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Showing 1 - 20 of 20 Journals sorted alphabetically
Acta Crystallographica Section A: Foundations and Advances     Hybrid Journal   (Followers: 8)
Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials     Hybrid Journal   (Followers: 6)
Acta Crystallographica Section C: Structural Chemistry     Hybrid Journal   (Followers: 4)
Acta Crystallographica Section D : Biological Crystallography     Hybrid Journal   (Followers: 7)
Acta Crystallographica Section E : Crystallographic Communications     Open Access   (Followers: 3)
Acta Crystallographica Section F: Structural Biology Communications     Hybrid Journal   (Followers: 8)
Crystal Growth & Design     Hybrid Journal   (Followers: 13)
Crystal Research and Technology     Hybrid Journal   (Followers: 6)
Crystallography Reports     Hybrid Journal   (Followers: 2)
Crystallography Reviews     Hybrid Journal   (Followers: 3)
IUCrJ     Open Access  
Journal of Applied Crystallography     Hybrid Journal   (Followers: 7)
Journal of Chemical Crystallography     Hybrid Journal   (Followers: 2)
Journal of Crystal Growth     Hybrid Journal   (Followers: 6)
Liquid Crystals     Hybrid Journal   (Followers: 1)
Liquid Crystals Today     Hybrid Journal   (Followers: 1)
Materials and Devices     Open Access  
Molecular Crystals and Liquid Crystals     Hybrid Journal   (Followers: 1)
Polymer crystallization     Hybrid Journal  
Progress in Crystal Growth and Characterization of Materials     Full-text available via subscription   (Followers: 8)
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Crystals
Number of Followers: 1  

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ISSN (Print) 2073-4352
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  • Crystals, Vol. 12, Pages 1: Director Fluctuations in Two-Dimensional
           Liquid Crystal Disclinations

    • Authors: Olaf Stenull, Tom C. Lubensky
      First page: 1
      Abstract: We present analytical calculations of the energies and eigenfunctions of all normal modes of excitation of charge +1 two-dimensional splay (bend) disclinations confined to an annular region with inner radius R1 and outer radius R2 and with perpendicular (tangential) boundary conditions on the region’s inner and outer perimeters. Defects such as these appear in islands in smectic-C films and can in principle be created in bolaamphiphilic nematic films. Under perpendicular boundary conditions on the two surfaces and when the ratio β=Ks/Kb of the splay to bend 2D Frank constants is less than one, the splay configuration is stable for all values μ=R2/R1. When β>1, the splay configuration is stable only for μ less than a critical value μc(β), becoming unstable to a “spiral” mixed splay-bend configuration for μ>μc. The same behavior occurs in trapped bend defects with tangential boundary conditions but with Ks and Kb interchanged. By calculating free energies, we verify that the transition from a splay or bend configuration to a mixed one is continuous. We discuss the differences between our calculations that yield expressions for experimentally observable excitation energies and other calculations that produce the same critical points and spiral configurations as ours but not the same excitation energies. We also calculate measurable correlation functions and associated decay times of angular fluctuations.
      Citation: Crystals
      PubDate: 2021-12-21
      DOI: 10.3390/cryst12010001
      Issue No: Vol. 12, No. 1 (2021)
       
  • Crystals, Vol. 12, Pages 2: Electronic Heat Capacity and Lattice Softening
           of Partially Deuterated Compounds of κ-(BEDT-TTF)2Cu[N(CN)2]Br

    • Authors: Yuki Matsumura, Shusaku Imajo, Satoshi Yamashita, Hiroki Akutsu, Yasuhiro Nakazawa
      First page: 2
      Abstract: Thermodynamic investigation by calorimetric measurements of the layered organic superconductors, κ-(BEDT-TTF)2Cu[N(CN)2]Br and its partially deuterated compounds of κ-(d[2,2]-BEDT-TTF)2Cu[N(CN)2]Br and κ-(d[3,3]-BEDT-TTF)2Cu[N(CN)2]Br, performed in a wide temperature range is reported. The latter two compounds were located near the metal–insulator boundary in the dimer-Mott phase diagram. From the comparison of the temperature dependences of their heat capacities, we indicated that lattice heat capacities of the partially deuterated compounds were larger than that of the pristine compound below about 40 K. This feature probably related to the lattice softening was discussed also by the sound velocity measurement, in which the dip-like structures of the Δv/v were observed. We also discussed the variation of the electronic heat capacity under magnetic fields. From the heat capacity data at magnetic fields up to 6 T, we evaluated that the normal-state γ value of the partially deuterated compound, κ-(d[3,3]-BEDT-TTF)2Cu[N(CN)2]Br, was about 3.1 mJ K−2 mol−1. Under the magnetic fields higher than 3.0 T, we observed that the magnetic-field insulating state was induced due to the instability of the mid-gap electronic state peculiar for the two-dimensional dimer-Mott system. Even though the volume fraction was much reduced, the heat capacity of κ-(d[3,3]-BEDT-TTF)2Cu[N(CN)2]Br showed a small hump structure probably related to the strong coupling feature of the superconductivity near the boundary.
      Citation: Crystals
      PubDate: 2021-12-21
      DOI: 10.3390/cryst12010002
      Issue No: Vol. 12, No. 1 (2021)
       
  • Crystals, Vol. 12, Pages 3: Laboratory X-ray Microscopy Study of
           Microcrack Evolution in a Novel Sodium Iron Titanate-Based Cathode
           Material for Li-Ion Batteries

    • Authors: Viktor Shapovalov, Kristina Kutukova, Sebastian Maletti, Christian Heubner, Vera Butova, Igor Shukaev, Alexander Guda, Alexander Soldatov, Ehrenfried Zschech
      First page: 3
      Abstract: The long-term performance of batteries depends strongly on the 3D morphology of electrode materials. Morphological changes, i.e., particle fracture and surface deterioration, are among the most prominent sources of electrode degradation. A profound understanding of the fracture mechanics of electrode materials in micro- and nanoscale dimensions requires the use of advanced in situ and operando techniques. In this paper, we demonstrate the capabilities of laboratory X-ray microscopy and nano X-ray computed tomography (nano-XCT) for the non-destructive study of the electrode material’s 3D morphology and defects, such as microcracks, at sub-micron resolution. We investigate the morphology of Na0.9Fe0.45Ti1.55O4 sodium iron titanate (NFTO) cathode material in Li-ion batteries using laboratory-based in situ and operando X-ray microscopy. The impact of the morphology on the degradation of battery materials, particularly the size- and density-dependence of the fracture behavior of the particles, is revealed based on a semi-quantitative analysis of the formation and propagation of microcracks in particles. Finally, we discuss design concepts of the operando cells for the study of electrochemical processes.
      Citation: Crystals
      PubDate: 2021-12-21
      DOI: 10.3390/cryst12010003
      Issue No: Vol. 12, No. 1 (2021)
       
  • Crystals, Vol. 12, Pages 4: The Third-Order Elastic Constants and
           Mechanical Properties of 30° Partial Dislocation in Germanium: A Study
           from the First-Principles Calculations and the Improved
           Peierls−Nabarro Model

    • Authors: Huili Zhang, Defang Lu, Yu Sun, Yunchang Fu, Lumei Tong
      First page: 4
      Abstract: The elastic constants, core width and Peierls stress of partial dislocation in germanium has been investigated based on the first-principles calculations and the improved Peierls−Nabarro model. Our results suggest that the predictions of lattice constant and elastic constants given by LDA are in better agreement with experiment results. While the lattice constant is overestimated at about 2.4% and most elastic constants are underestimated at about 20% by the GGA method. Furthermore, when the applied deformation is larger than 2%, the nonlinear elastic effects should be considered. And with the Lagrangian strains up to 8%, taking into account the third-order terms in the energy expansion is sufficient. Except the original γ—surface generally used before (given by the first-principles calculations directly), the effective γ—surface proposed by Kamimura et al. derived from the original one is also used to study the Peierls stress. The research results show that when the intrinsic−stacking−fault energy (ISFE) is very low relative to the unstable−stacking−fault energy (USFE), the difference between the original γ—surface and the effective γ—surface is inapparent and there is nearly no difference between the results of Peierls stresses calculated from these two kinds of γ—surfaces. As a result, the original γ—surface can be directly used to study the core width and Peierls stress when the ratio of ISFE to the USFE is small. Since the negligence of the discrete effect and the contribution of strain energy to the dislocation energy, the Peierls stress given by the classical Peierls−Nabarro model is about one order of magnitude larger than that given by the improved Peierls−Nabarro model. The result of Peierls stress estimated by the improved Peierls−Nabarro model agrees well with the 2~3 GPa reported in the book of Solid State Physics edited by F. Seitz and D. Turnbull.
      Citation: Crystals
      PubDate: 2021-12-21
      DOI: 10.3390/cryst12010004
      Issue No: Vol. 12, No. 1 (2021)
       
  • Crystals, Vol. 12, Pages 5: [3+2] Cycloaddition Reaction for the
           Stereoselective Synthesis of a New Spirooxindole Compound Grafted
           Imidazo[2,1-b]thiazole Scaffold: Crystal Structure and Computational Study
           

    • Authors: Mezna Saleh Altowyan, Saied M. Soliman, Matti Haukka, Nora Hamad Al-Shaalan, Alkharboush A. Aminah, Assem Barakat
      First page: 5
      Abstract: A new spirooxindole hybrid engrafted imidazo[2,1-b]thiazole core structure was designed and achieved via [3+2] cycloaddition reaction approach. One multi-component reaction between the ethylene derivative based imidazo[2,1-b]thiazole scaffold with 6-Cl-isatin and the secondary amine under heat conditions afforded the desired compound in a stereoselective manner. The relative absolute configuration was assigned based on single-crystal X-ray diffraction analysis. Hirshfeld calculations for 4 revealed the importance of the H…H (36.8%), H…C (22.9%), Cl…H (10.4%) and S…H (6.6%), as well as the O…H (4.7%), N…H (5.3%), Cl…C (1.6%), Cl…O (1.0%) and N…O (0.5%) contacts in the crystal stability. DFT calculations showed excellent straight-line correlations (R2 = 0.9776–0.9962) between the calculated and experimental geometric parameters. The compound has polar nature (3.1664 Debye). TD-DFT and GIAO calculations were used to assign and correlate the experimental UV-Vis and NMR spectra, respectively.
      Citation: Crystals
      PubDate: 2021-12-21
      DOI: 10.3390/cryst12010005
      Issue No: Vol. 12, No. 1 (2021)
       
  • Crystals, Vol. 12, Pages 6: Synthesis of Unexpected Dimethyl
           2-(4-Chlorophenyl)-2,3-dihydropyrrolo[2,1-a]isoquinoline-1,3-dicarboxylate
           via Hydrolysis/Cycloaddition/Elimination Cascades: Single Crystal X-ray
           and Chemical Structure Insights

    • Authors: Mezna Saleh Altowyan, Saied M. Soliman, Matti Haukka, Nora H. Al-Shaalan, Aminah A. Alkharboush, Assem Barakat
      First page: 6
      Abstract: Hydrolysis/[3 + 2] cycloaddition/elimination cascades employed for the synthesis of unexpected tricyclic compound derived from isoquinoline. Reaction of ethylene derivative 1 with the isoquinoline ester iminium ion 2 in alkaline medium (MeOH/NEt3) under reflux for 1 h resulted in the formation of the fused pyrrolo[2,1-a]isoquinoline derivative 3. Its structure was elucidated by X-ray single crystal and other spectrophotometric tools. Hirshfeld calculations for 3 and its crystal structure analysis revealed the importance of the short O…H (19.1%) contacts and the relatively long H…C (17.1%), Cl…H (10.6%) and C…C (6.1%) interactions in the molecular packing. DFT calculations were used to compute the electronic and spectroscopic properties of the studied system. The studied compound has polar nature (3.5953 Debye). TD-DFT calculations assigned the shortest wavelength band (220 nm) to the HOMO−1→LUMO+2 (57%), HOMO−1→LUMO+4 (14%) mixed excitations. The calculated NMR chemical shifts correlated very well with the experimental data (R2 = 0.93–0.94).
      Citation: Crystals
      PubDate: 2021-12-21
      DOI: 10.3390/cryst12010006
      Issue No: Vol. 12, No. 1 (2021)
       
  • Crystals, Vol. 12, Pages 7: Phase Stability, Elastic Modulus and Elastic
           Anisotropy of X Doped (X = Zn, Zr and Ag) Al3Li: Insight from
           First-Principles Calculations

    • Authors: Jinzhong Tian, Yuhong Zhao, Shengjie Ma, Hua Hou
      First page: 7
      Abstract: In present work, the effects of alloying elements X (X = Zn, Zr and Ag) doping on the phase stability, elastic properties, anisotropy and Debye temperature of Al3Li were studied by the first-principles method. Results showed that pure and doped Al3Li can exist and be stable at 0 K. Zn and Ag elements preferentially occupy the Al sites and Zr elements tend to occupy the Li sites. All the Cij obey the mechanical stability criteria, indicating the mechanical stability of these compounds. The overall anisotropy decreases in the following order: Al23Li8Ag > Al3Li > Al23Li8Zn > Al24Li7Zr, which shows that the addition of Zn and Zr has a positive effect on reducing the anisotropy of Al3Li. The shear anisotropic factors for Zn and Zr doped Al3Li are very close to one, meaning that elastic moduli do not strongly depend on different shear planes. For pure and doped Al3Li phase, the transverse sound velocities νt1 and νt2 among the three directions are smaller than the longitudinal sound velocity νl. Moreover, only the addition of Zn is beneficial to increasing the ΘD of Al3Li among the three elements.
      Citation: Crystals
      PubDate: 2021-12-21
      DOI: 10.3390/cryst12010007
      Issue No: Vol. 12, No. 1 (2021)
       
  • Crystals, Vol. 12, Pages 8: Toward Precise n-Type Doping Control in
           MOVPE-Grown β-Ga2O3 Thin Films by Deep-Learning Approach

    • Authors: Ta-Shun Chou, Saud Bin Anooz, Raimund Grüneberg, Klaus Irmscher, Natasha Dropka, Jana Rehm, Thi Thuy Vi Tran, Wolfram Miller, Palvan Seyidov, Martin Albrecht, Andreas Popp
      First page: 8
      Abstract: In this work, we train a hybrid deep-learning model (fDNN, Forest Deep Neural Network) to predict the doping level measured from the Hall Effect measurement at room temperature and to investigate the doping behavior of Si dopant in both (100) and (010) β-Ga2O3 thin film grown by the metalorganic vapor phase epitaxy (MOVPE). The model reveals that a hidden parameter, the Si supplied per nm (mol/nm), has a dominant influence on the doping process compared with other process parameters. An empirical relation is concluded from this model to estimate the doping level of the grown film with the Si supplied per nm (mol/nm) as the primary variable for both (100) and (010) β-Ga2O3 thin film. The outcome of the work indicates the similarity between the doping behavior of (100) and (010) β-Ga2O3 thin film via MOVPE and the generality of the results to different deposition systems.
      Citation: Crystals
      PubDate: 2021-12-21
      DOI: 10.3390/cryst12010008
      Issue No: Vol. 12, No. 1 (2021)
       
  • Crystals, Vol. 12, Pages 9: Exploring High-Pressure Transformations in
           Low-Z (H2, Ne) Hydrates at Low Temperatures

    • Authors: Paulo H. B. Brant Carvalho, Amber Mace, Inna Martha Nangoi, Alexandre A. Leitão, Chris A. Tulk, Jamie J. Molaison, Ove Andersson, Alexander P. Lyubartsev, Ulrich Häussermann
      First page: 9
      Abstract: The high pressure structural behavior of H2 and Ne clathrate hydrates with approximate composition H2/Ne·~4H2O and featuring cubic structure II (CS-II) was investigated by neutron powder diffraction using the deuterated analogues at ~95 K. CS-II hydrogen hydrate transforms gradually to isocompositional C1 phase (filled ice II) at around 1.1 GPa but may be metastably retained up to 2.2 GPa. Above 3 GPa a gradual decomposition into C2 phase (H2·H2O, filled ice Ic) and ice VIII’ takes place. Upon heating to 200 K the CS-II to C1 transition completes instantly whereas C1 decomposition appears sluggish also at 200 K. C1 was observed metastably up to 8 GPa. At 95 K C1 and C2 hydrogen hydrate can be retained below 1 GPa and yield ice II and ice Ic, respectively, upon complete release of pressure. In contrast, CS-II neon hydrate undergoes pressure-induced amorphization at 1.9 GPa, thus following the general trend for noble gas clathrate hydrates. Upon heating to 200 K amorphous Ne hydrate crystallizes as a mixture of previously unreported C2 hydrate and ice VIII’.
      Citation: Crystals
      PubDate: 2021-12-21
      DOI: 10.3390/cryst12010009
      Issue No: Vol. 12, No. 1 (2021)
       
  • Crystals, Vol. 12, Pages 10: Optimization of the Physical and Mechanical
           Properties of Grouting Material for Non-Soil-Squeezing PHC Pipe Pile

    • Authors: Zhenkun Hou, Mengxiong Tang, Shihua Liang, Yi Zhu
      First page: 10
      Abstract: The physical and mechanical properties of grouting materials greatly affect the friction resistance and the bearing performance of a non-soil-squeezing PHC pipe pile. Orthogonal tests for four factors at five levels were carried out to optimize the proportion of the water–cement mixture by using Portland cement as a raw material and a water-reducing agent, expansion agent and early-strength agent as additives. The following conclusions were obtained: (1) Both the water–cement ratio and the dosage of water-reducing agent are positively correlated with the fluidity of the water–cement mixture and have the greatest influence on the fluidity, followed by the expansion agent and early-strength agent. The saturation point of the water-reducing agent is 1.5%. (2) The strength of the grouting body decreases linearly with the increase of the water–cement ratio, and the dosage of the water-reducing agent has no obvious effect on the strength. As the dosage of expansion agent increases, the strength of the grouting body decreases rapidly. The expansion agent mainly plays a key role in the middle and late stages of the hardening process of the slurry. Early-strength agents have a greater impact on the early strength, but less on the later strength. When the slurry is solidified for 3 h, the early-strength agent has the greatest impact on the strength with an optimal dosage of 5%. (3) The volume of the grouting body has an inverse relationship with the water–cement ratio, and the optimal amount of expansion agent is 12%. The incorporation of an expansion agent makes the volume increase of the grouting body exceed the volume shrinkage ratio caused by the hardening of the grouting body with a curing time of more than 3 days, ensuring a slight increase in the volume of the grouting body. After 3 days, even though the effect of the expansion agent is gradually weakened, it can still ensure that the volume of the grouting body does not shrink. With the increase of the amount of water-reducing agent, the volume of the grouting body gradually decreases. When the amount of water-reducing agent exceeds 1.5%, the volume of the grouting body no longer decreases. (4) The early-strength agent has almost no effect on the volume of the grouting body. When the curing time is 3 h, the water–cement ratio has the greatest influence on the volume of the grouting body, followed by the water-reducing agent, and, finally, the expansion agent. After 3 h, the water–cement ratio still has the greatest influence, and the influence of the expansion agent gradually exceeds that of the water-reducing agent. The water-reducing agent mainly affects the volume of the grouting body in the water separation stage, and the expansion agent mainly plays a role in the middle and late stages of the slurry solidification. After optimized ratio analysis, the fluidity of the water–cement mixture can be improved, the volume shrinkage ratio rate can be lowered and the early strength can be increased.
      Citation: Crystals
      PubDate: 2021-12-21
      DOI: 10.3390/cryst12010010
      Issue No: Vol. 12, No. 1 (2021)
       
  • Crystals, Vol. 12, Pages 11: Solution-Processable Growth and
           Characterization of Dandelion-like ZnO:B Microflower Structures

    • Authors: Selma Erat, Artur Braun, Samed Çetinkaya, Saadet Yildirimcan, Ahmet Emre Kasapoğlu, Emre Gür, Ersan Harputlu, Kasım Ocakoglu
      First page: 11
      Abstract: Intrinsic and dandelion-like microflower nano-rod structures of boron-doped ZnO thin films were synthesized with an ecofriendly and cost-effective chemical bath deposition technique from an aqueous solution of zinc nitrate hexahdyrate [Zn(NO3)2.6H2O] as a precursor solution and boric acid as a doping solution. The boron concentrations were 0.1, 0.3, 0.5, 1.0, 3.0, 5.0, and 7.0 by volume. Scanning electron micrographs showed that doping with boron appears to hinder the vertical alignment of crystallites. Additionally, independent hexagonal nano-rod structures were observed to coalesce together to form dandelion-like structures on the film’s surface. The atomic ratio of the elements was determined via the X-ray photoemission spectrum technique. There were no substantial changes in the vibration structure of the film upon doping in terms of the Raman spectra. The optical band gap of ZnO (3.28 eV) decreased with B doping. The band gap of the ZnO:B film varied between 3.18 and 3.22 eV. The activation energy of the ZnO was calculated as 0.051 eV, whereas that of the ZnO:B film containing 1.0% B was calculated as 0.013 eV at low temperatures (273–348 K), versus 0.072 eV and 0.183 eV at high temperatures (348–523 K), respectively. Consequently, it can be interpreted that the 1% B-doped ZnO, which has the lowest activation energy at both low and high temperatures, may find some application areas such as in sensors for gases and in solar cells.
      Citation: Crystals
      PubDate: 2021-12-22
      DOI: 10.3390/cryst12010011
      Issue No: Vol. 12, No. 1 (2021)
       
  • Crystals, Vol. 12, Pages 12: The Crystal Structure Elucidation of a
           Tetrapeptide Analog of Somatostatin DOTA-Phe-D-Trp-Lys-Thr-OMe

    • Authors: Sabina Diusenova, Sergey Arkhipov, Dmitry Avdeev, Pavel Dorovatovskii, Derenik Khachatryan, Vladimir Lazarenko, Michael Medvedev, Alena Nikolaeva, Mikhail Ovchinnikov, Maria Sidorova, Yan Zubavichus
      First page: 12
      Abstract: Herewith, we report for the first time the crystal structure of tetrapeptide FwKT (Phe-D-Trp-Lys-Thr), which is considered to represent an epitope for biomedically relevant hormone somatostatin. The target molecule was successfully crystalized, solved and refined as a conjugate of the tetrapeptide moiety bearing a protective group DOTA at the N-terminus and methylated at the O-terminus. The combination of a hormone active site and a powerful chelator make the substance a highly prospective targeted drug delivery system, especially for peptide receptor radionuclide therapy (PRRT) applications.
      Citation: Crystals
      PubDate: 2021-12-22
      DOI: 10.3390/cryst12010012
      Issue No: Vol. 12, No. 1 (2021)
       
  • Crystals, Vol. 12, Pages 13: Self-Localized Liquid Crystal Micro-Droplet
           Arrays on Chemically Patterned Surfaces

    • Authors: Jakub Kołacz, Qi-Huo Wei
      First page: 13
      Abstract: Liquid crystal (LC) micro-droplet arrays are elegant systems that have a range of applications, such as chemical and biological sensing, due to a sensitivity to changes in surface properties and strong optical activity. In this work, we utilize self-assembled monolayers (SAMs) to chemically micro-pattern surfaces with preferred regions for LC occupation. Exploiting discontinuous dewetting, dragging a drop of fluid over the patterned surfaces demonstrates a novel, high-yield method of confining LC in chemically defined regions. The broad applicability of this method is demonstrated by varying the size and LC phase of the droplets. Although the optical textures of the droplets are dictated by topological constraints, the additional SAM interface is shown to lock in inhomogeneous alignment. The surface effects are highly dependent on size, where larger droplets exhibit asymmetric director configurations in nematic droplets and highly knotted structures in cholesteric droplets.
      Citation: Crystals
      PubDate: 2021-12-22
      DOI: 10.3390/cryst12010013
      Issue No: Vol. 12, No. 1 (2021)
       
  • Crystals, Vol. 12, Pages 14: Development of Binder Free Interconnected 3D
           Flower of NiZn2O4 as an Advanced Electrode Materials for Supercapacitor
           Applications

    • Authors: Sajid Ali Ansari, Nazish Parveen, Mohd Al Saleh Al-Othoum, Mohammad Omaish Ansari
      First page: 14
      Abstract: The design and development of electrode materials for energy-storage applications is an area of prime focus around the globe because of the shortage of natural resources. In this study, we developed a method for preparing a novel three-dimensional binder-free pseudocapacitive NiZn2O4 active material, which was grown directly over nickel foam (NiZn2O4@3D-NF), using a simple one-step hydrothermal process. The material was characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance spectroscopy techniques were employed to evaluate the pseudocapacitive performance of the NiZn2O4 active material in a three-electrode assembly cell. The prepared NiZn2O4@3D-NF electrode exhibited an excellent specific capacitance, of 1706.25 F/g, compared to that of the NiO@3D-NF (1050 F/g) electrode because it has the bimetallic characteristics of both zinc and nickel. The NiZn2O4@3D-NF electrode showed better cyclic stability (87.5% retention) compared to the NiO@3D-NF electrode (80% retention) after 5000 cycles at a fixed current density, which also supports the durability of the NiZn2O4@3D-NF electrode. The characteristics of NiZn2O4@3D-NF include corrosion resistance, high conductivity, an abundance of active sites for electrochemical reaction, a high surface area, and synergism between the bimetallic oxides, which make it a suitable candidate for potential application in the field of energy storage.
      Citation: Crystals
      PubDate: 2021-12-22
      DOI: 10.3390/cryst12010014
      Issue No: Vol. 12, No. 1 (2021)
       
  • Crystals, Vol. 12, Pages 15: Depicting the DNA Binding and Cytotoxicity
           Studies against Human Colorectal Cancer of Aquabis
           (1-Formyl-2-Naphtholato-k2O,O′) Copper(II): A Biophysical and
           Molecular Docking Perspective

    • Authors: Ebtisam Alolayqi, Mohd Afzal, Abdullah Alarifi, Abeer Beagan, Mohd Muddassir
      First page: 15
      Abstract: In this study, we attempted to examine the biological activity of the copper(II)–based small molecule aquabis (1-formyl-2-naphtholato-k2O,O′)copper(II) (1) against colon cancer. The characterization of complex 1 was established by analytical and spectral methods in accordance with the single-crystal X-ray results. A monomeric unit of complex 1 exists in an O4 (H2O) coordination environment with slightly distorted square pyramidal geometry (τ = ~0.1). The interaction of complex 1 with calf thymus DNA (ctDNA) was determined by employing various biophysical techniques, which revealed that complex 1 binds to ctDNA at the minor groove with a binding constant of 2.38 × 105 M–1. The cytotoxicity of complex 1 towards human colorectal cell line (HCT116) was evaluated by the MTT assay, which showed an IC50 value of 11.6 μM after treatment with complex 1 for 24 h. Furthermore, the apoptotic effect induced by complex 1 was validated by DNA fragmentation pattern, which clarified that apoptosis might be regulated through the mitochondrial-mediated production of reactive oxygen species (ROS) causing DNA damage pathway. Additionally, molecular docking was also carried out to confirm the recognition of complex 1 at the minor groove.
      Citation: Crystals
      PubDate: 2021-12-22
      DOI: 10.3390/cryst12010015
      Issue No: Vol. 12, No. 1 (2021)
       
  • Crystals, Vol. 12, Pages 16: Editorial for the Special Issue on Robust
           Microelectronic Devices

    • Authors: Michael Waltl
      First page: 16
      Abstract: Integrated electronic circuits have influenced our society in recent decades and become an indispensable part of our daily lives [...]
      Citation: Crystals
      PubDate: 2021-12-23
      DOI: 10.3390/cryst12010016
      Issue No: Vol. 12, No. 1 (2021)
       
  • Crystals, Vol. 12, Pages 17: Synthesis, Structure, and Properties of
           EuLnCuSe3 (Ln = Nd, Sm, Gd, Er)

    • Authors: Oleg V. Andreev, Victor V. Atuchin, Alexander S. Aleksandrovsky, Yuriy G. Denisenko, Boris A. Zakharov, Alexander P. Tyutyunnik, Navruzbek N. Habibullayev, Dmitriy A. Velikanov, Dmitriy A. Ulybin, Daniil D. Shpindyuk
      First page: 17
      Abstract: EuLnCuSe3 (Ln = Nd, Sm, Gd, Er), due to their complex composition, should be considered new materials with the ability to purposefully change the properties. Samples of the EuLnCuSe3 were prepared using Cu, rare earth metal, Se (99.99%) by the ampoule method. The samples were obtained by the crystallization from a melt and annealed at temperatures 1073 and 1273 K. The EuErCuSe3 crystal structure was established using the single-crystal particle. EuErCuSe3 crystallizes in the orthorhombic system, space group Cmcm, KCuZrS3 structure type, with cell parameters a = 4.0555 (3), b = 13.3570 (9), and c = 10.4602 (7) Å, V = 566.62 (6) Å3. In structure EuErCuSe3, erbium ions are coordinated by selenium ions in the octahedral polyhedron, copper ions are in the tetrahedral coordination, europium ions are between copper and erbium polyhedra layers and are coordinated by selenium ions as two-cap trigonal prisms. The optical band gap is 1.79 eV. At 4.7 K, a transition from the ferrimagnetic state to the paramagnetic state was detected in EuErCuSe3. At 85 and 293 K, the compound is in a paramagnetic state. According to XRPD data, EuLnCuSe3 (Ln = Nd, Sm, Gd) compounds have a Pnma orthorhombic space group of the Eu2CuS3 structure type. For EuSmCuSe3, a = 10.75704 (15) Å, b = 4.11120 (5) Å, c = 13.37778 (22) Å. In the series of EuLnCuSe3 compounds, the optical band gap increases 1.58 eV (Nd), 1.58 eV (Sm), 1.72 eV (Gd), 1.79 eV (Er), the microhardness of the 205 (Nd), 210 (Sm), 225 (Gd) 235 ± 4 HV (Er) phases increases, and the thermal stability of the phases increases significantly. According to the measurement data of differential scanning calorimetry, the EuNdCuSe3 decomposes, according to the solid-phase reaction T = 1296 K, ΔH = 8.2 ± 0.8 kJ/mol. EuSmCuSe3 melts incongruently T = 1449 K, ΔH = 18.8 ± 1.9 kJ/mol. For the EuGdCuSe3, two (Tα↔β = 1494 K, ΔHα↔β = 14.8 kJ/mol, Tβ↔γ = 1530 K, ΔHβ↔γ = 4.8 kJ/mol) and for EuErCuSe3 three polymorphic transitions (Tα↔β = 1561 K, ΔHα↔β = 30.3 kJ/mol, Tβ↔γ = 1579 K, ΔHβ↔γ = 4.4 kJ/mol, and Tγ↔δ = 1600 K, ΔHγ↔δ = 10.1 kJ/mol). The compounds melt incongruently at the temperature of 1588 K, ΔHmelt = 17.9 ± 1.8 kJ/mol and 1664 K, ΔHmelt = 25.6 ± 2.5 kJ/mol, respectively. Incongruent melting of the phases proceeds with the formation of a solid solution of EuSe and a liquid phase.
      Citation: Crystals
      PubDate: 2021-12-23
      DOI: 10.3390/cryst12010017
      Issue No: Vol. 12, No. 1 (2021)
       
  • Crystals, Vol. 12, Pages 18: A New L-Proline Amide Hydrolase with
           Potential Application within the Amidase Process

    • Authors: Sergio Martinez-Rodríguez, Rafael Contreras-Montoya, Jesús M. Torres, Luis Álvarez de Cienfuegos, Jose Antonio Gavira
      First page: 18
      Abstract: L-proline amide hydrolase (PAH, EC 3.5.1.101) is a barely described enzyme belonging to the peptidase S33 family, and is highly similar to prolyl aminopeptidases (PAP, EC. 3.4.11.5). Besides being an S-stereoselective character towards piperidine-based carboxamides, this enzyme also hydrolyses different L-amino acid amides, turning it into a potential biocatalyst within the Amidase Process. In this work, we report the characterization of L-proline amide hydrolase from Pseudomonas syringae (PsyPAH) together with the first X-ray structure for this class of L-amino acid amidases. Recombinant PsyPAH showed optimal conditions at pH 7.0 and 35 °C, with an apparent thermal melting temperature of 46 °C. The enzyme behaved as a monomer at the optimal pH. The L-enantioselective hydrolytic activity towards different canonical and non-canonical amino-acid amides was confirmed. Structural analysis suggests key residues in the enzymatic activity.
      Citation: Crystals
      PubDate: 2021-12-23
      DOI: 10.3390/cryst12010018
      Issue No: Vol. 12, No. 1 (2021)
       
  • Crystals, Vol. 12, Pages 19: New Copper Bromide Organic-Inorganic Hybrid
           Molecular Compounds with Anionic Inorganic Core and Cationic Organic
           Ligands

    • Authors: Dawei Luo, Jian Zhang, Yu Liang, Jianling Ni, Fangming Wang, Wei Liu
      First page: 19
      Abstract: Here, organic-inorganic hybrid molecular compounds based on copper(I) bromide have been synthesized by slow-diffusion method. The inorganic modules of these two structures are Cu2Br42− anion, and the inorganic modules are coordinated to cationic organic ligands via Cu-N coordinative bonds. Both of these compounds are luminescent, emitting green emissions under UV excitation.
      Citation: Crystals
      PubDate: 2021-12-23
      DOI: 10.3390/cryst12010019
      Issue No: Vol. 12, No. 1 (2021)
       
  • Crystals, Vol. 12, Pages 20: Bulk and Single Crystal Growth Progress of
           Iron-Based Superconductors (FBS): 1111 and 1144

    • Authors: Shiv J. Singh, Mihai I. Sturza
      First page: 20
      Abstract: The discovery of iron-based superconductors (FBS) and their superconducting properties has generated huge research interest and provided a very rich physics high Tc family for fundamental and experimental studies. The 1111 (REFeAsO, RE = Rare earth) and 1144 (AEAFe4As4, AE = Ca, Eu; A = K, Rb) families are the two most important families of FBS, which offer the high Tc of 58 K and 36 K with doping and without doping, respectively. Furthermore, the crystal growth of these families is not an easy process, and a lot of efforts have been reported in this direction. However, the preparation of high-quality and suitable-sized samples is still challenging. In this short review, we will summarize the growth of materials with their superconducting properties, especially polycrystals and single crystals, for the 1111 and 1144 families, and make a short comparison between them to understand the developmental issues.
      Citation: Crystals
      PubDate: 2021-12-23
      DOI: 10.3390/cryst12010020
      Issue No: Vol. 12, No. 1 (2021)
       
  • Crystals, Vol. 12, Pages 21: Study of Phase Formation Processes in Li2ZrO3
           Ceramics Obtained by Mechanochemical Synthesis

    • Authors: Maxim V. Zdorovets, Artem L. Kozlovskiy, Baurzhan Abyshev, Talgat A. Yensepbayev, Rizahan U. Uzbekgaliyev, Dmitriy I. Shlimas
      First page: 21
      Abstract: The article is dedicated to the study of the phase formation processes in Li2ZrO3 ceramics obtained by the method of solid phase synthesis. Interest in these types of ceramics is due to their great potential for use as blanket materials in thermonuclear reactors, as well as being one of the candidates for tritium breeder materials. Analysis of the morphological features of the synthesized ceramics depending on the annealing temperature showed that the average grain size is 90–110 nm; meanwhile the degree of homogeneity is more than 90% according to electronic image data processing results. The temperature dependences of changes in the structural and conducting characteristics, as well as the phase transformation dynamics, have been established. It has been determined that a change in the phase composition by displacing the impurity LiO and ZrO2 phases results in the compaction of ceramics, as well as a decrease in their porosity. These structural changes are due to the displacement of LiO and ZrO2 impurity phases from the ceramic structure and their transformation into the Li2ZrO3 phase. During research, the following phase transformations that directly depend on the annealing temperature were established: LiO/ZrO2/Li2ZrO3 → LiO/Li2ZrO3 → Li2ZrO3. During analysis of the obtained current-voltage characteristics, depending on the annealing temperature, it was discovered that the formation of the Li2ZrO3 ordered phase in the structure results in a rise in resistance by three orders of magnitude, which indicates the dielectric nature of the ceramics.
      Citation: Crystals
      PubDate: 2021-12-24
      DOI: 10.3390/cryst12010021
      Issue No: Vol. 12, No. 1 (2021)
       
  • Crystals, Vol. 12, Pages 22: Photocatalytic Degradation of Methylene Blue
           and Metanil Yellow Dyes Using Green Synthesized Zinc Oxide (ZnO)
           Nanocrystals

    • Authors: S. Shwetha Priyadharshini, Jayachamarajapura Pranesh Shubha, Jaydev Shivalingappa, Syed Farooq Adil, Mufsir Kuniyil, Mohammad Rafe Hatshan, Baji Shaik, Kiran Kavalli
      First page: 22
      Abstract: In this work, ZnO nanocrystals (NCs) have been effectively synthesized by a simple, efficient and cost-effective method using coconut husk extract as a novel fuel. The synthesized NCs are characterized by UV-Vis, XRD, FT-IR, SEM, EDX, Raman and PL studies. The obtained ZnO were found to be UV-active with a bandgap of 2.93 eV. The X-ray diffraction pattern confirms the crystallinity of the ZnO with hexagonally structured ZnO with a crystallite size of 48 nm, while the SEM analysis reveals the hexagonal bipyramid morphology. Photocatalytic activities of the synthesized ZnO NCs are used to degrade methylene blue and metanil yellow dyes.
      Citation: Crystals
      PubDate: 2021-12-24
      DOI: 10.3390/cryst12010022
      Issue No: Vol. 12, No. 1 (2021)
       
  • Crystals, Vol. 12, Pages 23: Metallic Conduction and Carrier Localization
           in Two-Dimensional BEDO-TTF Charge-Transfer Solid Crystals

    • Authors: Hiroshi Ito, Motoki Matsuno, Seiu Katagiri, Shinji K. Yoshina, Taishi Takenobu, Manabu Ishikawa, Akihiro Otsuka, Hideki Yamochi, Yukihiro Yoshida, Gunzi Saito, Yongbing Shen, Masahiro Yamashita
      First page: 23
      Abstract: Charge-transfer salts based on bis(ethylenedioxy)tetrathiafulvalene (BEDO-TTF or BO for short) provide a stable two-dimensional (2D) metallic state, while the electrical resistance often shows an upturn at low temperatures below ~10 K. Such 2D weak carrier localization was first recognized for BO salts in the Langmuir–Blodgett films fabricated with fatty acids; however, it has not been characterized in charge-transfer solid crystals. In this paper, we discuss the carrier localization of two crystalline BO charge-transfer salts with or without magnetic ions at low temperatures through the analysis of the weak negative magnetoresistance. The phase coherence lengths deduced with temperature dependence are largely dominated by the electron–electron scattering mechanism. These results indicate that the resistivity upturn at low temperatures is caused by the 2D weak localization. Disorders causing elastic scattering within the metallic domains, such as those of terminal ethylene groups, should be suppressed to prevent the localization.
      Citation: Crystals
      PubDate: 2021-12-24
      DOI: 10.3390/cryst12010023
      Issue No: Vol. 12, No. 1 (2021)
       
  • Crystals, Vol. 12, Pages 24: Liquid Surface-Enhanced Raman Spectroscopy
           (SERS) Sensor-Based Au-Ag Colloidal Nanoparticles for Easy and Rapid
           Detection of Deltamethrin Pesticide in Brewed Tea

    • Authors: Affi Nur Hidayah, Djoko Triyono, Yuliati Herbani, Rosari Saleh
      First page: 24
      Abstract: Deltamethrin pesticides can cause inflammation, nephrotoxicity and hepatotoxicity as well as affect the activity of antioxidant enzymes in tissues. As a result of this concern, there is a rising focus on the development of fast and reliable pesticide residue testing to minimise potential risks to humans. The goal of this study is to use Au-Ag colloid nanoparticles as liquid surface-enhanced Raman spectroscopy (SERS) to improve the Raman signal in the detection of deltamethrin pesticide in a brewed tea. The liquid SERS system is fascinating to study due to its ease of use and its unlikeliness to cause several phenomena, such as photo-bleaching, combustion, sublimation and even photo-catalysis, which can interfere with the Raman signal, as shown in the SERS substrate. Our liquid SERS system is simpler than previous liquid SERS systems that have been reported. We performed the detection of pesticide analyte directly on brewed tea, without diluting it with ethanol or centrifuging it. Femtosecond laser-induced photo-reduction was employed to synthesise the liquid SERS of Au, Au-Ag, and Ag colloidal nanoparticles. The SERS was utilised to detect deltamethrin pesticide in brewed tea. The result showed that liquid SERS-based Ag NPs significantly enhance the Raman signal of pesticides compared with liquid SERS-based Au NPs and Au-Ag Nanoalloys. The maximum residue limits (MRLs) in tea in Indonesia are set at 10 ppm. Therefore, this method was also utilised to detect and improve, to 0.01 ppm, the deltamethrin pesticide Limit of Detection (LOD).
      Citation: Crystals
      PubDate: 2021-12-24
      DOI: 10.3390/cryst12010024
      Issue No: Vol. 12, No. 1 (2021)
       
  • Crystals, Vol. 12, Pages 25: Graphene Synthesis: Method, Exfoliation
           Mechanism and Large-Scale Production

    • Authors: Naixu Liu, Qingguo Tang, Bin Huang, Yaping Wang
      First page: 25
      Abstract: Graphene is a unique attractive material owing to its characteristic structure and excellent properties. To improve the preparation efficiency of graphene, reduce defects and costs, and meet the growing market demand, it is crucial to explore the improved and innovative production methods and process for graphene. This review summarizes recent advanced graphene synthesis methods including “bottom-up” and “top-down” processes, and their influence on the structure, cost, and preparation efficiency of graphene, as well as its peeling mechanism. The viability and practicality of preparing graphene using polymers peeling flake graphite or graphite filling polymer was discussed. Based on the comparative study, it is potential to mass produce graphene with large size and high quality using the viscoelasticity of polymers and their affinity to the graphite surface.
      Citation: Crystals
      PubDate: 2021-12-24
      DOI: 10.3390/cryst12010025
      Issue No: Vol. 12, No. 1 (2021)
       
  • Crystals, Vol. 12, Pages 26: Effect of Aluminum on Microstructure and
           Mechanical Properties of Weld Metal of Q960 Steel

    • Authors: Zongxuan Zou, Zhengjun Liu, Xingyu Ai, Dan Wu
      First page: 26
      Abstract: High-strength low-alloy (HSLA) steel is used in important steel structural members because of its strength and plastic toughness. Q960 steel is HSLA steel obtained by adding an appropriate amount of alloy elements and quenching and tempering treatment on the basis of ordinary low-carbon steel. This kind of steel has strong hardenability due to the alloy elements added. Cold cracks, embrittlement and softening of the heat-affected zone easily occur after welding. In particular, the low-temperature impact toughness cannot meet the requirements and limits its use. In this paper, self-shielded welding is used to adjust the content of aluminum in flux-cored wire. The relationship between weld metal (WM) microstructure and strength and properties was studied by tensile test and impact test, and the influence mechanism of Al content on weld metal microstructure and properties was analyzed. The results show that when the content of Al is 0.21%, the impact energy at 0 °C~−60 °C is the best, the tensile strength can reach 1035 MPA and the number of pores is small. The size of inclusions in WM is mostly less than 1.0 μm Al2O3 spherical oxide. It can become the center of acicular ferrite (AF) and increase the nucleation probability. However, with the increase of Al content, large irregular AlN inclusions are produced, which reduces the tensile strength and impact energy of the welded joint.
      Citation: Crystals
      PubDate: 2021-12-24
      DOI: 10.3390/cryst12010026
      Issue No: Vol. 12, No. 1 (2021)
       
  • Crystals, Vol. 12, Pages 27: Heat Transfer and Flow Characteristics of
           Pseudoplastic Nanomaterial Liquid Flowing over the Slender Cylinder with
           Variable Characteristics

    • Authors: Azad Hussain, Aysha Rehman, Naqash Ahmed, A. S. El-Shafay, Sahar A. Najati, Abdulrazak H. Almaliki, El-Sayed M. Sherif
      First page: 27
      Abstract: The present article investigates heat transfer and pseudoplastic nanomaterial liquid flow over a vertical thin cylinder. The Buongiorno model is used for this analysis. The problem gains more significance when temperature-dependent variable viscosity is taken into account. Using suitable similarity variables, nonlinear flow equations are first converted into ordinary differential equations. The generating structure is solved by the MATLAB BVP4C algorithm. Newly developed physical parameters are focused. It is observed that the heat transfer rate and the skin friction coefficient is increased remarkably because of mixing nano-particles in the base fluid by considering γb=1, 2, 3, 4 and λ=1, 1.5, 2, 2.5,3. It is found that the temperature field increases by inclining the values of thermophoresis and Brownian motion parameters. It is also evaluated that the velocity field decreases by increasing the values of the curvature parameter, Weissenberg number and buoyancy ratio characteristics.
      Citation: Crystals
      PubDate: 2021-12-24
      DOI: 10.3390/cryst12010027
      Issue No: Vol. 12, No. 1 (2021)
       
  • Crystals, Vol. 12, Pages 28: Cyclic Tension Induced Pattern Formation on
           [001] Single-Crystal Aluminum Foil

    • Authors: Kuznetsov Pavel, Khon Yury
      First page: 28
      Abstract: Cyclic tension of (100)[001]-oriented single-crystal aluminum foils with the frequency 5 Hz forms a tweed pattern. Its period is several microns and increases by a factor of 1.5 in the temperature range 233–363 K. A model is proposed for structural relaxation of the medium on spatial and time meso- and macroscales under cyclic loading. Conditions under which a steady pattern forms are found based on the analysis of kinetic equations. The number of bands in the steady pattern is found to be related to the strain rate. The process activation energy is determined.
      Citation: Crystals
      PubDate: 2021-12-24
      DOI: 10.3390/cryst12010028
      Issue No: Vol. 12, No. 1 (2021)
       
  • Crystals, Vol. 12, Pages 29: Effects of theTiB2-SiC Volume Ratio and Spark
           Plasma Sintering Temperature on the Properties and Microstructure of
           TiB2-BN-SiC Composite Ceramics

    • Authors: Shi Tian, Zelin Liao, Wenchao Guo, Qianglong He, Heng Wang, Weimin Wang
      First page: 29
      Abstract: TiB2-BN composite ceramics combine excellent electrical conductivity, thermal shock resistance, high-temperature resistance, corrosion resistance, and easy processing of TiB2 and BN. However, in practical applications, their high-temperature oxidation resistance is poor and the resistivity distribution is uneven and changes substantially with temperature. A TiB2-BN-SiC composite ceramic with stable and controllable resistivity was prepared by introducing SiC into the TiB2-BN composite ceramics. In this work, spark plasma sintering (SPS) technology was used to prepare TiB2-BN-SiC composite ceramics with various TiB2-SiC ratios and sintering temperatures. The samples were tested by XRD, SEM, and thermal and mechanical analysis. The results show that as the volume ratio of TiB2-SiC was increased from 3:1 to 12:1, the resistivity of the sample decreased from 8053.3 to 4923.3 μΩ·cm, the thermal conductivity increased from 24.89 to 34.15 W/(m k), and the thermal expansion rate increased from 7.49 (10−6/K) to 10.81 (10−6/K). As the sintering temperature was increased from 1650 to 1950 °C, the density of the sample increased, the mechanical properties were slightly improved, and the resistivity, thermal expansion rate, and thermal conductivity changed substantially. The volume ratio and sintering temperature are the key factors that control the resistivity and thermal characteristics of TiB2-SiC-BN composite ceramics, and the in situ from liquid phases of FeB and FeO also promotes the sintering of the TiB2-BN-SiC ceramics.
      Citation: Crystals
      PubDate: 2021-12-25
      DOI: 10.3390/cryst12010029
      Issue No: Vol. 12, No. 1 (2021)
       
  • Crystals, Vol. 12, Pages 30: Impact-Initiation Sensitivity of
           High-Temperature PTFE-Al-W Reactive Materials

    • Authors: Tao Sun, Yuanfeng Zheng, Ying Yuan, Haifu Wang
      First page: 30
      Abstract: Drop-weight tests were conducted to investigate the impact-initiation sensitivity of high-temperature PTFE-Al-W reactive materials. The test results show that the impact-initiation sensitivity of the materials more than doubles with increasing the sample temperature from 25 to 350 °C. Combined with the impact-induced initiation process recorded by high-speed video and the difference between reacted and unreacted residues, the crack-induced initiation mechanism was revealed. The rapid propagation of crack provides a high-temperature and aerobic environment where Al reacts violently to PTFE, which induces the initiation. Moreover, the influence of sample temperature on the sensitivity was discussed and analyzed. The analysis results indicate that the sensitivity shows a temperature interval effect, and 127 and 327 °C are the interval boundaries where the sensitivity changes significantly. The sensitivity may leaps at 127 °C and increases more rapidly in the temperature interval from 127 to 327 °C, but hardly changes after the temperature reaches 327 °C.
      Citation: Crystals
      PubDate: 2021-12-25
      DOI: 10.3390/cryst12010030
      Issue No: Vol. 12, No. 1 (2021)
       
  • Crystals, Vol. 12, Pages 31: Study of DC Magnetron Sputtered Nb Films

    • Authors: He Gao, Shijian Wang, Da Xu, Xueshen Wang, Qing Zhong, Yuan Zhong, Jinjin Li, Wenhui Cao
      First page: 31
      Abstract: As Nb films are widely used as superconducting electrodes of Josephson junctions, it is important to investigate the properties of Nb films in order to fabricate high-quality Josephson junctions. In this work, we conducted a comprehensive analysis of the relationships among the properties of DC magnetron sputtered Nb films with a constant power fabricated at the National Institute of Metrology (China). The film properties, including superconductivity, stress, lattice constant, and surface roughness, were investigated. It was found that in the case of constant power and Ar pressure, the stress and other parameters of the Nb films can maintain a relatively stable state during the continuous consumption of the target material.
      Citation: Crystals
      PubDate: 2021-12-26
      DOI: 10.3390/cryst12010031
      Issue No: Vol. 12, No. 1 (2021)
       
  • Crystals, Vol. 12, Pages 32: Evaluation of Relationship between Grain
           Morphology and Growth Temperature of HgI2 Poly-Films for Direct Conversion
           X-ray Imaging Detectors

    • Authors: Gang Xu, Ming Yao, Mingtao Zhang, Jinmeng Zhu, Yongxing Wei, Zhi Gu, Lan Zhang
      First page: 32
      Abstract: The relationship between depositing temperature and crystallinity of grain for HgI2 polycrystalline film with 170 cm2 in area deposited by Physical Vapor Deposition (PVD) was investigated, considering the matches with readout matrix pixelation for female breast examination. The different depositing temperatures, 35, 40 and 45 °C, were carried out with the same source temperature, 100 °C, corresponding to 2–2.5 h of the growth period. The films deposited were investigated by XRD, SEM, and I–V. The results show that the grain size of the films grown increases with the depositing temperature from 35 to 45 °C. At 45 °C, the polycrystalline film has a preferred microcrystal orientation with 97.2% of [001]/[hkl] and grain size is about 180–220 μm. A 256 × 256 pixels X-ray image of a bolt, key, and wiring displacement was present distinctly with 50 keV with 6 mA current of X-ray generator. Our discussions on the relationship between depositing temperature and crystallinity of grain of film suggest that the higher growth temperature, the better crystallinity and excellent preferred microcrystal orientation of grain, however, with complementary bigger grain size. For matching readout matrix pixelation, the growth period of poly-films would be reduced appropriately for reasonable grain size and preventing the crack of films deposited.
      Citation: Crystals
      PubDate: 2021-12-26
      DOI: 10.3390/cryst12010032
      Issue No: Vol. 12, No. 1 (2021)
       
  • Crystals, Vol. 12, Pages 33: Flux Growth and Properties of Volatile
           Bromine-Containing UV Nonlinear Optical Crystal K3B6O10Br

    • Authors: Huaiyu Hu, Chen Zhou, Jiahao Jiao, Siru Guo, Yanna Chen, Min Zhang
      First page: 33
      Abstract: A UV Nonlinear optical (NLO) crystal is one of the key devices in all-solid-state laser technology, and borate halides show outstanding potential due to their abundant structural diversity and short UV cut-off edges. In this article, the sizable UV NLO crystal of K3B6O10Br (KBOB) has been grown with lead-containing and lead-free fluxes systems using the high-temperature top-seeded solution growth (TSSG) method. Energy Dispersive X-ray Spectroscopy (EDS) and transmittance spectra illustrate the influence of Pb2+ ions on the transmittance properties and laser-induced damage threshold (LDT). The thermal property, namely, thermal expansion, thermal conductivity, and thermal diffusivity curves, were characterized. Moreover, a small variation of thermal refractive indexes was analyzed to illustrate the advantage of KBOB in the application for temperature-fluctuated specific regions.
      Citation: Crystals
      PubDate: 2021-12-26
      DOI: 10.3390/cryst12010033
      Issue No: Vol. 12, No. 1 (2021)
       
  • Crystals, Vol. 11, Pages 1530: Dependence of Crystallization Behavior of
           Interacting Telechelic Poly(butylene succinate) Oligomer on Molecular
           Weight

    • Authors: Cong Chen, Xue-Wen Zhang, Hai-Mu Ye
      First page: 1530
      Abstract: A large spherulite structure deteriorates the mechanical properties of crystalline polymers, and therefore various methods have been explored to increase primary nucleation density. Recently, chain-end modification has been proposed as an effective approach for regulating polymer crystal nucleation. However, the relevant nucleation mechanism still requires investigation. Therefore, in this work, 2-ureido-4[1H]-pyrimidinone (UPy) units, which can form stacks via quadruple hydrogen bonds with each other, are introduced as end groups for the preparation of interacting telechelic poly(butylene succinate) (PBS-UPy) oligomers with different molecular weights (Mns). The crystallization, especially the nucleation behavior of PBS-UPy, is studied in detail by comparing with the corresponding pre-polymer, the hydroxyl-terminal PBS (PBS-OH). The thermal properties of PBS-UPy exhibit similar Mn-dependent tendency to those of PBS-OH, but with weaker total crystallization rate. The spherulite growth rate is significantly reduced, whereas the primary nucleation density is highly promoted, after introducing UPy groups. Further investigation reveals that the mechanism of UPy stacks’ influence on nucleation ability changes from inhibition to promotion with respect to Mn. Even under an inhibition of nucleation ability, the final nucleation density is obviously increased because of a significant decline of the growth rate. In addition, the change in the impact of UPy stacks on nucleation ability is speculated to originate from the memory expression feasibility of ordered conformation in the melt during crystallization.
      Citation: Crystals
      PubDate: 2021-12-08
      DOI: 10.3390/cryst11121530
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1531: Enhanced X-ray Attenuating Efficiency of
           Silicon Dioxide Nanoparticles with Cesium Lead Bromide and
           2,5-Diphenyloxazole Co-Embedded Therein

    • Authors: Geunpyo Choe, Hyemin Kwon, Ilhwan Ryu, Sanggyu Yim
      First page: 1531
      Abstract: An X-ray-attenuation-based in vivo imaging can be a promising candidate for real-time detection of cancer in an early stage due to its significantly longer penetration depth compared to currently investigated fluorescence-emission-based imaging techniques. It has recently been demonstrated that this novel concept of imaging is feasible using cesium lead bromide (CPB) quantum dots (QDs) stably embedded in silicon dioxide (SiO2) nanoparticles (NPs). However, further improvements are necessary to realize its practical use, especially in terms of X-ray attenuation efficiency. In this study, we have found that the X-ray attenuation capability of CPB/SiO2 NPs was significantly enhanced by embedding an organic X-ray scintillator, 2,5-diphenyloxazole (PPO), together with CPB QDs in the NPs. The embedment not only solved the water dispersibility and stability problem of PPO, but also significantly increased the Hounsfield unit of the NPs, which was proportional to the degree of X-ray attenuation, by 2.7 times.
      Citation: Crystals
      PubDate: 2021-12-08
      DOI: 10.3390/cryst11121531
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1532: The Effects of Benzene on the Structure and
           Properties of Triethylamine Hydrochloride/Chloroaluminate

    • Authors: Guocai Tian, Huanhuan Du, Qingxiang Yuan
      First page: 1532
      Abstract: The effects of benzene (C6H6) on the radial distribution function, coordination number, spatial distribution function, physical and chemical properties such as density, viscosity, conductivity and transport properties of triethylamine hydrochloride /chloroaluminate ([Et3NH] Cl/AlCl3) ionic liquid were studied by first principle and molecular dynamics simulation. The stable geometry and electronic properties of benzene and ionic liquids, as well as their optimized adsorption on Cu (111) surface were obtained. The density, viscosity and conductivity obtained agreed well with the experimental values. It is found that the adsorption of cations, anions and benzene on Cu (111) surface is physical adsorption, and the adsorption capacity is [Et3NH] > C6H6 > Al2Cl7−. With the increase of benzene concentration, the density of the system decreases gradually, the interaction between cations and anions gradually weakens, resulting in the decrease of viscosity, the enhancement of diffusion and the increase of conductivity. Since the diffusion and adsorption capacity of benzene are greater than that of electroactive ion of Al2Cl7−, benzene would be easier to adsorb on the protruding part of the electrode surface, so as to reduce the effective surface area of the cathode, slow down the reduction speed of Al2Cl7− on the cathode surface and increase the over-potential, so the grain refined deposition layers can be obtained in electrodeposition.
      Citation: Crystals
      PubDate: 2021-12-08
      DOI: 10.3390/cryst11121532
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1533: Detection of Reproductive Hormones in
           Females by Using 1D Photonic Crystal-Based Simple Reconfigurable
           Biosensing Design

    • Authors: Arafa Aly, S. Awasthi, A. Mohamed, Z. Matar, M. Mohaseb, M. Al-Dossari, M. Tammam, Zaky Zaky, A. Amin, Walied Sabra
      First page: 1533
      Abstract: In this manuscript, we have explored the photonic biosensing application of the 1D photonic crystal (PhC) (AB)NCDC(AB)N, which is capable of detecting reproductive progesterone and estradiol hormones of different concentration levels in blood samples of females. The proposed structure is composed of an air cavity surrounded by two buffer layers of material MgF2, which is sandwiched between two identical 1D sub PhCs (AB)N. Both sub PhCs are made up of alternate layers of materials, SiO2 and Si, of period 5. MATLAB software has been used to obtain transmission characteristics of the structure corresponding TE wave, only with the help of the transfer matrix method. The mainstay of this research is focused on the dependence of the intensity and position of the defect mode inside the photonic bandgap with respect to reproductive hormone concentrations in blood samples, change in the thickness of the cavity region and change in angle of incidence corresponding to TE wave only. The proposed design shows high sensitivity of 98.92 nm/nmol/L and 96.58 nm/nmol/L when the cavity of a thickness of 340 nm is loaded with progesterone and estradiol hormones of concentrations of 80 nmol/L and 11 nmol/L, respectively, at an incident angle of 20°. Apart from sensitivity, other parameters such as quality factor and figure of merit have also been computed to gain deep insight about the sensing capabilities of the proposed design. These findings may pave the path for the design and development of various sensing devices capable of detecting gynecological problems pertaining to reproductive hormones in females. Thus, the simple design and excellent performance makes our design most efficient and suitable for sensing applications in industrial and biomedical fields.
      Citation: Crystals
      PubDate: 2021-12-09
      DOI: 10.3390/cryst11121533
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1534: The Role of Cations of the Precipitant in
           the Interaction of Protein Molecules in the Lysozyme Oligomers in
           Crystallization Solutions

    • Authors: Yuliya V. Kordonskaya, Vladimir I. Timofeev, Yulia A. Dyakova, Margarita A. Marchenkova, Yury V. Pisarevsky, Mikhail V. Kovalchuk
      First page: 1534
      Abstract: At the moment, the main opinion is that protein crystallization depends mainly on the the precipitant anions, therefore, there have been only few works devoted to the problem of the influence of its cations. Using the molecular dynamics method, we investigated the stability, changes in the compactness and structural transformations of lysozyme dimers and octamers in solutions with different precipitants (LiCl, NaCl, KCl and CuCl2) in order to study the contribution of cations during crystal formation in more detail. As a result, we found that cations have a rather noticeable effect on the behavior of oligomers: the higher the atomic mass of the cation, the greater the changes in the dimers structures during its dynamics and, according to the data of SAXS experiments, the lower the concentration of dimers. However, for octamers, this dependence is more complicated.
      Citation: Crystals
      PubDate: 2021-12-09
      DOI: 10.3390/cryst11121534
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1535: Crystal Structure, Microstructure and
           Electronic Properties of a Newly Discovered Ternary Phase in the Al-Cr-Sc
           System

    • Authors: Monika Kušter, Anton Meden, Boštjan Markoli, Zoran Samardžija, Maja Vončina, Pascal Boulet, Émilie Gaudry, Jean-Marie Dubois, Sašo Šturm
      First page: 1535
      Abstract: This study focused on the crystal and electronic structures of a newly discovered phase in the Al-Cr-Sc system. The latter two species do not mix in a binary alloy, but can be alloyed with aluminium in the vicinity of the Al2−xCrxSc composition, where 0.3 < x < 0.5. After preparation of the pure constituents via arc melting, high-temperature annealing at 990 °C for 240 h was required to achieve full mixing of the elements. A detailed characterisation of the crystal structure, alloy microstructure and stability was obtained using single-crystal X-ray diffraction (SCXRD) and powder X-ray diffraction (PXRD), in addition to transmission electron microscopy (TEM), especially in high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) mode, scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDXS) and differential scanning calorimetry (DSC) measurements. The crystal structure was refined to a hexagonal unit cell of the MgZn2 type, space group no. 194, P63/mmc, which belongs to the Laves phases family. Special attention was paid to the occupancy of the crystallographic sites that were filled by both Cr and Al atoms. First-principles calculations based on the density functional theory (DFT) were performed to investigate the electronic structure of this ternary phase. The total density of states (DOS) exhibited a pronounced sp character, where a shallow pseudo-gap was visible 0.5 eV below the Fermi energy that brought a small but definite contribution to the thermodynamic stability of the compound.
      Citation: Crystals
      PubDate: 2021-12-09
      DOI: 10.3390/cryst11121535
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1536: Synthesis, Spectroscopic, and Biological
           Assessments on Some New Rare Earth Metal Adrenaline Adducts

    • Authors: Sulaiman A. Al Yousef, Asma S. Al-Wasidi, Ibtisam I. S. AlZahrani, Hotoun I. Thawibaraka, Ahmed M. Naglah, Shaima A. El-Mowafi, Omar B. Ibrahim, Moamen S. Refat, Ahmed Gaber
      First page: 1536
      Abstract: Adrenaline (Adr) reacts with chlorides of Y3+, Ce3+, Nd3+ and Sm3+ in methanol at 60 °C to yield metal ion adducts of definite composition. These compounds are characterized by elemental analyses, molar conductivity, UV-Vis., 1H–NMR, Raman laser, scanning electron microscopy, energy-dispersive X-ray spectroscopy (EDX), and mid infrared spectral measurement investigations. The adducts are found to have the formulae [Y2(Adr)2(H2O)8]Cl3.8H2O, [Ce(Adr)2(H2O)2]Cl3.10H2O, [Nd(Adr)2(H2O)2]Cl3.6H2O, and [Sm(Adr)2(H2O)2]Cl3.12H2O, respectively. The two phenolic groups of the catechol moiety are linked to central metal ions based on the infrared and Raman laser spectra. The new compounds were tested against five gram-positive and two-gram negative bacteria, in addition to two Aspergillus strains. Metal adducts were shown to have stronger antibacterial and antifungal properties than free adrenaline compounds.
      Citation: Crystals
      PubDate: 2021-12-09
      DOI: 10.3390/cryst11121536
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1537: Microstructure of Ag Nano Paste Joint and
           Its Influence on Reliability

    • Authors: Dongsheng Yang, Yilong Huang, Yanhong Tian
      First page: 1537
      Abstract: In this paper, the microstructure of Ag nano paste joint was investigated in pressure-less sintering conditions, and the influence of the microstructure on the joint’s reliability was studied. Firstly, silver nanoparticles (Ag NPs) were synthesized using the redox reaction method. To tightly stack the Ag NPs in nano paste, Ag NPs with sizes of 30~50 nm and submicron-sized Ag particles were mixed. It was found that increasing the sintering temperature or sintering time can reduce the porosity of the bonding layer and the interfacial crack simultaneously, resulting in higher shear strength. When sintering at a temperature of 250 °C, a complete bonding interface was formed, with a 0.68 μm interdiffusion layer. At a higher temperature (300 °C), the bonding interface reached 1.5 μm, providing 35.9 ± 1.7 MPa of shear strength. The reliability of the die attachment was analyzed under thermal shocking from −65 °C to 150 °C for 50 cycles. As the crack could quickly grow through the interfacial defects, the separation ratio was 85% and 67% when sintered at 150 °C and 200 °C, respectively. Because of the reliable bonding interface between the die and the substrate, the Ag nano paste joint formed a slight crack on the edge of the die when sintering at 250 °C. When the joint was sintered at 300 °C, the small voids became large voids, which featured lower resistance to crack growth. Thus, instead of further improved reliability, the separation ratio increased to 37%.
      Citation: Crystals
      PubDate: 2021-12-09
      DOI: 10.3390/cryst11121537
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1538: Study on the Properties of Coated Cutters
           on Functionally Graded WC-Co/Ni-Zr Substrates with FCC Phase Enriched
           Surfaces

    • Authors: Shidi Li, Xiangyuan Xue, Jiaxing Chen, Tengxuan Lu, Zhe Zhao, Xin Deng, Zhongliang Lu, Zhongping Wang, Zhangxu Li, Zhi Qu
      First page: 1538
      Abstract: Currently, the research on mechanical behavior and cutting performance of functionally graded carbides is quite limited, which limits the rapid development of high-performance cemented carbide cutting tools. Based on WC-Co-Zr and WC-Ni-Zr, this study synthesized two kinds of cemented carbide cutters, i.e., the cemented carbide cutters with homogeneous microstructure and functionally graded carbide (FGC) cutters with FCC phase ZrN-enriched surfaces. Furthermore, TiAlN coating has been investigated on these carbide cutters. Mechanical behavior, friction, wear performance, and cutting behavior have been investigated for these coated carbides and their corresponding substrates. It was found that, as compared with coated cutters on WC-Co/Ni-Zr carbide substrates with homogeneous microstructures, the coated cutters on WC-Co/Ni-Zr FGC substrates with FCC phase-enriched surfaces show higher wear resistance and cutting life, and the wear mechanism during cutting is mainly adhesion wear.
      Citation: Crystals
      PubDate: 2021-12-09
      DOI: 10.3390/cryst11121538
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1539: Assessment of Globularity of Protein
           Structures via Minimum Volume Ellipsoids and Voxel-Based Atom
           Representation

    • Authors: Mateusz Banach
      First page: 1539
      Abstract: A computer algorithm for assessment of globularity of protein structures is presented. By enclosing the input protein in a minimum volume ellipsoid (MVEE) and calculating a profile measuring how voxelized space within this shape (cubes on a uniform grid) is occupied by atoms, it is possible to estimate how well the molecule resembles a globule. For any protein to satisfy the proposed globularity criterion, its ellipsoid profile (EP) should first confirm that atoms adequately fill the ellipsoid’s center. This property should then propagate towards the surface of the ellipsoid, although with diminishing importance. It is not required to compute the molecular surface. Globular status (full or partial) is assigned to proteins with values of their ellipsoid profiles, called here the ellipsoid indexes (EI), above certain levels. Due to structural outliers which may considerably distort the measurements, a companion method for their detection and reduction of their influence is also introduced. It is based on kernel density estimation and is shown to work well as an optional input preparation step for MVEE. Finally, the complete workflow is applied to over two thousand representatives of SCOP 2.08 domain superfamilies, surveying the landscape of tertiary structure of proteins from the Protein Data Bank.
      Citation: Crystals
      PubDate: 2021-12-09
      DOI: 10.3390/cryst11121539
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1540: Grain Boundary Wetting Phenomena in High
           Entropy Alloys Containing Nitrides, Carbides, Borides, Silicides, and
           Hydrogen: A Review

    • Authors: Boris Straumal, Eugen Rabkin, Gabriel A. Lopez, Anna Korneva, Alexei Kuzmin, Alena Gornakova, Alexander Straumal, Brigitte Baretzky
      First page: 1540
      Abstract: In this review, we analyze the structure of multicomponent alloys without principal components (they are also called high entropy alloys—HEAs), containing not only metals but also hydrogen, nitrogen, carbon, boron, or silicon. In particular, we discuss the phenomenon of grain boundary (GB) wetting by the melt or solid phase. The GB wetting can be complete or incomplete (partial). In the former case, the grains of the matrix are completely separated by the continuous layer of the second phase (solid or liquid). In the latter case of partial GB wetting, the second solid phase forms, between the matrix grains, a chain of (usually lenticular) precipitates or droplets with a non-zero value of the contact angle. To deal with the morphology of GBs, the new GB tie-lines are used, which can be constructed in the two- or multiphase areas of the multidimensional HEAs phase diagrams. The GBs in HEAs in the case of complete or partial wetting can also contain hydrides, nitrides, carbides, borides, or silicides. Thus, GB wetting by the hydrides, nitrides, carbides, borides, or silicides can be used in the so-called grain boundary chemical engineering in order to improve the properties of respective HEAs.
      Citation: Crystals
      PubDate: 2021-12-09
      DOI: 10.3390/cryst11121540
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1541: Stabilization of Long-Pitch Supertwisted
           Nematic Structures

    • Authors: Masahiro Ito, Satoshi Ohmi, Kohki Takatoh
      First page: 1541
      Abstract: Stabilized reverse twisted nematic liquid crystal devices (RTN-LCDs) were fabricated using formation of a polymer matrix under UV irradiation with an applied voltage (sustain voltage) in the vicinity of the alignment layers. In the absence of an applied voltage, the non-stabilized RTN structure gradually returns to a splay twist structure. The sustain voltage was decreased with an increase in temperature. A stabilized long-pitch supertwisted nematic (LPSTN) structure could also be formed during the RTN structure stabilization process with a much lower sustain voltage at a temperature near the clearing point. The chiral pitch for the LPSTN structure is longer than that for a typical STN structure. LPSTN-LCDs similar to RTN-LCDs show a large reduction in both the threshold and saturation voltage compared with those for TN-LCDs consisted of the same LC materials. Furthermore, a notable feature of LPSTN-LCDs is a change to a TN structure when a high voltage is applied. A black state can be realized due to the change from the LPSTN structure to the RTN structure unlike the typical STN mode under the crossed nicols condition. In contrast STN-LCDs retain their color due to the retardation because the RTN and LPSTN states are considered topologically equivalent.
      Citation: Crystals
      PubDate: 2021-12-09
      DOI: 10.3390/cryst11121541
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1542: The Fracture Behavior of 316L Stainless
           Steel with Defects Fabricated by SLM Additive Manufacturing

    • Authors: Li, Zhang
      First page: 1542
      Abstract: In this paper, the fracture behaviors of 316L stainless steel with defects fabricated by the Selective Laser Melting (SLM) additive manufacturing are studied by a peridynamic method. Firstly, the incremental formulations in the peridynamic framework are presented for the elastic-plastic problems. Then, the pairwise force of a bond for orthotropic material model is proposed according to both the local and the global coordinate systems. A simple three-step approach is developed to describe the void defects that generated in the processing of the SLM additive manufacturing in the numerical model. Next, some representative numerical examples are carried out, whose results explain the validation and accuracy of the present method, and demonstrate that the orthotropic features, micro-cracks and voids of the materials have a significant influence on the ultimate bearing capacity, crack propagation and branching of the corresponding structures. It is also revealed that the crack initiations are induced actively by the defects and the crack branching is contributed to the complex multiple-crack propagation. Finally, the achievements of this paper lay a foundation for the engineering applications of the SLM additive manufacturing materials.
      Citation: Crystals
      PubDate: 2021-12-09
      DOI: 10.3390/cryst11121542
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1543: The Application of Organic Phosphate
           Nucleating Agents in Polypropylene with Different Molecular Weights

    • Authors: Juan Li, Zhaohua Liang, Chengtao Gao, Shanshan Luo, Shaowen Huang, Daohai Zhang, Shuhao Qin
      First page: 1543
      Abstract: Two kinds of organic phosphate nucleating agent (NA-11 and NA-21) were used in PP with different molecular weights through the melt extrusion method. The dispersibility of the nucleating agents in PP, and the effect of the nucleating agents on the molecular weight, rheological behavior and crystallization behavior of PP were investigated. SEM and TEM analysis showed that the average radius of the dispersed particles (nucleating agents) was larger in LPP than that in HPP. The good dispersion of NA-21 also created more nucleation embryos for the adsorption of polypropylene molecules than the agglomerated NA-11. The gel permeation chromatography (GPC) analysis showed that the average molecular weight of HPP and LPP both decreased with the addition of a nucleating agent. The rotational rheometer and capillary rheometer analysis showed that the effect of NA-21 on reducing intermolecular entanglement was more significant, whether in HPP or LPP. The addition of NA-21 had less elastic energy storage and better flow stability, and could be processed at a higher speed. Simultaneously, the relaxation time in the blends with LPP was shorter than that with HPP. It was found that the crystallinity and nucleation efficiency of HPP/nucleating agent blends increased remarkably, while there was a barely perceptible increase in LPP/nucleating agent blends.
      Citation: Crystals
      PubDate: 2021-12-10
      DOI: 10.3390/cryst11121543
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1544: Modification of
           FA0.85MA0.15Pb(I0.85Br0.15)3 Films by NH2-POSS

    • Authors: Yangyang Zhang, Na Liu, Haipeng Xie, Jia Liu, Pan Yuan, Junhua Wei, Yuan Zhao, Baopeng Yang, Jianhua Zhang, Shitan Wang, Han Huang, Dongmei Niu, Qi Chen, Yongli Gao
      First page: 1544
      Abstract: The surface composition and morphology of FA0.85MA0.15Pb(I0.85Br0.15)3 films fabricated by the spin-coating method with different concentrations of NH2-POSS were investigated with atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), angle-resolved X-ray photoelectron spectroscopy (AR-XPS), and Fourier transform infrared spectroscopy (FTIR). It was found that the surface composition of the FA0.85MA0.15Pb(I0.85Br0.15)3 films was changed regularly through the interaction between NH2-POSS and the perovskite film. The corresponding surface morphological changes were also observed. When the concentration of NH2-POSS exceeded 10 mg/mL, a lot of cracks on the surface of the perovskite film were observed and the surface morphology was damaged. The surface composition and its distribution can be adjusted by changing the concentration of NH2-POSS and the proper concentration of NH2-POSS can substantially improve the quality of perovskite film.
      Citation: Crystals
      PubDate: 2021-12-10
      DOI: 10.3390/cryst11121544
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1545: Tuning Charge Order in (TMTTF)2X by Partial
           Anion Substitution

    • Authors: Andrej Pustogow, Daniel Dizdarevic, Sebastian Erfort, Olga Iakutkina, Valentino Merkl, Gabriele Untereiner, Martin Dressel
      First page: 1545
      Abstract: In the quasi-one-dimensional (TMTTF)2X compounds with effectively quarter-filled bands, electronic charge order is stabilized from the delicate interplay of Coulomb repulsion and electronic bandwidth. The correlation strength is commonly tuned by physical pressure or chemical substitution with stoichiometric ratios of anions and cations. Here, we investigate the charge-ordered state through partial substitution of the anions in (TMTTF)2[AsF6]1−x[SbF6]x with x≈0.3, determined from the intensity of infrared vibrations, which is sufficient to suppress the spin-Peierls state. Our dc transport experiments reveal a transition temperature TCO = 120 K and charge gap ΔCO=430 K between the values of the two parent compounds (TMTTF)2AsF6 and (TMTTF)2SbF6. Upon plotting the two parameters for different (TMTTF)2X, we find a universal relationship between TCO and ΔCO yielding that the energy gap vanishes for transition temperatures TCO≤60 K. While these quantities indicate that the macroscopic correlation strength is continuously tuned, our vibrational spectroscopy results probing the local charge disproportionation suggest that 2δ is modulated on a microscopic level.
      Citation: Crystals
      PubDate: 2021-12-10
      DOI: 10.3390/cryst11121545
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1546: Flow Analysis of Hybridized Nanomaterial
           Liquid Flow in the Existence of Multiple Slips and Hall Current Effect
           over a Slendering Stretching Surface

    • Authors: Enran Hou, Fuzhang Wang, Muhammad Naveed Khan, Shafiq Ahmad, Aysha Rehman, Abdulrazak H. Almaliki, El-Sayed M. Sherif, Ahmed M. Galal, Maram S. Alqurashi
      First page: 1546
      Abstract: Carbon nanotubes (CNTs) are favored materials in the manufacture of electrochemical devices because of their mechanical and chemical stability, good thermal and electrical conductivities, physiochemical consistency, and featherweight. With such intriguing carbon nanotubes properties in mind, the current research aims to investigate the flow of hybridized nano liquid containing MWCNTs (multi-wall carbon nanotubes) and SWCNTs (single-wall carbon nanotubes) across a slendering surface in the presence of a gyrotactic-microorganism. The temperature and solutal energy equation are modified with the impact of the modified Fourier and Fick’s law, binary chemical reaction, viscous dissipation, and joule heating. The slip conditions are imposed on the surface boundaries. The flow equations are converted into ODEs by applying similarity variables. The bvp4c approach is applied to tackle the coupled and extremely nonlinear boundary value problem. The outputs are compared with the PCM (Parametric continuation method) to ensure that the results are accurate. The influence of involved characteristics on energy distribution, velocity profiles, concentration, and microorganism field are presented graphically. It is noted that the stronger values of the wall thickness parameter and the Hartmann number produce a retardation effect; as a result, the fluid velocity declines for MWCNT and SWCNT hybrid nano liquid. Furthermore, the transport of the mass and heat rate improves with a higher amount of both the hybrid and simple nanofluids. The amount of local skin friction and the motile density of microorganisms are discussed and tabulated. Furthermore, the findings are validated by comparing them to the published literature, which is a notable feature of the present results. In this aspect, venerable stability has been accomplished.
      Citation: Crystals
      PubDate: 2021-12-10
      DOI: 10.3390/cryst11121546
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1547: Four Isostructural 3d-4f Mixed Metal
           Organic Frameworks and Their Magnetic Properties

    • Authors: Marie L. Mortensen, Abigail L. Lewis, Gregory McCandless, Kenneth J. Balkus
      First page: 1547
      Abstract: Four new isostructural 3d-4f mixed metal organic frameworks (MOFs) Cu Gd2 (BDC)4, compound 1, Cu Ho2 (BDC)4, compound 2, Cu Eu2 (BDC)4, compound 3, and Cu Dy2 (BDC)4, compound 4 were successfully synthesized. The structure, stability, and magnetic properties were analyzed. Each MOF has two lanthanide ions and one copper ion node with terephthalic acid as the organic linker. The lanthanide ions form a dimer with each having a capped trigonal prismatic geometry while the copper ion has a square planar geometry. Each of these MOFs shows varying degrees of antiferromagnetic interactions.
      Citation: Crystals
      PubDate: 2021-12-10
      DOI: 10.3390/cryst11121547
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1548: Effects of Cr Doping and Water Content on
           the Crystal Structure Transitions of Ba2In2O5

    • Authors: Raphael Finger, Marc Widenmeyer, Thomas C. Hansen, Dirk Wallacher, Stanislav Savvin, Marko Bertmer, Anke Weidenkaff, Holger Kohlmann
      First page: 1548
      Abstract: Temperature-dependent crystal structure alterations in the brownmillerite-type material Ba2In2O5 play a fundamental role in its applications: i) photocatalytic CO2 conversion; ii) oxygen transport membranes; and iii) proton conduction. This is connected to a reversible uptake of up an equimolar amount of water. In this study, in situ X-ray and neutron diffraction were combined with Raman spectroscopy and solid-state nuclear magnetic resonance experiments to unravel the effects of Cr doping and water content on the crystal structure transitions of Ba2In2O5(H2O)x over a wide temperature range (10 K ≤ T ≤ 1573 K, x < 1). A mixture of isolated and correlated protons was identified, leading to a highly dynamic situation for the protons. Hence, localisation of the protons by diffraction techniques was not possible. Cr doping led to an overall higher degree of disorder and stabilisation of the tetragonal polymorph, even at 10 K. In contrast, a further disordering at high temperatures, leading to a cubic polymorph, was found at 1123 K. Cr doping in Ba2In2O5 resulted in severe structural changes and provides a powerful way to adjust its physical properties to the respective application.
      Citation: Crystals
      PubDate: 2021-12-10
      DOI: 10.3390/cryst11121548
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1549: Influence of the Characteristics of
           Multilayer Interference Antireflection Coatings Based on Nb, Si, and Al
           Oxides on the Laser-Induced Damage Threshold of ZnGeP2 Single Crystal

    • Authors: Nikolai Nikolayevich Yudin, Mikhail Zinoviev, Vladislav Gladkiy, Evgeny Moskvichev, Igor Kinyaevsky, Sergey Podzyvalov, Elena Slyunko, Elena Zhuravleva, Anastasia Pfaf, Nikolai Aleksandrovich Yudin, Maxim Kulesh
      First page: 1549
      Abstract: In this work, the effect of the defect structure and the parameters of antireflection interference coatings based on alternating layers of Nb2O5/Al2O3 and Nb2O5/SiO2 layers on the laser-induced damage threshold of ZGP crystals under the action of Ho:YAG laser radiation at a wavelength of 2.097 μm was determined. Coating deposition was carried out using the ion-beam sputtering method. The laser-induced damage threshold of the sample with a coating based on alternating layers Nb2O5 and SiO2 was W0d = 1.8 J/cm2. The laser-induced damage threshold of the coated sample based on alternating layers of Nb2O5 and Al2O3 was W0d = 2.35 J/cm2. It has been found that the presence of silicon conglomerates in an interference antireflection coating leads to a decrease in the laser-induced damage threshold of a nonlinear crystal due to local mechanical stresses and the scattering of incident laser radiation.
      Citation: Crystals
      PubDate: 2021-12-10
      DOI: 10.3390/cryst11121549
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1550: Influence of Growth Conditions on
           Mechanical Properties of K2NiXCo(1−X) (SO4)2·6H2O Crystals

    • Authors: Natalia A. Vasilyeva, Elena B. Rudneva, Vera L. Manomenova, Marina V. Koldaeva, Alexey E. Voloshin
      First page: 1550
      Abstract: K2NiXCo(1−X) (SO4)2·6H2O (KCNSH) mixed crystal is a promising material for solar blind optical filters, combining high transparency in the ultraviolet range with effective suppression of the visible spectral region. Increasing the mechanical strength of these crystals is important to enable them to be machined in the manufacture of optical elements. A comprehensive study of the inhomogeneities and crack resistance of KCNSH crystal as a function of the growth conditions was carried out. The influence of the radial and mosaic inhomogeneity, as well as other structural defects, on the crack resistance of the crystals was analyzed. To assess the crack resistance of crystals, the parameters ca (crack length), c/a (the ratio of crack length to the size of the indentation), and KC (fracture toughness) were used. The correctness of the obtained results was analyzed. The conditions for growing KCNSH crystals with the best crack resistance were determined on the basis of the results of the study. It is shown that growing the mixed crystals using the temperature difference technique with a peripheral solution supply into the shaper provides the best crystal quality.
      Citation: Crystals
      PubDate: 2021-12-11
      DOI: 10.3390/cryst11121550
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1551: Influence of the Addition of Ni on as-Cast
           Microstructure of Duplex Fe-Mn-Al-C Lightweight Steel

    • Authors: Jaka Burja, Barbara Šetina Batič, Tilen Balaško
      First page: 1551
      Abstract: Lightweight Fe-Mn-Al-C steels have low density, and high mechanical properties, which makes them a possibility for weight reduction in vehicles for road transport. In steel production, as-cast microstructure is an important parameter for further processing. The as-cast microstructure of five lightweight duplex steels was investigated: Fe-15Mn-10Al-0.8C, Fe-15Mn-10Al-1.7Ni-0.8C, Fe-15Mn-10Al-3.9Ni-0.8C, Fe-15Mn-10Al-5.6Ni-0.8C and Fe-15Mn-10Al-8.6Ni-0.8C. The influence of Ni was analysed through thermodynamic calculations and microstructural characterization. The samples were analysed through an optical and electron microscopy. The base microstructure of the studied steel consists of ferrite and austenite. Further investigation showed that the decomposition of austenite was accompanied by the formation of kappa carbides and the B2 ordered phase. The addition of Ni prevented the formation of a lamellar kappa ferrite morphology, but at 5.6 wt.% Ni, the decomposition of austenite was most severe, resulting in a large amount of kappa carbides and a B2 ordered phase.
      Citation: Crystals
      PubDate: 2021-12-11
      DOI: 10.3390/cryst11121551
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1552: Solubility and Crystallization of Piroxicam
           from Different Solvents in Evaporative and Cooling Crystallization

    • Authors: Iben Ostergaard, Haiyan Qu
      First page: 1552
      Abstract: In this work, the solubility of a non-steroidal anti-inflammatory drug (NSAID), piroxicam, is investigated. The polymorphic form II, which is the most stable form at room temperature, was investigated in seven different solvents with various polarities. It has been found that the solubility of piroxicam in the solvents is in the following order: chloroform > dichloromethane > acetone > ethyl acetate > acetonitrile > acetic acid > methanol > hexane. Crystallization of piroxicam from different solvents has been performed with evaporative crystallization and cooling crystallization; the effects of solvent evaporation rate and solute concentration have also been studied. Both form I and form II could be produced in cooling and evaporative crystallization, and no simple link can be identified between the operating parameters and the polymorphic outcome. Results obtained in the present work showed the stochastic nature of the nucleation of different polymorphs as well as the complexity of the crystallization of a polymorphic system.
      Citation: Crystals
      PubDate: 2021-12-11
      DOI: 10.3390/cryst11121552
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1553: Snapshot Angle-Resolved Spectroscopy and
           Its Application for Study of Highly Efficient Polariton OLEDs

    • Authors: Jui-Fen Chang, Shun-Yu Hong, Yi Chen, Yan-Rong Huang, Chung-Ken Lin, Guo-Sian Ciou
      First page: 1553
      Abstract: The multifunctional snapshot angle-resolved spectroscopy (ARS) system capable of electroluminescence, photoluminescence, and reflectance measurements for thin film devices is developed based on the k-space imaging technique. Compared with the conventional goniometric ARS system, this snapshot spectroscopy system offers great advantages of rapid and simple measurement, suitable for characterizing thin film devices that are unstable or degraded under long-time or high-power driving conditions, such as OLEDs. We perform a detailed calibration of the snapshot system and show that the measured results closely match with those obtained using a goniometric system. Furthermore, we show the capabilities of the system with application in studying polariton OLEDs. The result provides comprehensive information on the polariton mode dispersion and emission distribution, and shows an effective radiative pumping of the lower polariton branch for high emission efficiency.
      Citation: Crystals
      PubDate: 2021-12-12
      DOI: 10.3390/cryst11121553
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1554: Single-Crystal Structure of HP-Sc2TeO6
           Prepared by High-Pressure/High-Temperature Synthesis

    • Authors: Raimund Ziegler, Martina Tribus, Clivia Hejny, Gunter Heymann
      First page: 1554
      Abstract: The first high-pressure scandium tellurate HP-Sc2TeO6 was synthesized from an NP-Sc2TeO6 normal-pressure precursor at 12 GPa and 1173 K using a multianvil apparatus (1000 t press, Walker-type module). The compound crystallizes in the monoclinic space group P2/c (no. 13) with a = 729.43(3), b = 512.52(2), c = 1095.02(4) pm and β = 103.88(1)°. The structure was refined from X-ray single-crystal diffractometer data: R1 = 0.0261, wR2 = 0.0344, 568 F2 values and 84 variables. HP-Sc2TeO6 is isostructural to Yb2WO6 and is built up from TeO6 octahedra, typical for tellurate(VI) compounds. During synthesis, a reconstructive transition from P321 (normal-pressure modification) to P2/c (high-pressure modification) takes place and the scandium–oxygen distances as well as the coordination number of scandium increase. However, the coordination sphere around the Te6+ cations gets only slightly distorted. High-temperature powder XRD investigations revealed a back-transformation of HP-Sc2TeO6 to the ambient-pressure modification above 973 K.
      Citation: Crystals
      PubDate: 2021-12-13
      DOI: 10.3390/cryst11121554
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1555: Negative Thermal Quenching of
           Photoluminescence from Liquid-Crystalline Molecules in Condensed Phases

    • Authors: Hussain Sami, Osama Younis, Yui Maruoka, Kenta Yamaguchi, Kumar Siddhant, Kyohei Hisano, Osamu Tsutsumi
      First page: 1555
      Abstract: The luminescence of materials in condensed phases is affected by not only their molecular structures but also their aggregated structures. In this study, we designed new liquid-crystalline luminescent materials based on biphenylacetylene with a bulky trimethylsilyl terminal group and a flexible alkoxy chain. The luminescence properties of the prepared materials were evaluated, with a particular focus on the effects of phase transitions, which cause changes in the aggregated structures. The length of the flexible chain had no effect on the luminescence in solution. However, in crystals, the luminescence spectral shape depended on the chain length because varying the chain length altered the crystal structure. Interestingly, negative thermal quenching of the luminescence from these materials was observed in condensed phases, with the isotropic phase obtained at high temperatures exhibiting a considerable increase in luminescence intensity. This thermal enhancement of the luminescence suggests that the less- or nonemissive aggregates formed in crystals are dissociated in the isotropic phase. These findings can contribute toward the development of new material design concepts for useful luminescent materials at high temperatures.
      Citation: Crystals
      PubDate: 2021-12-13
      DOI: 10.3390/cryst11121555
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1556: Effect of Nano-Si3N4 on the Mechanical
           Properties of Cement-Based Materials

    • Authors: Jianping Zhu, Lifei Zhu, Chunhua Feng, Xuemao Guan, Yujiang Sun, Wenyan Zhang
      First page: 1556
      Abstract: In this paper, in order to improve the wear resistance of road cement, nano-Si3N4 (NSN) was incorporated into cement, and the effect of NSN on compressive strength and wear resistance of road cement was investigated. The main variable of the experimental investigation was the dosage of NSN. The experimental results showed that the addition of NSN could significantly improve the compressive strength and wear resistance of cement paste. Compared with the reference group, the wear resistance can be improved by 46.5% and the compressive strength of cement paste can be improved by 12.3% when the addition of NSN is 0.16% by weight. In addition, the improvement mechanisms of NSN on cement paste were revealed by hydration heat, XRD, DTA-TG, nanoindentation, nitrogen adsorption, and SEM for microscopic phase tests. Through the microscopic analysis, the addition of NSN can accelerate the hydration reaction and promote the hydration degree, optimize the pore structure, and make the cement paste more compact. Additionally, NSN can improve the performance of the interface transition zone (ITZ) and increase the content of HD C-S-H gel. The action mechanism of NSN is mainly dominated by the surface effect, filling effect, and larger surface energy of NSN thereby improving the mechanical properties of cement-based materials. These research results have guiding significance for the design of the high wear resistance and high compressive strength of cement-based materials.
      Citation: Crystals
      PubDate: 2021-12-14
      DOI: 10.3390/cryst11121556
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1557: Shifts in Backbone Conformation of
           Acetylcholinesterases upon Binding of Covalent Inhibitors, Reversible
           Ligands and Substrates

    • Authors: Zoran Radić
      First page: 1557
      Abstract: The influence of ligand binding to human, mouse and Torpedo californica acetylcholinesterase (EC 3.1.1.7; AChE) backbone structures is analyzed in a pairwise fashion by comparison with X-ray structures of unliganded AChEs. Both complexes with reversible ligands (substrates and inhibitors) as well as covalently interacting ligands leading to the formation of covalent AChE conjugates of tetrahedral and of trigonal-planar geometries are considered. The acyl pocket loop (AP loop) in the AChE backbone is recognized as the conformationally most adaptive, but not necessarily sterically exclusive, structural element. Conformational changes of the centrally located AP loop coincide with shifts in C-terminal α-helical positions, revealing interacting components for a potential allosteric interaction within the AChE backbone. The stabilizing power of the aromatic choline binding site, with the potential to attract and pull fitting entities covalently tethered to the active Ser, is recognized. Consequently, the pull can promote catalytic reactions or relieve steric pressure within the impacted space of the AChE active center gorge. These dynamic properties of the AChE backbone inferred from the analysis of static X-ray structures contribute towards a better understanding of the molecular template important in the structure-based design of therapeutically active molecules, including AChE inhibitors as well as reactivators of conjugated, inactive AChE.
      Citation: Crystals
      PubDate: 2021-12-14
      DOI: 10.3390/cryst11121557
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1558: Reactive Crystallization Kinetics of K2SO4
           from Picromerite-Based MgSO4 and KCl

    • Authors: Abad Albis, Yecid P. Jiménez, Teófilo A. Graber, Heike Lorenz
      First page: 1558
      Abstract: In this work, the kinetic parameters, the degrees of initial supersaturation (S0) and the profiles of supersaturation (S) were determined for the reactive crystallization of K2SO4 from picromerite (K2SO4.MgSO4.6H2O) and KCl. Different reaction temperatures between 5 and 45 °C were considered, and several process analytical techniques were applied. Along with the solution temperature, the crystal chord length distribution (CLD) was continuously followed by an FBRM probe, images of nucleation and growth events as well as the crystal morphology were captured, and the absorbance of the solution was measured via ATR-FTIR spectroscopy. In addition, the ion concentrations were analyzed. It was found that S0 is inversely proportional to the reactive crystallization temperature in the K+, Mg2+/Cl−, SO42−//H2O system at 25 °C, where S0 promotes nucleation and crystal growth of K2SO4 leading to a bimodal CLD. The CLD was converted to square-weighted chord lengths for each S0 to determine the secondary nucleation rate (B), crystal growth rate (G), and suspension density (MT). By correlation, from primary nucleation rate (Bb) and G with S0, the empirical parameters b = 3.61 and g = 4.61 were obtained as the order of primary nucleation and growth, respectively. B versus G and MT were correlated to the reaction temperature providing the rate constants of B and respective activation energy, E = 69.83 kJ∙mol−1. Finally, a general Equation was derived that describes B with parameters KR = 13,810.8, i = 0.75 and j = 0.71. The K2SO4 crystals produced were of high purity, containing maximal 0.51 wt% Mg impurity, and were received with ~73% yield at 5 °C.
      Citation: Crystals
      PubDate: 2021-12-14
      DOI: 10.3390/cryst11121558
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1559: Simultaneous Detection of Relative Humidity
           and Temperature Based on Silicon On-Chip Cascaded Photonic Crystal
           Nanobeam Cavities

    • Authors: Lun Ye, Xiao Liu, Danyang Pei, Jing Peng, Shuchang Liu, Kai Guo, Xiaogang Li, Xuanyu Chen, Xuan Zhang, Daquan Yang
      First page: 1559
      Abstract: In this paper, we propose and numerically demonstrate a novel cascaded silicon-on-insulator (SOI) photonic crystal nanobeam cavity (PCNC) dual-parameter sensor for the simultaneous detection of relative humidity (RH) and temperature. The structure consists of two independent PCNCs supporting two different resonant modes: a dielectric-mode and an air-mode, respectively. The dielectric-mode nanobeam cavities (cav1) are covered with SU-8 cladding to increase the sensitivity ratio contrast between RH sensing and temperature sensing. The air-mode nanobeam cavities (cav2) are coated with a water-absorbing polyvinyl-alcohol (PVA) layer that converts the change in RH into a change in refractive index (RI) under different ambient RH levels, thereby inducing a wavelength shift. Due to the positive thermo-optic (TO) coefficient of silicon and the negative TO coefficient of SU-8 cladding, the wavelength responses take the form of a red shift for cav2 and a blue shift for cav1 as the ambient temperature increases. By using 3D finite-difference time-domain (3D-FDTD) simulations, we prove the feasibility of simultaneous sensing by monitoring a single output transmission spectrum and applying the sensor matrix. For cav1, the RH and temperature sensitivities are 0 pm/%RH and −37.9 pm/K, while those of cav2 are −389.2 pm/%RH and 58.6 pm/K. The sensitivity ratios of temperature and RH are −1.5 and 0, respectively, which is the reason for designing two different resonant modes and also implies great potential for realizing dual-parameter sensing detection. In particular, it is also noteworthy that we demonstrate the ability of the dual-parameter sensor to resist external interference by using the dual wavelength matrix method. The maximum RH and temperature detection errors caused by the deviation of resonance wavelength 1 pm are only 0.006% RH and 0.026 K, which indicates that it achieves an excellent anti-interference ability. Furthermore, the structure is very compact, occupying only 32 μm × 4 μm (length × width). Hence, the proposed sensor shows promising prospects for compact lab-on-chip integrated sensor arrays and sensing with multiple parameters.
      Citation: Crystals
      PubDate: 2021-12-14
      DOI: 10.3390/cryst11121559
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1560: Synthesis, Self-Assembly and
           Photoresponsive Behavior of Liquid Crystals Based on Azobenzene

    • Authors: Yaming Wu, Yuhai Liu, Jianxiang Chen, Runmiao Yang
      First page: 1560
      Abstract: A new amphiphilic surfactant (C4-Azo-C5-HDA) was formed by liquid crystals (LCs) based on azobenzene, whose structures were characterized by 1H-NMR spectroscopy. The reversible hydrogelation upon changes in temperature and light exposure was also studied. Under the irradiation of UV light, the trans-isomer of C4-Azo-C5-HDA rapidly photoisomerized to the cis-isomer, resulting in rapid disruption of the gel. The thermotropic liquid crystal behavior of the gelator was investigated via Differential Scanning Calorimetry (DSC) and Polarizing Optical Microscopy (POM). The biocompatibility experiment of multi-stimulus response of the liquid crystal provides a potential driving force for the development of biomaterials.
      Citation: Crystals
      PubDate: 2021-12-14
      DOI: 10.3390/cryst11121560
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1561: Suppressing Diffraction-Related Intensity
           Losses in Transmissive Single-Crystal X-ray Optics

    • Authors: Nataliya Klimova, Irina Snigireva, Anatoly Snigirev, Oleksandr Yefanov
      First page: 1561
      Abstract: The highest-quality X-ray optics can be made of single-crystal materials such as silicon, germanium, or, even better, diamond. Unfortunately, such X-ray optics have one drawback: diffraction losses or the “glitch effect”. This effect manifests itself as follows: at some energies of X-rays, the intensity of the transmitted beam drops due to the fact that some crystalline planes have satisfied the diffraction condition. Diffraction losses are usually observed in spectroscopic experiments when the energy of the X-rays changes in a certain range. However, this effect might also influence any experiment using X-rays, especially at higher energies. In this paper, we propose a method to overcome the glitch problem in transmissive optics. This is achieved using small rotations of the optical element. We describe the algorithm for “glitch-free” measurements in detail and the theory behind it.
      Citation: Crystals
      PubDate: 2021-12-14
      DOI: 10.3390/cryst11121561
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1562: The Mechanical Properties and Elastic
           Anisotropy of η′-Cu6Sn5 and Cu3Sn Intermetallic Compounds

    • Authors: Chao Ding, Jian Wang, Tianhan Liu, Hongbo Qin, Daoguo Yang, Guoqi Zhang
      First page: 1562
      Abstract: Full intermetallic compound (IMC) solder joints present fascinating advantages in high-temperature applications. In this study, the mechanical properties and elastic anisotropy of η′-Cu6Sn5 and Cu3Sn intermetallic compounds were investigated using first-principles calculations. The values of single-crystal elastic constants, the elastic (E), shear (G), and bulk (B) moduli, and Poisson’s ratio (ν) were identified. In addition, the two values of G/B and ν indicated that the two IMCs were ductile materials. The elastic anisotropy of η′-Cu6Sn5 was found to be higher than Cu3Sn by calculating the universal anisotropic index. Furthermore, an interesting discovery was that the above two types of monocrystalline IMC exhibited mechanical anisotropic behavior. Specifically, the anisotropic degree of E and B complied with the following relationship: η′-Cu6Sn5 > Cu3Sn; however, the relationship was Cu3Sn > η′-Cu6Sn5 for the G. It is noted that the anisotropic degree of E and G was similar for the two IMCs. In addition, the anisotropy of the B was higher than the G and E, respectively, for η′-Cu6Sn5; however, in the case of Cu3Sn, the anisotropic degree of B, G, and E was similar.
      Citation: Crystals
      PubDate: 2021-12-14
      DOI: 10.3390/cryst11121562
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1563: Semipolar {202̅1} GaN Edge-Emitting
           Laser Diode on Epitaxial Lateral Overgrown Wing

    • Authors: Srinivas Gandrothula, Haojun Zhang, Pavel Shapturenka, Ryan Anderson, Matthew S. Wong, Hongjian Li, Takeshi Kamikawa, Shuji Nakamura, Steven P. DenBaars
      First page: 1563
      Abstract: Edge-emitting laser diodes (LDs) were fabricated on a reduced dislocation density epitaxial lateral overgrown (ELO) wing of a semipolar {202̅1} GaN substrate, termed an ELO wing LD. Two types of facet feasibility studies were conducted: (1) “handmade” facets, wherein lifted-off ELO wing LDs were cleaved manually, and (2) facets formed on wafers through reactive ion etching (RIE). Pulsed operation electrical and optical measurements confirmed the laser action in the RIE facet LDs with a threshold current of ~19 kAcm−2 and maximum light output power of 20 mW from a single uncoated facet. Handmade facet devices showed spontaneous, LED-like emission, confirming device layers remain intact after mechanical liftoff.
      Citation: Crystals
      PubDate: 2021-12-14
      DOI: 10.3390/cryst11121563
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1564: Low-Dimensional CsPbBr3@CoBr2
           Super-Nanowire Structure for Perovskite/PMMA Composite with Highly Blue
           Emissive Performance

    • Authors: Xuan-Viet Pham, Ba-Duc Tran, Duy-Cuong Nguyen, Tu Nguyen, Minh-Vuong Nguyen, Cao-Ngoc-Hong Nguyen, Thanh-Tung Duong
      First page: 1564
      Abstract: In this study, low-dimensional CsPbBr3@CoBr2 super-nanowire (SNW) structures were synthesized via a one-pot heating strategy for highly blue emissions. By introducing CoBr2 to CsPbBr3 precursors, the shape of perovskite nanocrystals was changed from cuboids to a super-nanowire structure, as revealed through a transmission electron microscope. SNWs were formed from stacked segments of nano-plates (lateral dimension of 10–12 nm and thickness of ~2.5 nm) with lengths of several microns. The fabricated sample absorbs light at a wavelength of <450 nm, and it is emitted at a wavelength of 475 nm. It also has a radiant flux conversion efficiency of up to 85% when stimulated by a 430 nm LED light source. The average decay time of up to 80 µs indicates that they effectively prevent the recombination of electron–hole pair. The optical performance still remains over 65% when the ambient temperature is up to 120 °C compared with that under room temperature. The excellent color purity, optical quantum efficiency, long carrier lifetime, and thermal stability make CsPbBr3@CoBr2 SNWs highly promising for a range of photolumicescence applications, such as a high color rendering index lighting and transparent blue emissive screen.
      Citation: Crystals
      PubDate: 2021-12-15
      DOI: 10.3390/cryst11121564
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1565: Observation of a New Polyhalide Phase in
           Ag-Cl2 System at High Pressure

    • Authors: Adam Grzelak, Jakub Gawraczyński, Mariana Derzsi, Viktor Struzhkin, Maddury Somayazulu, Wojciech Grochala
      First page: 1565
      Abstract: In this short contribution, we examine Raman spectroscopic data from high-pressure and high-temperature experiments with an Ag-Cl2 system, and find that they are in good agreement with previously observed and calculated spectra of polychloride species. Our results imply the formation of a hitherto unknown AgClx compound, which warrants further study.
      Citation: Crystals
      PubDate: 2021-12-15
      DOI: 10.3390/cryst11121565
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1566: Influence of Anodized Titanium Surfaces on
           the Behavior of Gingival Cells in Contact with: A Systematic Review of In
           Vitro Studies

    • Authors: Marie-Joséphine Crenn, Pierre Dubot, Elie Mimran, Olivier Fromentin, Nicolas Lebon, Patrice Peyre
      First page: 1566
      Abstract: Electrochemically anodized (EA) surfaces promise enhanced biological properties and may be a solution to ensure a seal between peri-implant soft tissues and dental transmucosal components. However, the interaction between the modified nano-structured surface and the gingival cells needs further investigation. The aim of this systematic review is to analyze the biological response of gingival cells to EA titanium surfaces in in vitro studies with a score-based reliability assessment. A protocol aimed at answering the following focused question was developed: “How does the surface integrity (e.g., topography and chemistry) of EA titanium influence gingival cell response in in vitro studies'”. A search in three computer databases was performed using keywords. A quality assessment of the studies selected was performed using the SciRAP method. A total of 14 articles were selected from the 216 eligible papers. The mean reporting and the mean methodologic quality SciRAP scores were 87.7 ± 7.7/100 and 77.8 ± 7.8/100, respectively. Within the limitation of this review based on in vitro studies, it can be safely speculated that EA surfaces with optimal chemical and morphological characteristics enhance gingival fibroblast response compared to conventional titanium surfaces. When EA is combined with functionalization, it also positively influences gingival epithelial cell behavior.
      Citation: Crystals
      PubDate: 2021-12-15
      DOI: 10.3390/cryst11121566
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1567: Dosimeter Based on YAG: Ce Phosphor via
           Sol-Gel Method for Online X-ray Radiation Monitoring

    • Authors: Yuheng Yan, Changfeng Zhang, Luchuan Zheng, Taiqi Wang, Mao Li, Feiyang Xie, Qiang Guo, Gangding Peng
      First page: 1567
      Abstract: This paper focuses on the preparation of cerium-doped yttrium aluminum garnet (YAG: Ce) powder with several concentration gradients via the sol-gel method by detecting its structural characteristics via X-ray diffraction (XRD) patterns and scanning electron microscope (SEM) to verify the generation of a complete crystal phase and evenly distributed nanopowder. On this basis, the luminescence characteristics of Ce3+ are explored, the mechanism and model are discussed based on the spectra, and the ideal doping concentration was obtained by comparing the luminescence intensity along with the fluorescence quenching theory and fluorescence decay spectra of samples with different doping concentrations. Several radiation dosimeters based on YAG: Ce phosphors were made; the online radiation monitoring function was realized under the exposure of a standard X-ray source; the repeatability, accuracy, and sensitivity of the system were verified by experiments; and the factors affecting dosimeter response are discussed. This paper verifies the possibility of adhibiting YAG: Ce fluorescent powder for online X-ray monitoring, and lays the foundation for further research.
      Citation: Crystals
      PubDate: 2021-12-16
      DOI: 10.3390/cryst11121567
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1568: Physics-Based Predictive Model of
           Lack-of-Fusion Porosity in Laser Powder Bed Fusion Considering Cap Area

    • Authors: Wenjia Wang, Steven Y. Liang
      First page: 1568
      Abstract: This work proposed a computationally efficient analytical modeling strategy to calculate the product porosity in laser powder bed fusion (LPBF) induced by a lack-of-fusion defect, with the consideration of cap area in solidified molten pools, influence of powder bed characteristics on material properties, and un-melted powders in the lack-of-fusion portion. The powder packing pattern and powder bed void fraction were estimated by an advancing front method and the technique of image analysis. The effects of powder bed characteristics on the material properties were considered by analytical models with solid properties and powder bed void fraction as inputs. A physics-based thermal model was utilized to calculate the temperature distribution and molten pool size. The molten pool cross section in transvers direction was assumed to be dual half-elliptical. Based on this assumption and molten pool size, the geometry of the molten pool cross section with cap area was determined. The overlapping pattern of molten pools in adjacent scan tracks and layers was then obtained with given hatch space and layer thickness. The lack-of-fusion area fraction was obtained through image analysis of the overlapping pattern. The lack-of-fusion porosity was the multiplication of the lack-of-fusion area fraction and powder bed void fraction. The predictions of porosity under different process conditions were compared with experimental results of 316L stainless steel and showed a better predictive accuracy than the predictions that did not consider cap area. The proposed analytical modeling method has no numerical calculations, which ensures its low computational cost. Thus, the proposed model can be a convenient tool for the fast computation of lack-of-fusion-induced porosity and can help the quality control in LPBF.
      Citation: Crystals
      PubDate: 2021-12-16
      DOI: 10.3390/cryst11121568
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1569: Effect of a Continuous Annealing
           Temperature on the Microstructure, Mechanical Properties and Texture of
           Annealed Drawn and Ironed Plate

    • Authors: Zhiying Mo, Xiaohong Chu, Pengfei Gao, Dengcui Yang, Heng Cui, Yuan Fang, Haixu Li, Xiandong Yin, Zhengzhi Zhao
      First page: 1569
      Abstract: To improve the production process and produce high-quality annealed drawn and ironed (DI) plate, continuous annealing experiments were carried out at 620 °C, 640 °C, 680 °C, and 720 °C, and the effect of a continuous annealing temperature on the microstructure, mechanical characteristics, and texture of annealed DI plate were clarified. The microstructure was tested with a scanning electron microscope (SEM); the mechanical properties and weighted average of the plastic strain ratio (r¯) were measured using a tension test; and the texture characterizations were tested by X-ray powder diffractometer (XRD) and electron backscatter diffraction (EBSD). The results reveal that, with the increase of the annealing temperature, the average grain size grew from 5.14 μm to 6.56 μm, the yield strength and tensile strength decreased, and the elongation increased. The rolling textures drastically reduced after annealing. When annealed at a lower temperature of 620 °C, the texture content of {111} <110> was the highest. When the annealing temperature increased to 640 °C, 680 °C and 720 °C, the texture content of {111} <112> was higher than that of {111} <110>. The mechanical properties of the DI plate that was annealed at 640 °C are the best, with a higher r¯ value and a lower planar anisotropy value.
      Citation: Crystals
      PubDate: 2021-12-16
      DOI: 10.3390/cryst11121569
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1570: A 3D Lead Iodide Hybrid Based on a 2D
           Perovskite Subnetwork

    • Authors: Maroua Ben Haj Salah, Justine Tessier, Nicolas Mercier, Magali Allain, Antonin Leblanc, Xiaoyang Che, Claudine Katan, Mikael Kepenekian
      First page: 1570
      Abstract: Lead halide perovskites have emerged as promising materials for various optoelectronic applications. For photovoltaics, the reference compound is the 3D perovskite (MA)PbI3 (MA+ = methylammonium). However, this material suffers from instabilities towards humidity or light. This makes the search of new stable 3D lead halide materials very relevant. A strategy is the use of intermediate size cations instead of MA, which are not suitable to form the 3D ABX3 perovskites or 2D perovskites. Here, we report on a novel 3D metal halide hybrid material based on the intermediate size cation hydroxypropylammonium (HPA+), (HPA)6(MA)Pb5I17. We will see that extending the carbon chain length from two CH2 units (in the hydroxylethylammonium cation, HEA+) to three (HPA+) precludes the formation of a perovskite network as found in the lead and iodide deficient perovskite (HEA,MA)1+xPbxI3−x. In (HPA)6(MA)Pb5I17 the 3D lead halide network results from a 2D perovskite subnetworks linked by a PbI6 octahedra sharing its faces. DFT calculations confirm the direct band gap and reveal the peculiar band structure of this 3D network. On one hand the valence band has a 1D nature involving the p orbitals of the halide. On the other, the conduction band possesses a clear 2D character involving hybridization between the p orbitals of the metal and the halide.
      Citation: Crystals
      PubDate: 2021-12-16
      DOI: 10.3390/cryst11121570
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1571: Potassium Sulfate: A New Candidate to
           Explore Non-Photochemical Laser-Induced Nucleation Mechanisms

    • Authors: Mélody Briard, Clément Brandel, Sandrine Morin-Grognet, Gérard Coquerel, Valérie Dupray
      First page: 1571
      Abstract: In this paper, we report a study on the nucleation behavior of potassium sulfate (K2SO4) from aqueous solutions under the influence of unfocused nanosecond laser pulses. The objective is to contribute to the general understanding of the Non-Photochemical Laser-Induced Nucleation (NPLIN) mechanism. First, the influence of several parameters such as supersaturation as well as laser parameters (pulse energy, number of pulses, and laser polarization) on induction time, probability of nucleation and mean number of crystals in comparison with spontaneous nucleation was investigated. Then, we examined the influence of gas composition (i.e., degassing and gas bubbling (CO2 and N2)) of the supersaturated solutions on the NPLIN kinetics, showing no correlation between gas content (or nature) on the crystallization behavior. Our study questions the role of impurities within the solution regarding the mechanism of laser-induced nucleation.
      Citation: Crystals
      PubDate: 2021-12-16
      DOI: 10.3390/cryst11121571
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1572: Effect of Nutrient Solution Composition on
           Bio-Cemented Sand

    • Authors: Shihua Liang, Xueli Xiao, Zhanlin Li, Deluan Feng
      First page: 1572
      Abstract: Microbial-induced carbonate precipitation is an environmentally friendly foundation treatment technology that effectively improves soil engineering performance. The various nutrient components of liquid curing compounds significantly influence the curing effect. On the basis of penetration, dry density, water absorption, and unconfined compressive strength tests, this study showed the effect of nutrient solution composition, including urea, calcium chloride, sodium bicarbonate, ammonium chloride, and nutrient broth, on the physicomechanical properties of bio-cemented sand. The morphological differences of calcium carbonate precipitates under nutrient solution composition were compared through scanning electron microscopy (SEM). Results showed that the curing effect of compound nutrient solution was improved compared with the basic nutrient solution (urea and calcium chloride). Among the individual components added, ammonium chloride had the most remarkable effect, followed by sodium bicarbonate and nutrient broth. Among the paired components added, sodium bicarbonate + ammonium chloride had the most significant effect, followed by sodium bicarbonate + nutrient broth and ammonium chloride + nutrient broth. The strength of bio-cemented sand cured with compound nutrient solution containing five components could reach 3.43 MPa, which was 1.92 times higher than the strength of the basic nutrient solution. As shown by the SEM image, the calcium carbonate precipitation in the solidified sand was distributed in the clearance of sand particles, effectively bonding the sand particles. The calcium carbonate obtained by the composition of the compound nutrient solution precipitated the sand particles, and some of the sand particles were wrapped. Moreover, the amount of precipitation was evidently greater than that of the basic nutrient solution. Compared with the basic nutrient solution, the compound nutrient solution effectively reduced the apparent porosity and average pore size of the sand. Thus, the curing effect of the compound nutrient solution was better than that of the basic nutrient solution.
      Citation: Crystals
      PubDate: 2021-12-16
      DOI: 10.3390/cryst11121572
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1573: Joining 3YSZ Electrolyte to AISI 441
           Interconnect Using the Ag Particle Interlayer: Enhanced Mechanical and
           Aging Properties

    • Authors: Xiaoqing Si, Xiaoyang Wang, Chun Li, Tong Lin, Junlei Qi, Jian Cao
      First page: 1573
      Abstract: Reactive air brazing has been widely used in fabricating solid oxide fuel/electrolysis cell (SOFC/SOEC) stacks. However, the conventional Ag–CuO braze can lead to (I) over oxidation at the steel interconnect interface caused by its adverse reactions with the CuO and (II) many voids caused by the hydrogen-induced decomposition of CuO. The present work demonstrates that the Ag particle interlayer can be used to join yttria-stabilized zirconia (YSZ) electrolytes to AISI 441 interconnect in air instead of Ag–CuO braze. Reliable joining between YSZ and AISI 441 can be realized at 920 °C. A dense and thin oxide layer (~2 μm) is formed at the AISI 441 interface. Additionally, an interatomic joining at the YSZ/Ag interface was observed by TEM. Obtained joints displayed a shear strength of ~86.1 MPa, 161% higher than that of the joints brazed by Ag–CuO braze (~33 MPa). After aging in reducing and oxidizing atmospheres (800 °C/300 h), joints remained tight and dense, indicating a better aging performance. This technique eliminates the CuO-induced issues, which may extend lifetimes for SOFC/SOEC stacks and other ceramic/metal joining applications.
      Citation: Crystals
      PubDate: 2021-12-16
      DOI: 10.3390/cryst11121573
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1574: Theoretical Investigations of a BN
           Polymorph with sp2 + sp3 Hybridizations

    • Authors: Xinhai Yu, Riguge Su, Bei He, Binchang Ma
      First page: 1574
      Abstract: The crystal structure, mechanical anisotropy, elastic properties and electronic characteristics, as well as the stability, of P4/m BN are predicted by means of density functional theory. In this work, BN in the P4/m phase demonstrates mechanical and dynamical stability. Compared with the values of bulk B, E and G in the P4/m phase, the B of BN in the P4/m phase is greater than that of dz4 BN, while the G and E of P4/m BN are greater than those of Pnc2 BN and dz4 BN. The ratio of the bulk-to-shear modulus for P4/m BN is less than 1.75 and dz4 BN, dz2 BN and lzlz2 BN, indicating that P4/m BN is more brittle than dz4 BN, dz2 BN and lzlz2 BN. P4/m BN exhibits stronger mechanical anisotropy in G and E than Pbca BN, P42/mnm BN and Pm-3m BN but much weaker mechanical anisotropy than P4/mbm BN, B7N7, B11N11 and B15N15. In addition, P4/m BN is a quasi-direct bandgap semiconductor, and the difference between the direct and the indirect bandgap is 0.008 eV. In order to obtain further characteristics of P4/m BN for future synthetic verification, the X-ray diffraction (XRD) patterns for P4/m BN are also calculated. Given its properties, P4/m BN is a good candidate for photoelectric devices.
      Citation: Crystals
      PubDate: 2021-12-16
      DOI: 10.3390/cryst11121574
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1575: Low Temperature and High-Pressure Study of
           Bending L-Leucinium Hydrogen Maleate Crystals

    • Authors: Kseniya D. Skakunova, Denis A. Rychkov
      First page: 1575
      Abstract: The polymorphism of molecular crystals is a well-known phenomenon, resulting in modifications of physicochemical properties of solid phases. Low temperatures and high pressures are widely used to find phase transitions and quench new solid forms. In this study, L-Leucinium hydrogen maleate (LLHM), the first molecular crystal that preserves its anomalous plasticity at cryogenic temperatures, is studied at extreme conditions using Raman spectroscopy and optical microscopy. LLHM was cooled down to 11 K without any phase transition, while high pressure impact leads to perceptible changes in crystal structure in the interval of 0.0–1.35 GPa using pentane-isopentane media. Surprisingly, pressure transmitting media (PTM) play a significant role in the behavior of the LLHM system at extreme conditions—we did not find any phase change up to 3.05 GPa using paraffin as PTM. A phase transition of LLHM to amorphous form or solid–solid phase transition(s) that results in crystal fracture is reported at high pressures. LLHM stability at low temperatures suggests an alluring idea to prove LLHM preserves plasticity below 77 K.
      Citation: Crystals
      PubDate: 2021-12-16
      DOI: 10.3390/cryst11121575
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1576: Surface Acoustic Wave-Based Flexible
           Piezocomposite Strain Sensor

    • Authors: Rishikesh Srinivasaraghavan Govindarajan, Eduardo Rojas-Nastrucci, Daewon Kim
      First page: 1576
      Abstract: A surface acoustic wave (SAW), device composed of polymer and ceramic fillers, exhibiting high piezoelectricity and flexibility, has a wide range of sensing applications in the aerospace field. The demand for flexible SAW sensors has been gradually increasing due to their small size, wireless capability, low fabrication cost, and fast response time. This paper discusses the structural, thermal, and electrical properties of the developed sensor, based on different micro- and nano-fillers, such as lead zirconate titanate (PZT), calcium copper titanate (CCTO), and carbon nanotubes (CNTs), along with polyvinylidene fluoride (PVDF) as a polymer matrix. The piezocomposite substrate of the SAW sensor is fabricated using a hot press, while interdigital transducers (IDTs) are deposited through 3D printing. The piezoelectric properties are also enhanced using a non-contact corona poling technique under a high electric field to align the dipoles. Results show that the developed passive strain sensor can measure mechanical strains by examining the frequency shifts of the detected wave signals.
      Citation: Crystals
      PubDate: 2021-12-17
      DOI: 10.3390/cryst11121576
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1577: Acoustic Tunneling Study for Hexachiral
           Phononic Crystals Based on Dirac-Cone Dispersion Properties

    • Authors: Luyun Chen, Yong Liu, Hui Kong
      First page: 1577
      Abstract: Acoustic tunneling is an essential property for phononic crystals in a Dirac-cone state. By analyzing the linear dispersion relations for the accidental degeneracy of Bloch eigenstates, the influence of geometric parameters on opening the Dirac-cone state and the directional band gaps’ widths are investigated. For two-dimensional hexachiral phononic crystals, for example, the four-fold accidental degenerate Dirac point emerges at the center of the irreducible Brillouin zone (IBZ). The Dirac cone properties and the band structure inversion problem are discussed. Finally, to verify acoustic transmission properties near the double-Dirac-cone frequency region, the numerical calculation of the finite-width phononic crystal structure is carried out, and the acoustic transmission tunneling effect is proved. The results enrich and expand the manipulating method in the topological insulator problem for hexachiral phononic crystals.
      Citation: Crystals
      PubDate: 2021-12-17
      DOI: 10.3390/cryst11121577
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1578: Sensing Glucose Concentration Using
           Symmetric Metasurfaces under Oblique Incident Terahertz Waves

    • Authors: Ibraheem Al-Naib
      First page: 1578
      Abstract: In this article, a planar metamaterial sensor designed at terahertz (THz) frequencies is utilized to sense glucose concentration levels that cover hypoglycemia, normal, and hyperglycemia conditions that vary from 54 to 342 mg/dL. The sensor was developed using a symmetric complementary split rectangular resonator at an oblique incidence angle. The resonance frequency shift was used as a measure of the changes in the glucose level of the samples. The increase in the glucose concentration level exhibited clear and noticeable redshifts in the resonance frequency. For instance, a 67.5 GHz redshift has been observed for a concentration level of 54 mg/dL and increased up to 122 GHz for the 342 mg/dL concentration level. Moreover, a high sensitivity level of 75,700 nm/RIU was observed for this design. In the future, the proposed THz sensors may have potential applications in diagnosing hypocalcemia and hyperglycemia cases.
      Citation: Crystals
      PubDate: 2021-12-17
      DOI: 10.3390/cryst11121578
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1579: Case Study of High-Throughput Drug
           Screening and Remote Data Collection for SARS-CoV-2 Main Protease by Using
           Serial Femtosecond X-ray Crystallography

    • Authors: Omur Guven, Mehmet Gul, Esra Ayan, J Austin Johnson, Baris Cakilkaya, Gozde Usta, Fatma Betul Ertem, Nurettin Tokay, Busra Yuksel, Oktay Gocenler, Cengizhan Buyukdag, Sabine Botha, Gihan Ketawala, Zhen Su, Brandon Hayes, Frederic Poitevin, Alexander Batyuk, Chun Hong Yoon, Christopher Kupitz, Serdar Durdagi, Raymond G. Sierra, Hasan DeMirci
      First page: 1579
      Abstract: Since early 2020, COVID-19 has grown to affect the lives of billions globally. A worldwide investigation has been ongoing for characterizing the virus and also for finding an effective drug and developing vaccines. As time has been of the essence, a crucial part of this research has been drug repurposing; therefore, confirmation of in silico drug screening studies have been carried out for this purpose. Here we demonstrated the possibility of screening a variety of drugs efficiently by leveraging a high data collection rate of 120 images/second with the new low-noise, high dynamic range ePix10k2M Pixel Array Detector installed at the Macromolecular Femtosecond Crystallography (MFX) instrument at the Linac Coherent Light Source (LCLS). The X-ray Free-Electron Laser (XFEL) is used for remote high-throughput data collection for drug repurposing of the main protease (Mpro) of SARS-CoV-2 at ambient temperature with mitigated X-ray radiation damage. We obtained multiple structures soaked with nine drug candidate molecules in two crystal forms. Although our drug binding attempts failed, we successfully established a high-throughput Serial Femtosecond X-ray crystallographic (SFX) data collection protocol.
      Citation: Crystals
      PubDate: 2021-12-17
      DOI: 10.3390/cryst11121579
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1580: Optically Tunable and Thermally Erasable
           Terahertz Intensity Modulators Using Dye-Doped Liquid Crystal Cells with
           Metasurfaces

    • Authors: Yi-Hong Shih, Harry Miyosi Silalahi, Ting-I Tsai, Yi-Chen Chen, Jou-Yu Su, Chia-Rong Lee, Chia-Yi Huang
      First page: 1580
      Abstract: A terahertz metasurface that is imbedded into a dye-doped liquid crystal (DDLC) cell is fabricated in this work. After the metasurface-imbedded DDLC cell is irradiated with a linearly polarized pump beam, the irradiated cell is measured with a terahertz spectrometer. The irradiation of the pump beam causes the adsorption of the dye on one of the substrates of the cell, scattering incident terahertz waves and decreasing the transmittances of the terahertz metasurface at all the frequencies of its resonance spectrum. In addition, these transmittances decrease with an increase in the irradiation times of the pump beam. The adsorbed dye molecules are erased from the substrate after the cell is heated by a hot plate. The cell has similar spectra before the irradiation of the pump beam and after the heating of the hot plate. The aforementioned results reveal that the metasurface-imbedded DDLC cell is an optically tunable and thermally erasable terahertz intensity modulator. Therefore, this cell has the potential in developing intensity attenuators for terahertz imaging, frequency isolators for terahertz telecommunication, and spatial light modulators for terahertz information encryption and decryption.
      Citation: Crystals
      PubDate: 2021-12-18
      DOI: 10.3390/cryst11121580
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1581: Numerical Simulation of a Novel Method for
           PVT Growth of SiC by Adding a Graphite Block

    • Authors: Hao Luo, Xuefeng Han, Yuanchao Huang, Deren Yang, Xiaodong Pi
      First page: 1581
      Abstract: SiC crystal is an excellent substrate material for high power electronic devices and high-frequency electronic devices. Being cost-effective and defect-free are the two biggest challenges at present. For the physical vapor transport (PVT) growth of a SiC single crystal, SiC powder is used as the source material, which determines the cost and the quality of the crystal. In this paper, we propose a new design in which graphite blocks are substituted for the non-sublimated SiC powder. Temperature distribution in the SiC powder, the evolution of the SiC powder, and the vapor transport are investigated by using finite element calculations. With the addition of graphite blocks, the utilization and sublimation rate of SiC powder is higher. In addition, the reverse vapor transport above the SiC powder is eliminated. This design provides a new idea to reduce the cost of SiC crystals in industrialization.
      Citation: Crystals
      PubDate: 2021-12-18
      DOI: 10.3390/cryst11121581
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1582: Facile Synthesis Sandwich-Structured
           Ge/NrGO Nanocomposite as Anodes for High-Performance Lithium-Ion Batteries
           

    • Authors: Thanapat Autthawong, Theeraporn Promanan, Bralee Chayasombat, Ai-Shui Yu, Kohei Uosaki, Atsushi Yamaguchi, Hiroki Kurata, Torranin Chairuangsri, Thapanee Sarakonsri
      First page: 1582
      Abstract: This work aimed to design a facile preparation of sandwich-liked Ge nanoparticles/nitrogen-doped reduced graphene oxide (Ge/NrGO) nanocomposites used as anode in lithium-ion batteries through the chemical solution route. The advanced electron microscopy, STEM-HAADF and STEM-EDS mapping, evidenced that the individual Ge particles with sizes ranging from 5 to 20 nm were distributed and wrapped as sandwiches within the multi-layered NrGO sheets, which were mainly composed of the pyridinic-N form (4.8%wt.). The battery performances of the 20Ge/NrGO nanocomposite anode exhibit a high reversible capacity (700 mAh g−1) and retained its outstanding stability during long-term cycling. The internal resistance (28.0 Ω) was also decreased after cycling, according to EIS measurement. The sandwiched structure of Ge-based nanocomposite with the interconnected NrGO layers discussed in this article possessed the high-performance LIBs with great potential application in energy storage technologies.
      Citation: Crystals
      PubDate: 2021-12-19
      DOI: 10.3390/cryst11121582
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1583: Ultrathin and Optically Transparent
           Microwave Absorber Based on Flexible Silver Nanowire Film

    • Authors: Yanfei Dong, Dingwang Yu, Guochao Li, Yulin Cao, Youde Ruan, Mingtuan Lin
      First page: 1583
      Abstract: The design of an optically transparent and flexible metamaterial absorber was presented and fabricated. For this purpose, we use two different patterned silver nanowire films separated by the space layer, forming a transparent sandwiched structure with an ultrathin thickness. By analyzing the equivalent circuit model and distribution of electric field and current, the absorption physical mechanism has been theoretically investigated. The results show that the structure can achieve above 0.8 absorptions from 6 GHz to 18 GHz, and at the same time, this absorber also can obtain wide-angle property. The optical transmittance of the fabricated absorber exceeds 82% in the visible band. The results demonstrate that transparency and flexibility are the additional benefits that make the proposed absorber suitable for various potential applications.
      Citation: Crystals
      PubDate: 2021-12-19
      DOI: 10.3390/cryst11121583
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1584: Accelerated Weathering and Carbonation
           (Mild to Intensified) of Natural Canadian Silicates (Kimberlite and
           Wollastonite) for CO2 Sequestration

    • Authors: Ye Eun Chai, Salma Chalouati, Hugo Fantucci, Rafael M. Santos
      First page: 1584
      Abstract: Canada’s mineral reserves can play a very important role in curbing climate change if natural alkaline minerals are used for the process of mineral carbonation. In this work, the potential of using two Canadian natural silicates for accelerated carbonation is experimentally assessed: kimberlite mine tailing (Mg0.846Al0.165Fe0.147Ca0.067SiO3.381) from the Northwest Territories, and mined wollastonite ore (Ca0.609Mg0.132Al0.091Fe0.024SiO2.914) from Ontario. The aim of this work was to evaluate the weathering reactivity and CO2 uptake capacity via carbonation of these two comminuted rocks, both of which are made up of a mixture of alkaline minerals, under process conditions that spanned from milder to intensified. Research questions addressed include: does kimberlite contain a sufficient amount of reactive minerals to act as an effective carbon sink; is dehydroxylation necessary to activate kimberlite, and to what extent does it do this; do secondary phases of wollastonite hinder its reactivity; and can either of these minerals be carbonated without pH buffering, or only weathered' Incubator, slurry, and pressurized slurry methods of accelerated weathering and carbonation were used, and the effect of the process parameters (temperature, solid-to-liquid ration, reaction time, CO2 level, pH buffer) on the CO2 uptake and crystalline carbonates formation is tested. The reacted samples were analyzed by pH test, loss-on-ignition test, calcimeter test, and X-ray diffraction analysis. Results showed that wollastonite ore (rich in fast-weathering CaSiO3) is more suitable for accelerated carbonation than kimberlite tailing (containing slow-weathering hydrated magnesium silicates and aluminosilicates) when only its capability to rapidly form solid carbonates is considered. Incubator and pressurized buffered slurry methods proved to be most effective as under these conditions the precipitation of carbonates was more favorable, while the unbuffered slurry reaction conditions were more akin to accelerated weathering rather than accelerated carbonation.
      Citation: Crystals
      PubDate: 2021-12-19
      DOI: 10.3390/cryst11121584
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1585: Effect of Nitrate/Bromide on the Hydration
           Process of Cement Paste Mixed with Alkali Free Liquid Accelerator at Low
           Temperature

    • Authors: Yongdong Xu, Tingshu He
      First page: 1585
      Abstract: The effects of different inorganic salt accelerators (CaBr2, NaBr, Ca(NO3)2, NaNO3) and an alkali-free liquid accelerator were researched at a low temperature of 10 °C. The results showed the effects of 1.5% NaBr and 1.5% NaNO3 inorganic accelerator were pronounced. The 1-d compressive strengths of the mortar with these two inorganic salts were increased by 185.8% and 184.2%, respectively, and the final setting times were shortened from 7.74 to 6.08 min and 6.12 min, respectively. The hydration temperatures at 10 °C were measured, and the promotion effects of the inorganic accelerators were calculated: the relationship between the hydration degree was αAS + NN > αAS + NB > αAS + CB > αAS + CN > αAS. In addition, the reaction of C3A with NaBr and NaNO3 was used to analyze the products in an ettringite phase, i.e., Ca4Al2O6Br210·H2O, 3CaOAl2O3Ca(NO3)2X·H2O. The formation of these phases was detected in the hydration products of the cement paste hydration for 12 h, 24 h, and 28 d. Combined with the mass loss of the ettringite phase at 90–120 °C, determined using TG/DTG, the synergetic acceleration mechanism of the inorganic accelerators was comprehensively inferred.
      Citation: Crystals
      PubDate: 2021-12-19
      DOI: 10.3390/cryst11121585
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1586: Effect of Sodium Hydroxide, Liquid Sodium
           Silicate, Calcium Hydroxide, and Slag on the Mechanical Properties and
           Mineral Crystal Structure Evolution of Polymer Materials

    • Authors: Guodong Huang, Yaqian Li, Yuting Zhang, Jielei Zhu, Dawei Li, Bo Wang
      First page: 1586
      Abstract: To study the key factors that affect the mechanical properties of polymer materials and explore the relationship between mineral crystal formation and strength development, fly ash (FA) polymer samples were prepared using sodium hydroxide, slag, liquid sodium silicate, and hydrated lime as activators. A change in the compressive strength was observed, and X-ray diffraction measurements were carried out to confirm the change. The effects of different types and amounts of activators on the formation and transformation of mineral crystals in FA polymer samples as well as on the development of compressive strength were studied. Moreover, the relationship between the formation and transformation of mineral crystals and the development of compressive strength was established. The results show that the strongly alkaline excitation environment established by sodium hydroxide is the prerequisite for crystal formation and development of compressive strength. Under this strongly alkaline excitation environment, slag, hydrated lime, and liquid sodium silicate can increase the amounts of calcium and silicon, which promote the formation and development of hydrated calcium silicate and hydrated calcium silicoaluminate in polymers and significantly improve the compressive strength.
      Citation: Crystals
      PubDate: 2021-12-20
      DOI: 10.3390/cryst11121586
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1587: Partially Yttria-Stabilized Zirconia
           Crystals Co-Doped with Neodymium, Cerium, Terbium, Erbium or Ytterbium
           Oxides

    • Authors: Mikhail A. Borik, Alexey V. Kulebyakin, Elena E. Lomonova, Filipp O. Milovich, Valentina A. Myzina, Polina A. Ryabochkina, Natalia Y. Tabachkova, Natalia V. Sidorova, Artem S. Chislov
      First page: 1587
      Abstract: In this work, we studied the phase composition, local structure and mechanical characteristics of ZrO2 crystals partially stabilized with Y2O3 and co-doped with Nd2O3, CeO2, Er2O3, Tb2O3 and Yb2O3. Crystals were grown by directional melt crystallization in a cold container. The phase composition and structure of crystals were studied by X-ray diffractometry and transmission electron microscopy. The study of the features of the incorporation of rare-earth cations with different ionic radii into the transformable (t) and nontransformable (t’) tetragonal phases was carried out by the method of selective laser spectroscopy and time-resolved spectroscopy. Mechanical characteristics such as microhardness and fracture toughness were studied by the indentation method. It is shown that the phase composition and structure of crystals at the same total concentration of doping oxides depends on the degree of substitution of Y3+ cations by rare-earth cations. Rare earth ions of the beginning of the lanthanide series predominantly occupy positions in the nontransformable tetragonal phase of crystals based on zirconium dioxide. Ions of the end of a series of lanthanides do not show selectivity when entering the transformable (t) phase and nontransformable (t’) phase. The study of the mechanical characteristics of the crystals showed that the values of fracture toughness increase with an increase in the ionic radius of the rare earth element of the co-doped oxide, while the values of the microhardness of the crystals slightly decrease.
      Citation: Crystals
      PubDate: 2021-12-20
      DOI: 10.3390/cryst11121587
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1588: Surface-Passivated CsPbBr3 for Developing
           Efficient and Stable Perovskite Photovoltaics

    • Authors: Hyeon Ju Tak, Ji Hyeon Lee, Seunghwan Bae, Jea Woong Jo
      First page: 1588
      Abstract: All-inorganic perovskites consisting of only inorganic elements have been recently considered as highly stable semiconductors for photoactive layer of optoelectronics applications. However, the formation of high-quality thin film and trap-reduced interface has still remains an important task, which should be solved for improving the performances of all-inorganic perovskite-based photovoltaics. Here, we adopted facile method that could reduce charge-carrier recombination by depositing a passivation agent on the top surface of the CsPbBr3 all-inorganic perovskite layer. We also found that the CsPbBr3 perovskite photovoltaic prepared from surface treatment method using n-octylammonium bromide provides an improved stability in ambient environment and 1-sun illuminating condition. Therefore, the perovskite photovoltaics fabricated from our approach offered an improved power conversion efficiency of 5.44% over that of the control device without surface treatment (4.12%).
      Citation: Crystals
      PubDate: 2021-12-20
      DOI: 10.3390/cryst11121588
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1589: Synthesis, Crystal Structures, and
           Molecular Properties of Three Nitro-Substituted Chalcones

    • Authors: Alam Yair Hidalgo, Manuel Velasco, Eduardo Sánchez-Lara, Abraham Gómez-Rivera, Miguel A. Vilchis-Reyes, Cuauhtémoc Alvarado, Maribel Herrera-Ruiz, Ricardo López-Rodríguez, Nancy Romero-Ceronio, Carlos E. Lobato-García
      First page: 1589
      Abstract: Three functionalized chalcones containing combinations of nitro functional groups have been synthesized via Claisen-Schmidt condensation between 2-nitroacetophenone and nitrobenzaldehyde, and the crystal structures obtained ((E)-1,3-bis(2-nitrophenyl)prop-2-en-1-one, 1a, (E)-1-(2-nitrophenyl)-3-(3-nitrophenyl)prop-2-en-1-one, 1b and (E)-1-(2-nitrophenyl)-3-(4-nitrophenyl)prop-2-en-1-one, 1c), C15H10N2O5, are reported. Compounds 1a and 1c crystallized in the triclinic centrosymmetric space group P1¯, whereas compound 1b crystallized in the orthorhombic space group Pbca. The X-ray analysis reveals that structures 1a and 1b exhibits s-trans conformation, whereas structure 1c exists in s-cis conformation, concerning the olefinic double bonds. In addition, the results show that the position of the nitro substituent attached to the aromatic B-ring has a direct effect on the molecular coplanarity of these compounds. The Hirshfeld surface analysis suggests that the non-covalent π-π stacking interactions are the most important contributors for the crystal packing of 1a and 1b. In 1c, the crystal packing is mainly stabilized by weak intermolecular C―H···O interactions due to the planar nature of the molecule.
      Citation: Crystals
      PubDate: 2021-12-20
      DOI: 10.3390/cryst11121589
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1590: Enhanced Properties of Extended Wavelength
           InGaAs on Compositionally Undulating Step-Graded InAsP Buffers Grown by
           Molecular Beam Epitaxy

    • Authors: Xuefei Li, Jianming Xu, Tieshi Wei, Wenxian Yang, Shan Jin, Yuanyuan Wu, Shulong Lu
      First page: 1590
      Abstract: The extended wavelength InGaAs material (2.3 μm) was prepared by introducing compositionally undulating step-graded InAsyP1−y buffers with unequal layer thickness grown by solid-source molecular beam epitaxy (MBE). The properties of the extended wavelength InGaAs layer were investigated. The surface showed ordered crosshatch morphology and a low roughness of 1.38 nm. Full relaxation, steep interface and less than one threading dislocation in the InGaAs layer were demonstrated by taking advantage of the strain compensation mechanism. Room temperature photoluminescence (PL) exhibited remarkable intensity attributed to the lower density of deep non-radiative centers. The emission peak energy with varied temperatures was in good agreement with Varshni’s empirical equation, implying high crystal quality without inhomogeneity-induced localized states. Therefore, our work shows that compositionally undulating step-graded InAsP buffers with a thinner bottom modulation layer, grown by molecular beam epitaxy, is an effective approach to prepare InGaAs materials with wavelengths longer than 2.0 μm and to break the lattice limitation on the materials with even larger mismatch.
      Citation: Crystals
      PubDate: 2021-12-20
      DOI: 10.3390/cryst11121590
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1591: Iron Oxalate Humboldtine Crystallization by
           Fungus Aspergillus niger

    • Authors: Marina S. Zelenskaya, Alina R. Izatulina, Olga V. Frank-Kamenetskaya, Dmitry Y. Vlasov
      First page: 1591
      Abstract: Microfungi were able to alternate solid substrate in various environments and play a noticeable role in the formation of insoluble calcium oxalate crystals in subaerial biofilms on rock surfaces. The present work describes how iron oxalate dihydrate humboldtine is acquired under the influence of the acid-producing microscopic fungus Aspergillus niger on the surface of two iron- bearing mineral substrates in vitro. Pyrrhotite and siderite rocks, as well as the products of their alteration, were investigated using a complex of analytical methods, including powder X-ray diffraction, optical microscopy, scanning electron microscopy and EDX spectroscopy. The effect of the underlying rocks with different composition and solubility and different oxidation states of iron on Fe-oxalate crystallization and on the morphology of humboldtine crystals was shown. The mechanisms of humboldtine formation were discussed. The results obtained in vitro seem promising for using fungi in bioleaching iron and other metals from processed ores and for the development of environmentally friendly biotechnologies.
      Citation: Crystals
      PubDate: 2021-12-20
      DOI: 10.3390/cryst11121591
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1592: Thermodynamic Modeling and Mechanical
           Properties of Mg-Zn-{Y, Ce} Alloys: Review

    • Authors: Mohammad Aljarrah, Jasim Alnahas, Mohammed Alhartomi
      First page: 1592
      Abstract: Magnesium alloys are a strong candidate for various applications in automobile and aerospace industries due to their low density and specific strength. Micro-alloying magnesium with zinc, yttrium, and cerium enhances mechanical properties of magnesium through grain refinement and precipitation hardening. In this work, a critical review of magnesium-based binary systems including Mg-Zn, Mg-Y, Mg-Ce, Zn-Y, and Zn-Ce is presented. Based on the CALPHAD approach and first-principles calculations, thermodynamic modeling of Mg-Zn-Y and Mg-Zn-Ce ternary phase diagrams have been summarized. The influence of micro-alloying (yttrium and cerium) on the mechanical properties of magnesium is discussed. A comparison between mechanical properties of magnesium commercial alloys and magnesium–zinc–{yttrium and cerium} have been summarized in tables.
      Citation: Crystals
      PubDate: 2021-12-20
      DOI: 10.3390/cryst11121592
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1593: Bamboo Sawdust as a Partial Replacement of
           Cement for the Production of Sustainable Cementitious Materials

    • Authors: Yunyun Tong, Abdel-Okash Seibou, Mengya Li, Abdelhak Kaci, Jinjian Ye
      First page: 1593
      Abstract: This paper reports on the utilization of recycled moso bamboo sawdust (BS) as a substitute in a new bio-based cementitious material. In order to improve the incompatibility between biomass and cement matrix, the study firstly investigated the effect of pretreatment methods on the BS. Cold water, hot water, and alkaline solution were used. The SEM images and mechanical results showed that alkali-treated BS presented a more favorable bonding interface in the cementitious matrix, while both compressive and flexural strength were higher than for the other two treatments. Hence, the alkaline treatment method was adopted for additional studies on the effect of BS content on the microstructural, physical, rheological, and mechanical properties of composite mortar. Cement was replaced by alkali-treated BS at 1%, 3%, 5%, and 7% by mass in the mortar mixture. An increased proportion of BS led to a delayed cement setting and a reduction in workability, but a lighter and more porous structure compared to the conventional mortar. Meanwhile, the mechanical performance of composite decreased with BS content, while the compressive and flexural strength ranged between 14.1 and 37.8 MPa and 2.4 and 4.5 MPa, respectively, but still met the minimum strength requirements of masonry construction. The cement matrix incorporated 3% and 5% BS can be classified as load-bearing lightweight concrete. This result confirms that recycled BS can be a sustainable component to produce a lightweight and structural bio-based cementitious material.
      Citation: Crystals
      PubDate: 2021-12-20
      DOI: 10.3390/cryst11121593
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1594: Structural, Optical, Electrical and
           Antibacterial Properties of Fe-Doped CeO2 Nanoparticles

    • Authors: Shalendra Kumar, Suliman Yousef AlOmar, Kavita Kumari, Fadwa Albalawi, Rajesh Kumar, Faheem Ahmed, Naushad Ahmad, Sourabh Dwivedi, Parvez Ahmad Alvi
      First page: 1594
      Abstract: This paper reports the structural, optical and antimicrobial study of Ce1−xFexO2−δ (0≤ x ≤20) nanoparticles (NPs) synthesized using a microwave-assisted hydrothermal method. The XRD pattern analysed using Rietveld refinement method clearly infers that all the samples exhibit single phase nature and exclude the possibility of an impurity phase. The lattice parameters and unit cell volume were found to decrease with an increase in Fe-doping content in CeO2 nanoparticles. The crystalline size determined using XRD pattern and TEM micrographs was found to decrease with Fe doping in CeO2. Selective area electron diffraction (SAED) pattern also demonstrated the crystalline nature of the Fe-CeO2 nanoparticles. Optical properties studied using UV–vis spectroscopy indicated that band gap decreased with an increase in Fe doping. The electrical properties have been investigated via dielectric constant, dielectric loss and AC conductivity. The dielectric constant was found to increase in the Fe-doped CeO2 nanoparticles, while AC conductivity was found to be reduced, which shows good dielectric behaviour of the Fe-doped CeO2 nanoparticles. The antibacterial activity of the synthesized NPs was achieved under ambient conditions with different bacteria, and the results showed that the properties were different for both bacteria. The antimicrobial activity reflects the possibility to develop Fe-doped CeO2 NPs as antibacterial agents against extensive microorganisms to control and prevent the spread and persistence of bacterial infections.
      Citation: Crystals
      PubDate: 2021-12-20
      DOI: 10.3390/cryst11121594
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1595: Nanocrystalline Surface Layer of WO3 for
           Enhanced Proton Transport during Fuel Cell Operation

    • Authors: Xiang Song, Weiqing Guo, Yuhong Guo, Naveed Mushtaq, M. A. K. Yousaf Shah, Muhammad Sultan Irshad, Peter D. Lund, Muhammad Imran Asghar
      First page: 1595
      Abstract: High ionic conductivity in low-cost semiconductor oxides is essential to develop electrochemical energy devices for practical applications. These materials exhibit fast protonic or oxygen-ion transport in oxide materials by structural doping, but their application to solid oxide fuel cells (SOFCs) has remained a significant challenge. In this work, we have successfully synthesized nanostructured monoclinic WO3 through three steps: co-precipitation, hydrothermal, and dry freezing methods. The resulting WO3 exhibited good ionic conductivity of 6.12 × 10−2 S cm−1 and reached an excellent power density of 418 mW cm−2 at 550 °C using as an electrolyte in SOFC. To achieve such a high ionic conductivity and fuel cell performance without any doping contents was surprising, as there should not be any possibility of oxygen vacancies through the bulk structure for the ionic transport. Therefore, laterally we found that the surface layer of WO3 is reduced to oxygen-deficient when exposed to a reducing atmosphere and form WO3−δ/WO3 heterostructure, which reveals a unique ionic transport mechanism. Different microscopic and spectroscopic methods such as HR-TEM, SEM, EIS, Raman, UV-visible, XPS, and ESR spectroscopy were applied to investigate the structural, morphological, and electrochemical properties of WO3 electrolyte. The structural stability of the WO3 is explained by less dispersion between the valence and conduction bands of WO3−δ/WO3, which in turn could prevent current leakage in the fuel cell that is essential to reach high performance. This work provides some new insights for designing high-ion conducting electrolyte materials for energy storage and conversion devices.
      Citation: Crystals
      PubDate: 2021-12-20
      DOI: 10.3390/cryst11121595
      Issue No: Vol. 11, No. 12 (2021)
       
  • Crystals, Vol. 11, Pages 1596: Molecular Recognition and Shape Studies of
           3- and 4-Substituted Diarylamide Quasiracemates

    • Authors: Ali K. Brandt, Derek J. Boyle, Jacob P. Butler, Abigail R. Gillingham, Scott E. Penner, Jacqueline M. Spaniol, Alaina K. Stockdill, Morgan M. Vanderwall, Almat Yeraly, Diana R. Schepens, Kraig A. Wheeler
      First page: 1596
      Abstract: Families of quasiracemic materials constructed from 3- and 4-substituted chiral diarylamide molecular frameworks were prepared, where the imposed functional group differences systematically varied from H to CF3–9 unique components for each isomeric framework. Cocrystallization from the melt via hot stage thermomicroscopy using all possible racemic and quasiracemic combinations probed the structural boundaries of quasiracemate formation. The crystal structures and lattice energies (differential scanning calorimetry and lattice energy calculations) for many of these systems showed that quasienantiomeric components organize with near inversion symmetry and lattice energetics closely resembling those found in the racemic counterparts. This study also compared the shape space of pairs of quasienantiomers using an in silico alignment-based method to approximate the differences in molecular shape and provide a diagnostic tool for quasiracemate prediction. Comparing these results to our recent report on related 2-substituted diarylamide quasiracemates shows that functional group position can have a marked effect on quasiracemic behavior and provide critical insight to a more complete shape space, essential for defining molecular recognition processes.
      Citation: Crystals
      PubDate: 2021-12-20
      DOI: 10.3390/cryst11121596
      Issue No: Vol. 11, No. 12 (2021)
       
 
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