led to a rise in the amount of relaxation that is non-Debye sort. This, in turn, caused a reduction in the amount of resistance exhibited by grains and grain boundaries. The Maxwell–Wagner model was used to conduct an analysis of the dielectric data, and the results indicated that the hopping of charge carriers is most likely to be responsible for the transport of electrical charges. From the optical properties’ measurement and analyses, it was noticed that the band gap had been slightly changed, but the transmittance value had increased from 81% for Ti0.94Na0.06O2 to 84% with an increase in Mg co-doping concentration. The Hall Effect analysis unequivocally pointed to the presence of p-type conductivity as well as an increased carrier density concentration. The room temperature magnetization versus field measurement indicates the ferromagnetic nature of the samples. Thus, the co-doping of Mg with Na in TiO2 leads to a narrowing of the band gap of TiO2 while tweaking the optical and transport properties. The studied materials can be utilized for spintronics and optoelectronics applications.
      Citation: Magnetochemistry
      PubDate: 2022-11-07
      DOI: 10.3390/magnetochemistry8110150
      Issue No: Vol. 8, No. 11 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 151: Effect of Ligand Substitution on
           Zero-Field Slow Magnetic Relaxation in Mononuclear Dy(III)
           β-Diketonate Complexes with Phenanthroline-Based Ligands

    • Authors: Egor V. Gorshkov, Denis V. Korchagin, Elena A. Yureva, Gennadii V. Shilov, Mikhail V. Zhidkov, Alexei I. Dmitriev, Nikolay N. Efimov, Andrew V. Palii, Sergey M. Aldoshin
      First page: 151
      Abstract: Herein, we report the synthesis, structure and magnetic properties of two mononuclear complexes of general formula [Dy(acac)3(L)], where L = 2,2-dimethyl-1,3-dioxolo[4,5-f][1,10] phenanthroline (1) or 1,10-phenanthroline-5,6-dione (2), and acac− = acetylacetonate anion. A distorted square-antiprismatic N2O6 environment around the central Dy(III) ion is formed by three acetylacetonate anions and a phenanthroline-type ligand. Both complexes display a single-molecule magnet (SMM) behavior at zero applied magnetic field. Modification of the peripheral part of ligands L provide substantial effects both on the magnetic relaxation barrier Ueff and on the quantum tunneling of magnetization (QTM). Ab initio quantum-chemical calculations are used to analyze the electronic structure and magnetic properties.
      Citation: Magnetochemistry
      PubDate: 2022-11-07
      DOI: 10.3390/magnetochemistry8110151
      Issue No: Vol. 8, No. 11 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 152: Effect of External Pressure on the
           Metal–Insulator Transition of the Organic Quasi-Two-Dimensional
           Metal κ-(BEDT-TTF)2Hg(SCN)2Br

    • Authors: Sergei I. Pesotskii, Rustem B. Lyubovskii, Gennady V. Shilov, Vladimir N. Zverev, Svetlana A. Torunova, Elena I. Zhilyaeva, Enric Canadell
      First page: 152
      Abstract: The metal–insulator transition in the organic quasi-two-dimensional metal κ-(BEDT-TTF)2Hg(SCN)2Br at TMI ≈ 90 K has been investigated. The crystal structure changes during this transition from monoclinic above TMI to triclinic below TMI. A theoretical study suggested that this phase transition should be of the metal-to-metal type and brings about a substantial change of the Fermi surface. Apparently, the electronic system in the triclinic phase is unstable toward a Mott insulating state, leading to the growth of the resistance when the temperature drops below TMI ≈ 90 K. The application of external pressure suppresses the Mott transition and restores the metallic electronic structure of the triclinic phase. The observed quantum oscillations of the magnetoresistance are in good agreement with the calculated Fermi surface for the triclinic phase, providing a plausible explanation for the puzzling behavior of κ-(BEDT-TTF)2Hg(SCN)2Br as a function of temperature and pressure around 100 K. The present study points out interesting differences in the structural and physical behaviors of the two room temperature isostructural salts of κ-(BEDT-TTF)2Hg(SCN)2X with X = Br, Cl.
      Citation: Magnetochemistry
      PubDate: 2022-11-08
      DOI: 10.3390/magnetochemistry8110152
      Issue No: Vol. 8, No. 11 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 153: Mononuclear Heptacoordinated 3d-Metal
           Helicates as a New Family of Single Ion Magnets

    • Authors: Yulia P. Tupolova, Denis V. Korchagin, Anastasya S. Andreeva, Valery V. Tkachev, Gennadii V. Shilov, Vladimir A. Lazarenko, Leonid D. Popov, Konstantin A. Babeshkin, Nikolay N. Efimov, Roman B. Morgunov, Andrei V. Palii, Stanislav P. Kubrin, Igor N. Shcherbakov, Sergey M. Aldoshin
      First page: 153
      Abstract: The series of Co(II), Fe(II), and Ni(II) mononuclear coordination compounds of [CoL(NCS)2]·3DMSO (1), [CoL(H2O)2](ClO4)2·DMSO (2), [CoL(H2O)(EtOH)][CoCl4]·2H2O (2a), [FeL(NCS)2]·DMSO (3), and [NiL(NCS)2]·CH3CN (4) composition (where L is 2,6-bis(1-(2-(4,6-dimethylpyrimidin-2-yl)hydrazineylidene)ethyl)pyridine), with an [MLA2] coordination unit (where A is a pair of apical monodentate ligands), was synthesized. In compounds 1, 2, 2a, and 3, the ligand L is pentadentate, and cobalt and iron ions are placed in a heavily distorted pentagonal pyramidal coordination environment, while in 4 the Ni(II) ion is hexacoordinated. Easy plane-type magnetic anisotropy (D = 13.69, 11.46, 19.5, and 6.2 cm−1 for 1, 2, 2a, and 4, respectively) was established for cobalt and nickel compounds, while easy axis-type magnetic anisotropy (D = −14.5 cm−1) was established for iron compound 3. The cobalt coordination compounds 1 and 2 show SIM behavior under a 1500 Oe external magnetic field, with effective magnetization reversal barriers of 65(1) and 60(1) K for 1 and 2, respectively. The combination of Orbach and Raman relaxation mechanisms was shown to adequately describe the temperature dependence of relaxation times for 1 and 2. CASSCF/NEVPT2 calculations were performed to model the parameters of the effective spin Hamiltonian for the compounds under study.
      Citation: Magnetochemistry
      PubDate: 2022-11-09
      DOI: 10.3390/magnetochemistry8110153
      Issue No: Vol. 8, No. 11 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 154: Interface Effects on Magnetic
           Anisotropy and Domain Wall Depinning Fields in Pt/Co/AlOx Films

    • Authors: Babu Ram Sankhi, Ujjal Lamichhane, Soumya Mandal, Ritesh Sachan, Emrah Turgut, Derek Meyers
      First page: 154
      Abstract: We report the dependence of the domain wall depinning field, domain wall velocity, including anisotropy direction, and magnetic properties on the oxidized aluminum thickness of perpendicularly magnetized asymmetric Pt/Co/AlOx trilayers. We also adopt the low-temperature magneto-transport measurement technique to investigate the amount of oxygen at the Co/AlOx interface of our magnetic thin films. At the lowest temperature of 25 K, it is found that the coercivity for the 5 nm aluminum thickness sample is very close to the average value and coercivity diminished above and below this critical aluminum thickness, hinting at a large variation in CoOx content at the interface. This tendency is also consistent with the modification of the depinning fields, coercive fields, and surface roughness measured at room temperature. Our results highlight an efficient way of controlling the depinning fields and other magnetic characteristics, which is important for stabilizing and driving magnetic spin textures and applicable to energy-efficient next-generation spintronics devices.
      Citation: Magnetochemistry
      PubDate: 2022-11-12
      DOI: 10.3390/magnetochemistry8110154
      Issue No: Vol. 8, No. 11 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 155: Impact of an Induced Magnetic Field
           on the Stagnation-Point Flow of a Water-Based Graphene Oxide Nanoparticle
           over a Movable Surface with Homogeneous–Heterogeneous and Chemical
           Reactions

    • Authors: Umair Khan, Aurang Zaib, Anuar Ishak, Abeer M. Alotaibi, Samia Elattar, Ioan Pop, Ahmed M. Abed
      First page: 155
      Abstract: Water has attracted plenty of attention as a lubricant for manufacturing due to the fact that it is inexpensive, environmentally friendly, and efficient. Because of their outstanding mechanical capabilities, water dispensability, and range of real applications, graphene oxide (GO) materials have the potential to augment the effectiveness of water lubrication. With this encouragement, we inspect the impact of induced magnetism on the fluid flow near a stagnation point dispended with water-based GO nanoparticles caused by a movable surface with a homogeneous–heterogeneous chemical reaction. The leading equations and their related boundary constraints are first transformed into a non-dimensional form through the utilization of the similarity technique. The consequent equations are then numerically solved by employing the bvp4c scheme. Those figures are used to exemplify the stimulation of the relevant constraints on the fluid flow, induced magnetic profiles, temperature profiles, concentration profiles, heat transfer, and friction factor. It is observed that the nanoparticle’s volume fraction enhances the heat transfer rate, as well as the friction factor. The heat transfer and friction factor escalate by almost 11.71% and 0.96% for the respective upper-branch solutions due to the larger impacts of nanoparticles’ volume fractions, while for the lower-branch solutions, they are augmented at about 21.8% and 0.66%, respectively. In addition, double solutions can be found in the limited values of a movable parameter.
      Citation: Magnetochemistry
      PubDate: 2022-11-12
      DOI: 10.3390/magnetochemistry8110155
      Issue No: Vol. 8, No. 11 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 156: On the Concurrent Bipartite
           Entanglement of a Spin-1 Heisenberg Diamond Cluster Developed for
           Tetranuclear Nickel Complexes

    • Authors: Azadeh Ghannadan, Katarína Karl’ová, Jozef Strečka
      First page: 156
      Abstract: The bipartite entanglement of a quantum spin-1 Heisenberg diamond cluster in the presence of the external magnetic field is quantified through the negativity, which is calculated for spin pairs from a diagonal and a side of the diamond spin cluster taking into consideration two different coupling constants. The magnetic field may cause a few crossings of energy levels of the spin-1 Heisenberg diamond cluster, which is responsible at low enough temperatures for a stepwise dependence of the negativity on the magnetic field accompanied with a drop of the negativity at respective magnetic-field-driven transitions due to emergence of mixed states. It is shown that the bipartite entanglement between spin pairs on a diagonal and a side of the diamond spin cluster is concurrent although they may eventually become both nonzero albeit not fully saturated. It is predicted that the tetranuclear nickel complex [Ni4(μ-CO3)2(aetpy)8](ClO4)4 (aetpy = 2-aminoethyl-pyridine), which represents an experimental realization of the spin-1 Heisenberg diamond cluster with two different antiferromagnetic coupling constants, exhibits a substantial bipartite entanglement between two spin-1 Ni2+ magnetic ions from a shorter diagonal of the diamond spin cluster up to temperatures approximately about 50 K and up to magnetic fields about 70 T.
      Citation: Magnetochemistry
      PubDate: 2022-11-12
      DOI: 10.3390/magnetochemistry8110156
      Issue No: Vol. 8, No. 11 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 157: An Improved 3D Magnetization
           Inversion Based on Smoothness Constraints in Spherical Coordinates

    • Authors: Liang Zhang, Guangyin Lu, Ziqiang Zhu, Shujin Cao
      First page: 157
      Abstract: In the inverse problem, the traditional way to obtain a stable solution is based on the maximum smoothness criteria. However, this approach cannot generate clearer and more focused images. In this study, we propose an improved inversion method based on the smoothness constraints. In the algorithm, the model weighting functions are updated by adding a model’s total gradient module matrix, which can effectively constrain the boundary of the recovery model in the iterative operation. We invert the 3D magnetization intensity for the three-component magnetic data in the spatial domain by spherical coordinates. The preconditional conjugate gradient algorithm is introduced to improve the efficiency of the solutions. We design two sets of synthetic examples to evaluate the inversion effects, which show that the improved method is more reliable than the smoothness constraint method. The boundary of the magnetic bodies is more precise, and the magnetization ranges are more focused. The method does not rely on the initial model and is suitable for magnetic vector data inversion. We also apply the algorithm to a set of Dabie orogen three-component magnetic data derived from a geomagnetic field model and verify the effectiveness of the inversion method.
      Citation: Magnetochemistry
      PubDate: 2022-11-14
      DOI: 10.3390/magnetochemistry8110157
      Issue No: Vol. 8, No. 11 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 158: Effect of Substrate on
           One-Dimensional Multiferroic Properties

    • Authors: Ivan Maltsev, Igor Bychkov
      First page: 158
      Abstract: We present a theoretical study of the substrate influence on the electrical and magnetic properties of a one-dimensional multiferroic. We used a one-dimensional axial next-nearest neighbor Ising model (1D ANNNI model). The effect of the substrate was modeled using the periodic Frenkel–Kontorova potential. It is shown that the periodic potential of the substrate reduces the polarization of the multiferroic at low temperatures. The substrate potential significantly affects the structural changes near the magnetic phase transition temperature.
      Citation: Magnetochemistry
      PubDate: 2022-11-16
      DOI: 10.3390/magnetochemistry8110158
      Issue No: Vol. 8, No. 11 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 159: Modelling of Magnetic Stray Fields in
           Multilayer Magnetic Films with In-Plane or Perpendicular Anisotropy

    • Authors: Sai Zhou, Yiyue Wang, Yaowen Liu
      First page: 159
      Abstract: The magnetic stray field is an unavoidable consequence of magnetic multilayers, which may have a significant influence on the performance of spintronic devices. Based on Maxwell’s magnetostatics theory, here we numerically calculated the distributions of magnetic stray fields and self-demagnetizing fields in a series of patterned multilayer thin-film structures with either an in-plane or a perpendicularly magnetized ferromagnetic layer. The stray field above the ferromagnetic layer is inhomogeneous, showing the dramatic changes near the sample edge, but the uniformity in the center region could be improved with the increasing sample size. The stray field strength tends to zero for large samples, increases with the increase in the hard-layer thickness, and decreases with the increase in the distance D away from the ferromagnetic layer. In the multilayer samples, the separately simulated stray field and self-demagnetizing field within the soft layer agree well with the classic magnetostatic relationship of B=μ0(Hd+M). For the in-plane magnetized trilayer sample, the magnetic-flux density within the soft ferromagnetic layer slightly decreases in the antiparallel magnetization alignment and increases in the parallel alignment state with the increase in the intermediate non-magnetic-layer thickness. In contrast, for the sample with the perpendicular magnetization, the magnetic-flux density decreases as the non-magnetic layer is thickened for both the antiparallel and parallel state. This study may provide a theoretical basis for the design of thin-film spintronic devices.
      Citation: Magnetochemistry
      PubDate: 2022-11-19
      DOI: 10.3390/magnetochemistry8110159
      Issue No: Vol. 8, No. 11 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 160: PAN—Composite
           Electrospun-Fibers Decorated with Magnetite Nanoparticles

    • Authors: Zulkhair Mansurov, Gaukhar Smagulova, Bayan Kaidar, Aigerim Imash, Aidos Lesbayev
      First page: 160
      Abstract: The results of the synthesis of PAN(polyacrylonitrile)-magnetite composite fibers using the electrospinning method are presented. The electrospinning installation included a rotating drum collector for collecting fibers. Magnetite nanoparticles were synthesized using chemical condensation from an iron chloride solution. It was shown that homogeneous Fe3O4 magnetite nanoparticles with particle sizes of 6–16 nm could be synthesized using this method. Magnetite nanoparticles were investigated using X-ray diffraction analyses and transmission electron microscopy. Based on magnetite nanoparticles, composite PAN/magnetite fibers were obtained through electrospinning. The obtained composite fibers were investigated using scanning electron microscopy, X-ray diffraction analyses, and elemental analyses. It was shown that the magnetite nanoparticles were uniformly distributed on the surface of the fibers. A comparison of PAN fibers without any added magnetite to PAN/magnetite fibers showed that the addition of magnetite led to a decrease in the value of the fiber diameter at the same polymer concentration and under the same electrospinning process conditions.
      Citation: Magnetochemistry
      PubDate: 2022-11-21
      DOI: 10.3390/magnetochemistry8110160
      Issue No: Vol. 8, No. 11 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 161: Molarity Effects of Fe and NaOH on
           Synthesis and Characterisation of Magnetite (Fe3O4) Nanoparticles for
           Potential Application in Magnetic Hyperthermia Therapy

    • Authors: Lokesh Srinath Ganapathe, Jamal Kazmi, Mohd Ambri Mohamed, Dilla Duryha Berhanuddin
      First page: 161
      Abstract: In this study, the effect of molarity on the structural, magnetic, and heat dissipation properties of magnetite nanoparticles (MNPs) was investigated to optimise the parameters for potential application in magnetic hyperthermia therapy (MHT). MHT works based on the principle of local temperature rise at the tumour site by magnetic iron oxide nanoparticles (MIONPs) with the application of an alternating magnetic field. MHT is a safe method for cancer treatment and has minimal or no side effects. Magnetite (Fe3O4) is the best material among MIONPs to be applied in local MHT due to its biocompatibility and high saturation magnetisation value. MNPs were prepared by co-precipitation at varying molarity. Structural characterisation was performed via X-ray powder diffraction (XRD) for crystalline structure analysis and field-emission scanning electron microscopy (FESEM) for morphology and particle size analysis. Measurement of the magnetic properties of the as-synthesised MNPs was carried out using a vibrating sample magnetometer (VSM). Power loss (P) was determined theoretically. The increase in molarity resulted in significant effects on the structural, magnetic, and heat dissipation properties of MNPs. The particle size and saturation magnetisation (Ms) decreased with the gradual addition of base but increased, together with crystallinity, with the gradual addition of iron source. M3 recorded the smallest crystalline size at 3.559 nm. The sample with the highest molarity (M4) displayed the highest heat generation capacity with a p value of up to 0.4056 W/g. High p values at the nano-scale are crucial, especially in local MHT, for effective heat generation, thus proving the importance of molarity as a vital parameter during MNP synthesis.
      Citation: Magnetochemistry
      PubDate: 2022-11-21
      DOI: 10.3390/magnetochemistry8110161
      Issue No: Vol. 8, No. 11 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 131: Biological Applications of
           Silica-Based Nanoparticles

    • Authors: Franciele da Silva Bruckmann, Franciane Batista Nunes, Theodoro da Rosa Salles, Camila Franco, Francine Carla Cadoná, Cristiano Rodrigo Bohn Rhoden
      First page: 131
      Abstract: Silica nanoparticles have been widely explored in biomedical applications, mainly related to drug delivery and cancer treatment. These nanoparticles have excellent properties, high biocompatibility, chemical and thermal stability, and ease of functionalization. Moreover, silica is used to coat magnetic nanoparticles protecting against acid leaching and aggregation as well as increasing cytocompatibility. This review reports the recent advances of silica-based magnetic nanoparticles focusing on drug delivery, drug target systems, and their use in magnetohyperthermia and magnetic resonance imaging. Notwithstanding, the application in other biomedical fields is also reported and discussed. Finally, this work provides an overview of the challenges and perspectives related to the use of silica-based magnetic nanoparticles in the biomedical field.
      Citation: Magnetochemistry
      PubDate: 2022-10-18
      DOI: 10.3390/magnetochemistry8100131
      Issue No: Vol. 8, No. 10 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 132: Binuclear Nickel Complexes of a New
           Di(hydroxyphenyl)imidazolate

    • Authors: Igor A. Nikovskiy, Kseniia M. Karnaukh, Dmitry Yu. Aleshin, Kirill A. Spiridonov, Anastasia A. Danshina, Yulia V. Nelyubina, Alexander V. Polezhaev, Valentin V. Novikov
      First page: 132
      Abstract: Here, we report a new di(hydroxyphenyl)imidazolate ligand with an N2O2 donor set synthesized by a modified Debus–Radziszewski procedure. Its binuclear nickel(II) complexes feature a weak antiferromagnetic interaction with J12 = −3.16 cm−1 between the two nickel(II) ions identified by magnetometry measurements. As follows from cyclic voltammetry experiments and DFT calculations, they undergo ligand-centered oxidation via the formation of cation radicals with short lifetimes that can be potentially stabilized by bulkier t-butyl groups in the ortho-positions of the ligand. The reported ligand widens the range of the building blocks available to molecular magnetism community and thus provides new ways to the design of magnetic materials with switchable properties.
      Citation: Magnetochemistry
      PubDate: 2022-10-18
      DOI: 10.3390/magnetochemistry8100132
      Issue No: Vol. 8, No. 10 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 133: The Synthesis of
           Metal–Organic-Framework-Based Ternary Nanocomposite for the
           Adsorption of Organic Dyes from Aqueous Solutions

    • Authors: Norah Salem Alsaiari, Haitham Osman, Abdelfattah Amari, Mohamed A. Tahoon
      First page: 133
      Abstract: In the present study, a ternary magnetic nanocomposite (SiO2/MnFe2O4/ZIF-8) was synthesized via the embedding of the SiO2/MnFe2O4 nanocomposite within the metal–organic framework (ZIF-8). The synthesized nanocomposite was characterized using suitable techniques including FT-IR, XRD, SEM, TEM, VSM, and BET. The nanocomposite showed a high surface area (SBET = 831 m2·g−1) and superparamagnetic behavior (23.7 emu·g−1). All characterization techniques confirmed the successful combination of three nanocomposite parts (MnFe2O4, SiO2, and ZIF-8). The nanocomposite was examined for the adsorption of organic dyes, malachite green (MG) and methyl red (MR), from aqueous solutions. The adsorption conditions including ionic strength, contact time, pH, and adsorbent dosage were optimized by studying their change effect. The SiO2/MnFe2O4/ZIF-8 nanocomposite showed high adsorption capacities (1000.03 and 1111.12 mg/g) for the removal of MG and MR, respectively, from water. The isotherm and kinetics studies indicated that the adsorption of MG and MR dyes on the surface of the SiO2/MnFe2O4/ZIF-8 nanocomposite followed the Langmuir isotherm model and pseudo-second-order kinetic model, suggesting the monolayer chemisorption mechanism. The reusability study of up to five successive cycles indicated the successful reuse of the SiO2/MnFe2O4/ZIF-8 adsorbent for dye removal from wastewater. The comparison of the present adsorbent to the previously reported adsorbents indicated that it is a promising adsorbent for dye adsorption from wastewater and must be investigated in the future for the removal of additional pollutants.
      Citation: Magnetochemistry
      PubDate: 2022-10-19
      DOI: 10.3390/magnetochemistry8100133
      Issue No: Vol. 8, No. 10 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 134: The Effect of Obliquely Sputtered Cu
           Underlayers with Different Thicknesses on the Magnetic Properties of 50 nm
           Ni80Fe20 Thin Films

    • Authors: Xiaoyu Li, Yunshi Jiang, Huan Yan, Tianming Li, Lu Zhang, Zhihong Zhang, Xian Guan, Min Chen, Jiaoyin Wang, Yihan Pu, Genzhai Peng, Mengjia Wang
      First page: 134
      Abstract: The magnetic properties of 50 nm Ni80Fe20 deposited on Cu underlayers with different thicknesses by obliquely sputtering were studied. It was found that the in-plane uniaxial magnetic anisotropy (IPUMA) of the Ni80Fe20 film can be induced by the obliquely sputtered Cu underlayer deposited under the NiFe layer. The IPUMA field of NiFe film varies between 20 Oe and 40 Oe when the thickness of Cu underlayer varies from 5 nm to 50 nm. The permeability spectrum results show that the damping factor increases with increasing Cu underlayer thickness. This indicates that changing the thickness of the Cu underlayer of obliquely sputtering is an effective method to adjust the damping factor in the dynamic magnetization process of Ni80Fe20 thin films.
      Citation: Magnetochemistry
      PubDate: 2022-10-19
      DOI: 10.3390/magnetochemistry8100134
      Issue No: Vol. 8, No. 10 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 135: Strain-Magnetooptics in Single
           Crystals of CoFe2O4

    • Authors: Yurii Sukhorukov, Andrei Telegin, Nikolay Bebenin, Vladimir Bessonov, Sergei Naumov, Denis Shishkin, Aleksandr Nosov
      First page: 135
      Abstract: The strain-magnetooptical properties of single crystals of the ferrimagnetic spinel CoFe2O4, which reflect a correlation between optical properties (magnetoabsorption and magnetoreflection) and magnetostriction, have been studied in the infrared spectral range. The conditions for the observation of the strain-magnetooptics are specified and physical mechanisms responsible for these effects in the spinel are explained.
      Citation: Magnetochemistry
      PubDate: 2022-10-20
      DOI: 10.3390/magnetochemistry8100135
      Issue No: Vol. 8, No. 10 (2022)
       
  • Magnetochemistry, Vol. 8, Pages 136: Martensitic Transformation, Magnetic
           and Mechanical Characteristics in Unidirectional Ni–Mn–Sn
           Heusler Alloy

    • Authors: Haodong Sun, Chao Jing, Hui Zeng, Yuan Su, Siyuan Yang, Yuanlei Zhang, Tarek Bachagha, Ting Zhou, Long Hou, Wei Ren
      First page: 136
      Abstract: A textured structure of Ni–Mn–Sn Heusler alloy with [001] preferred orientation has been grown by the directional solidification method. The crystal exhibits a single austenite phase L21 cubic structure (a = 5.997 Å) at room temperature. Magnetization and electronic transport measurements reveal the phase transformation characteristics. The maximum values of magnetic entropy change determined by Maxwell’s thermodynamic relation during the structural and magnetic phase transformations are 3.5 J/kg·K and −4.1 J/kg·K, and the total effective refrigerant capacity reaches about 314 J/kg (5 T). The evident reduction in hysteresis loss and broad operating temperature window provide a greater prospect for improving the cyclic stability of refrigeration and optimizing the application of such a magnetic refrigeration material. Both magnetoresistance (−18%, 5 T) and exchange bias field (302 Oe, 2 K) have also been investigated to understand the nature of phase transformations and exchange interactions. Furthermore, as the material exhibits excellent mechanical properties (1068 MPa, 9.0%), our experimental results provide a new reference for the application of Ni–Mn–Sn Heusler alloys.
      Citation: Magnetochemistry
      PubDate: 2022-10-21
      DOI: 10.3390/magnetochemistry8100136
      Issue No: Vol. 8, No. 10 (2022)
       
 
JournalTOCs
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
Email: journaltocs@hw.ac.uk
Tel: +00 44 (0)131 4513762
 


Your IP address: 3.236.70.233
 
Home (Search)
API
About JournalTOCs
News (blog, publications)
JournalTOCs on Twitter   JournalTOCs on Facebook

JournalTOCs © 2009-