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 Applied Physics AJournal Prestige (SJR): 0.481 Citation Impact (citeScore): 2Number of Followers: 10      Hybrid journal (It can contain Open Access articles) ISSN (Print) 0947-8396 - ISSN (Online) 1432-0630 Published by Springer-Verlag  [2570 journals]
• Effects of alloy composition, cavity aspect ratio, and temperature of
imprinted ZrCu metallic glass films: a molecular dynamics study
• Abstract: The effects of alloy composition, cavity aspect ratio, and temperature on the pattern transfer mechanism and mechanics of ZrCu metallic glass (MG) films under a nanoimprinting process are studied using molecular dynamics simulations based on the many-body embedded-atom potential. The simulation results show that the glass transition temperature of ZrCu MGs increases with increasing Zr content. Imprinting at higher temperatures or with a higher cavity aspect ratio shortens filling time. Shear origin zones are more concentrated for imprinting at lower imprint temperatures or a higher cavity aspect ratio. The loading force increases with increasing cavity aspect ratio and decreasing Zr content. The springback ratio of a pattern increases with increasing cavity aspect ratio and decreasing Zr contare the film heights including and ent. For imprinting with a high cavity aspect ratio, the pattern width has much more springback than that of the pattern height. The sharpness of patterns significantly decreases with increasing unloading temperature.
PubDate: 2020-02-19

• Synthesis of few-layer graphene flakes by magnetically rotating arc
plasma: effects of input power and feedstock injection position
• Abstract: A magnetically rotating arc plasma system is used for the synthesis of graphene flakes by methane decomposition. Effects of input power and feedstock injection position on product microstructures are investigated. The morphology and composition of the products are characterized by transmission electron microscopy, Raman spectroscopy, X-ray diffraction, etc. Results show amorphous spherical particles with a diameter in the range of 10–40 nm and graphene flakes with 1–20 layers are generated in the plasma process. The graphene flakes are produced under a high gas temperature and long thermal history, while the spherical particles are favored by the opposite conditions. As the gas temperature increases, the products change from spherical particles to graphene flakes; moreover, the graphene flakes have larger size, fewer layers, straighter graphitic layers and better crystalline structure under a higher gas temperature. Emission spectral analysis indicates there exist lots of H atoms when the feedstock gas has a long thermal history in the plasma, revealing the importance of H atoms in the graphene flake formation. It is suggested that a high temperature and rich H environment can suppress the formation of curved or closed structures, leading to the production of graphene flakes with high crystallinity.
PubDate: 2020-02-19

• Potential of electrical discharge treatment incorporating MWCNTs to
enhance the corrosion performance of the β-titanium alloy
• Abstract: The study presents the surface modification of β-titanium alloy by the electrical discharge chemical treatment (EDCT) to achieve a corrosion-resistant surface. This technique incorporated multi-walled carbon nanotubes (MWCNTs) in the dielectric medium to alter the surface properties of the substrate. Herein, the MWCNTs act as potential candidates due to its chemical inertness and physical as well as electrical properties for achieving desired surface properties. For the sake of comparison, the μ-hydroxyapatite (μHAp) powder was also utilized in the dielectric medium. Surface morphology, topography, and elemental composition of the treated surfaces were investigated by FE-SEM, EDS, and XRD techniques, respectively. The electrochemical potentiodynamic test was carried out to investigate the corrosion resistance of untreated and treated surfaces. The treated surfaces were also evaluated in terms of change in surface morphology, wettability, and surface free energy. The outcome revealed that the alloy treated with MWCNTs favors the synthesis of the chemically stable corrosion-resistant surface. The existence of TiO2, ZrO2, Nb2O5, TaO, ZrO2, TiC2, and NbC phases detected from XRD examination affirmed that the corrosion resistance of the substrate is significantly affected by multi-walled carbon nanotube deposition. The MWCNT-treated surface presented the improved wettability and surface free energy which are twofold higher than the untreated surface. Graphic abstract
PubDate: 2020-02-19

• Synergistic effect of serpentine mineral on Li 2 B 4 O 7 glasses: optical,
structural and nuclear radiation shielding properties
• Abstract: The hypothesis of the present investigation underlined with determination of possible synergistic effects of serpentine mineral additive on Li2B4O7 glasses. A group of Li2B4O7 glasses with serpentine mineral additive were synthesized by melt-quenching technique. The elemental analysis of two different Li2B4O7 glasses with different amount of serpentine additive is tested using energy-dispersive X-ray (EDX) technique. Next, the surface morphology of synthesized serpentine glasses was investigated with scanning electron microscopy (SEM). The optical features of synthesized serpentine glasses were determined along the wavelength ranged from 200 to 900 nm. Lastly, nuclear radiation shielding properties of Li2B4O7 glasses with serpentine mineral additive were determined for gamma rays, neutrons and charged particles. MCNPX (version 2.6.0) general-purpose Monte Carlo code has been utilized for mass attenuation coefficients calculations. The results showed that the spectra are decreasing with wavelength with an observed peak centered at 450 nm. Moreover, it is observed that serpentine mineral additive improves the gamma protecting capacity of Li2B4O7 glasses. It was also noticed that the addition of serpentine mineral also enhanced the neutron and charged particle absorption of the glasses.
PubDate: 2020-02-19

• Silver sulphide nano-particles enhanced photo-current in polymer solar
cells
• Abstract: Silver sulphide nano-particles (NPs) have been employed as light trapping mechanism in the solar absorber layer of thin film inverted organic solar cell. The synthesized nano-particle has been characterized using high-resolution scanning and transmission electron microscopy (HRSEM and HRTEM), X-Ray diffraction (XRD). The effects of $$\hbox {Ag}_{2}\hbox {S}$$ NPs in the newly fabricated inverted polymer solar cell with architecture ITO/ZnO/P3HT:$$\hbox {PC}_{61}\hbox {BM}$$-$$\hbox {Ag}_{2}\hbox {S}$$ /$$\hbox {MoO}_3/\hbox {AL}$$ were characterized using optical and electrical properties of the solar absorber film. The optimized NPs in the photoactive layers are designed to improve photons harvesting, charge transport and reduced charge recombination, which resulted in the collection of high short circuit current density, as large as $$16.50\hbox { mAcm}^{-2}$$. The measured high photocurrent and better device rectification has lead to improved power conversion efficiencies (PCEs) and device stability. The best power conversion efficiency recorded in this investigations was 5.15 % at the concentration of 1 % $$\hbox {Ag}_{2}\hbox {S}$$ by weight. Furthermore, the solar cells exhibited extraordinary environmental stability stored in ambient environment which is attributed to the inverted device architecture.
PubDate: 2020-02-19

• Actively tunable terahertz electromagnetically induced transparency
analogue based on vanadium-oxide-assisted metamaterials
• Abstract: We investigate the active control of electromagnetically induced transparency (EIT) analogue based on terahertz (THz) metamaterials integrated with vanadium oxide(VO2). Due to the insulator-to-metal transition of VO2, the amplitude of EIT peak can be actively modulated with significant modulation depth. Meanwhile the group delay within the transparent window can also be dynamically tuned, bringing the active control of slow light effect. Furthermore, we also introduce independently tunable transparent peaks based on double-peak EIT, and the group delay within each transparent window can also be independently controlled. Finally, based on broadband EIT, the active tuning toward quality factor of EIT is also realized. This work introduces active EIT control with multiple degree of freedom by employing VO2, and can find potential applications in future wireless THz communication systems as multi-channel filters, switches, spacers, logic gates and modulators.
PubDate: 2020-02-17

• Chemically deposited Co 3 S 4 thin film: morphology dependant
electrocatalytic oxygen evolution reaction
• Abstract: In the field of energy conversion and storage, the cost-effective and highly active oxygen evolution reaction (OER) catalysts are in much demand. Herein, morphology dependant OER activity of Co3S4 thin film electrodes fabricated using simple and cost effective successive ionic layer adsorption and reaction (SILAR) method is demonstrated for the first time. The morphology of Co3S4 has been influenced by varying number of deposition cycles. The effect of change in morphology on the electrocatalytic properties of Co3S4 thin film electrode is studied. The OER performance of Co3S4 thin film is related to the morphology. The OER activity with an overpotential of 275 mV @10 mA cm−2 and Tafel slope of 53 mV dec−1 in 1 M KOH electrolyte is due to increased electrochemical active surface area, super-hydrophilic nature, and low electron transfer resistance of Co3S4 thin film electrode.
PubDate: 2020-02-17

• Impact of lateral straggle on linearity performance in gate-modulated (GM)
TFET
• Abstract: Tunnel field effect transistor (TFET) is considered as a more viable device than MOSFET for low power applications. However, the performance of any device depends on the accuracy of the fabrication process. At the time of fabrication, the ion implantation technique extends the source/drain region toward the channel which affects the device performance. In this paper, we have highlighted the linearity performance of gate-modulated TFET (GM-TFET) by varying the lateral straggle parameter (σ) from 0 to 6 nm. The impact of σ on higher-order harmonics (gm2 and gm3), voltage intercept point (VIP2 and VIP3), input intercept power (IIP3), intermodulation distortion (IMD3), and 1 dB compression point is investigated to study the reliability and linearity of GM TFET.
PubDate: 2020-02-17

• Hybrid nanoelectronic-magnetic device with magnetoresistive
core–shell Fe/FeC nanoparticles
• Abstract: We propose a concept of hybrid nanoelectronic-magnetic device made of magnetic Fe–C core–shell nanoparticles deposited onto prepatterned Si (111) substrate with basic circuitry made of metallic conductive lines. The synthesis of magnetic material and the creation of nanoelectronic prepatterned interdigitated die are reported and to prove the effectiveness in devices, their magnetotransport properties are investigated. Magnetic Fe/FeC nanoparticles, 11 nm diameter, with a core–shell structure have been prepared by laser pyrolysis. Two different layouts of prepatterned interdigitated die, have been conceived using e-beam lithography, with various geometries. A range of microscopy techniques, transmission electron, scanning and optical, were employed for morphological characterization of the as-obtained structures. Magnetic and magnetotransport characterization using SQUID magnetometry has been performed onto both the core–shell nanoparticles and onto the hybrid device obtained by depositing centrifugated and dispersed core–shell nanoparticles from liquid carrier solutions. From magnetotransport measurements, it has been revealed that the hybrid device made of Fe/FeC nanosized materials on prepatterned interdigitated die exhibit a large giant magnetoresistive (GMR) effect of about 8% at 300 K. This result is promising in view of the use of such devices as arrays of nanosensors and in spintronic applications.
PubDate: 2020-02-17

• Influence of low energy Ag ion irradiation for formation of Bi 2 Se 3
phase from Bi/GeSe 2 heterostructure thin films
• Abstract: The manuscript reports on the influence of 40 keV Ag –ve ion bombardment with different fluences on the microstructural and optical properties of thermally evaporated Bi/GeSe2 bilayer thin films. Two different fluences (5 × 1014 ions cm−2 and 1 × 1015 ions cm−2) of Ag –ve ions were used to irradiate the thin films that changed the microstructure and optical properties as studied by different spectroscopic methods like X-ray diffraction method (XRD), Energy dispersive X-ray spectroscopy (EDS), Field emission scanning electron microscopy (FESEM), Atomic force microscopy (AFM), Raman spectroscopy, and UV–Vis spectroscopy. The evolution of topological Bi2Se3 phase occurs after ion irradiated diffusion of Bi into GeSe2 matrix. The optical parameters as calculated from the transmission spectra infers the indirect allowed transition with reduction of Eg on ion irradiation. The various optical parameters like absorption coefficient (α), optical energy gap (Eg), Tauc parameter (B1/2), Urbach energy (Ee), extinction coefficient (k), refractive index (n) were modified with ion irradiation. The surface morphology is being changed after irradiation as probed by AFM and FESEM. The Raman spectra support the formation of Bi2Se3 phase with irradiation. The obtained results have been explained on the basis of increase in band tailing of valence band due to defect states caused by the irradiation.
PubDate: 2020-02-17

• B 2 O 3 –Bi 2 O 3 –TeO 2 –BaO and TeO 2 –Bi 2 O 3 –BaO glass
systems: a comparative assessment of gamma-ray and fast and thermal
neutron attenuation aspects
• Abstract: For Pb-free 35B2O3‒35Bi2O3‒(30–x)TeO2‒(x)BaO (x = 5, 10, 15, 20, and 25 mol%) and (90–x)TeO2‒10Bi2O3‒(x)BaO (x = 10, 15, and 20 mol%) glass systems, gamma and neutron (both fast and thermal neutron) radiation shielding features were examined and compared. Within 0.015–15 MeV photon energy, mass attenuation coefficients (μ/ρ), for all samples, which have been assessed using WinXCOM program are in fair agreement with deduced MCNP5 simulation code μ/ρ results. For all selected samples, at the lowest energy, μ/ρ has bigger values whereas at higher energy regions possess lower values. Furthermore, by employing μ/ρ values, effective atomic number (Zeff), effective electron density (Neff), half-value layer (HVL), tenth-value layer (TVL), and mean free path (MFP) are figured out for both glass systems. For studied samples, with the gradual replacement of TeO2 content with BaO, the derived values of Zeff, HVL, TVL, and MFP revealed improved γ-ray shielding potentiality. Besides, within photon energy range of 0.015–15 MeV, exposure build-up factors (EBFs) and energy absorption build-up factors (EABFs) were estimated for all samples by utilizing G‒P fitting method as a function of different penetration depths (0.5, 1, 2, 3, 4, 5, 6, 7, 8, 10, 15, 20, 25, 30, 35, and 40 mfp). The 35B2O3–35Bi2O3–5TeO2–25BaO (mol%) glass relatively larger μ/ρ and Zeff values, lower HVL, TVL, and MFP values, and minimal EBF and EABF values confirm its superior γ-ray attenuation competence among all samples. Additionally, in comparison, HVL and MFP values of 35B2O3–35Bi2O3–5TeO2–25BaO (mol%) sample are lower than the respective values of some commercial γ-ray shielding glasses and different types of standard concretes, signifying its better shielding features than them. Moreover, macroscopic removal cross-section for fast neutrons (ΣR), coherent scattering cross-section (σcs), incoherent scattering cross-section (σics), absorption cross-section (σA), and total cross-section (σT) for thermal neutrons absorption were derived for both glass systems. Among all selected glasses, 35B2O3–35Bi2O3–5TeO2–25BaO (mol%) sample possesses relatively higher ΣR (0.106 cm−1) and ‘σT’ (8.809 cm−1 at 0.0253 eV neutron energy) values for fast and thermal neutrons attenuation, respectively, demonstrating its favorable absorption capability for neutrons.
PubDate: 2020-02-17

• Microstructural, morphological behavior and removal of Cr(VI) and Se(IV)
from aqueous solutions by magnetite nanoparticles/PVA and cellulose
acetate nanofibers
• Abstract: Different contents of magnetite nanoparticles (MNPs)/graphene (G) nanosheets were incorporated into polyvinyl alcohol (PVA) and cellulose acetate (CA) electrospun nanofibers. The obtained compositions were investigated using XRD, TEM, FTIR and FESEM. The microstructural investigation displayed that nanofibers were formed with diameters around 120 nm up to 900 nm in the case of the composition at 0.1MNPs-G/PVA, while morphological features illustrated that the composition at 0.0MNPs-G/PVA fibers was formed with diameters 0.2 µm up to 0.6 µm, besides G, which was scattered through the fibers with dimensions around 17 µm. The removal efficiency of Se(IV) and Cr(VI) from aqueous solutions was evaluated and the optimum trend was obtained for the composition of 0.05MNPs-G@PVA. The high porous nanofibers may be suggested for more investigations for heavy metal removal.
PubDate: 2020-02-17

• Gamma shielding and compressive strength analyses of polyester composites
reinforced with zinc: an experiment, theoretical, and simulation based
study
• Abstract: The preparation of materials with high attenuation performance is one of the major issues in the radiation shielding applications. This study is based on the investigation of gamma-shielding performances of various polyester composites reinforced with Zn. Utilizing gamma spectrometer based on HPGe detector, the mass attenuation coefficient (μ/ρ) of the present composites was measured at various photon energies between 59.5–1408 keV. The obtained experimental data were confirmed with those of MCNPX code as well as XCOM program. It is found that the attenuation coefficient values of the studied composites are in good agreement with the results of other approaches at the investigated energies. The best photon-shielding effectiveness was observed in the composite tagged with Zn (10%). The shielding characteristics of composite enhances with the addition of Zn as filler.
PubDate: 2020-02-17

• Photoluminescence study of anatase and rutile structures of Fe-doped TiO 2
nanoparticles at different dopant concentrations
• Abstract: In this work, dependence of the surface and lattice defects of Fe-doped TiO2 at different iron concentrations and annealing temperatures was monitored by utilizing the photoluminescence (PL) spectroscopy. To achieve the maximum spectral resolution, PL spectroscopy was performed in vacuum and at different temperature of 25–300 K. It has been found that the photoluminescene properties were significantly influenced by different crystalline structure. The PL spectrum of the rutile 1% and 5% Fe:TiO2 anatase show similar PL behavior while the emission intensity of the rutile sample was lower than the anatase. This result, which can be explained by the presence of iron ions at the surface for the anatase and the increased oxygen vacancies due to the diffusion of iron into the lattice in rutile, as a result of annealing at high temperature proposes the rutile phase for the applications of environmental photocatalysis.
PubDate: 2020-02-15

• Design and fabrication of PDMS microfluidics device for rapid and
label-free DNA detection
• Abstract: Microfluidics explores the manipulation of fluid in small volume, a multidisciplinary field is imperative for DNA extraction. This study offers a simple yet substantial methodology for the fabrication of microfluidics structure-based polydimethylsiloxane (PDMS) biopolymer on a glass substrate with SU-8 photoresist for label-free detection of pathogenic genomic DNA. Two microfluidics designs for DNA detection were based on AutoCAD software, both contain two inlets and one outlet, with dimensions of 28 mm wide, and 18 mm long, and total surface area of 504 mm2. The designs were patterned in such particular sizes and dimensions to test fluid delivery and enhancement in biochemical processes in DNA extraction, while maintaining economical values as a disposable chip. Both microfluidics devices showed no leakage during fluid delivery, have heights of 97.97 and 103.44 μm, and surface roughness of 0.15 and 0.07 μm, respectively. DNA extraction from pathogenic fungus Ganoderma boninense was run on PDMS microfluidic device and UV–Vis analysis confirmed successful extraction with peaks found at 260–280 nm. Current–voltage (I–V) measurement confirmed the accuracy of microfluidic device for the specific pathogen with both real and synthetic samples of G. boninense illustrating the similar graph values of only 0.000005 A difference at 1.0 V after hybridization.
PubDate: 2020-02-15

• Surface characterization and magneto-transport study on  $$\hbox {Bi}_2\hbox {Te}_2\hbox {Se}$$Bi2Te2Se topological insulator thin film
• Abstract: Topological insulators (TIs) a new quantum state of matter predicted to have an interesting surface properties. In this report, we study the surface properties of $$\hbox {Bi}_2\hbox {Te}_2\hbox {Se}$$ (BTS) topological insulators thin films. Raman measurements on BTS thin film show a strong intensity of $$\hbox {A}{^1}_{1\text {g}}$$ ($$\sim 62\hbox { cm}{^{-1}}$$), $$\hbox {E}{^2}_\text {g}$$ ($$\sim 123\hbox { cm}{^{-1}}$$) and $$\hbox {A}{^2}_{1\text {g}}$$ ($$\sim 170\hbox { cm}{^{-1}}$$) modes in addition  to $$\hbox {A}{^2}_{1\text {u}}$$ ($$\sim 140\hbox { cm}{^{-1}}$$) modes. Elemental analyses were done using X-ray photoelectron spectroscopy (XPS). Resistance versus temperature measurement reveal a magnetic field-driven metallic behavior at high temperatures and further analysis on magnetic measurement shows a diamagnetic nature of BTS film. The magneto-resistance measurements on these films exhibit a weak antilocalization effect that arises due to quantum interfering nature of topological insulators and the measured weak anti-localization effect is fitted using Hikami–Larkin–Nagaoka (HLN) model.
PubDate: 2020-02-15

• Effect of Nb addition on the microstructure and corrosion resistance of
ferritic stainless steel
• Abstract: The effects of Nb addition on the microstructure and corrosion resistance of the as-rolled Ti-stabilized Fe-17Cr ferritic stainless steels were investigated by optical microscopy, scanning electron microscopy, X-ray diffraction, pitting tests, and electrochemical measurements. TiN precipitate tends to form in the microstructure of Ti-stabilized Fe-17Cr ferritic stainless steel. After 0.1 wt. % Nb addition, (Ti, Nb) (C, N) composite precipitates with MgO and Al2O3 core form in the microstructure. After adding 0.1 wt. % Nb, the corrosion rate of the Ti-stabilized Fe-17Cr ferritic stainless steel in FeCl3 solution is decreased significantly. The corrosion current densities decrease in HNO3, NaOH, and NaCl solutions, and the pitting corrosion potentials can be improved in NaCl solution for the Fe-17Cr ferritic stainless steel with 0.1 wt. % Nb addition.
PubDate: 2020-02-15

• Effect of synthesis method on structural and physical properties of
MgO/MgAl 2 O 4 nanocomposite as a refractory ceramic
• Abstract: This work is a comparative study of MgO/MgAl2O4 refractory nanocomposites synthesized by three different liquid phase methods. Physical–chemical and microstructural characteristics of the refractories have been characterized in terms of bulk density, apparent porosity, water adsorption capacity, crystalline phases, crystallite size, particle size distribution, morphology and composition. The mechanical behavior of the synthesized samples was evaluated in terms of bend strength and cold compressive strength. The thermal expansion coefficients of the MgO/MgAl2O4 refractories were also measured from room temperature to 1200 °C.
PubDate: 2020-02-15

• Elucidation of size, structure, surface plasmon resonance, and
photoluminescence of Ag nanoparticles synthesized by pulsed laser ablation
in distilled water and its viability as SERS substrate
• Abstract: In the present work, silver nanoparticles have been synthesized as a function of laser irradiation time and incident laser fluence by focusing a second harmonic of a Q-switched Nd:YAG laser. Increase in the irradiation time from 5 to 30 min at fixed incident laser fluence of ~ 10 J/cm2 per pulse resulted in a decrease in the average size of the nanoparticles from 20 to 15 nm, respectively. The average size of the nanoparticle was further reduced to 10 nm by increasing the incident laser fluence to ~ 22 J/cm2 at fixed irradiation time of 30 min. The reduction in the size of the nanoparticles from 20 to 15 nm induced a blue shift in the plasmonic peak from 403 to 398 nm, but with further decrease in size, a reversing of the peak towards longer wavelength was observed. The structural features of the nanoparticles exhibited dependence on both the process parameters as revealed by the X-ray diffraction, selected area electron diffraction, and high-resolution transmission electron microscope images. Longer irradiation time and higher incident fluence resulted in more oxidized phases of silver nanoparticles. These nanoparticles were found to be photoluminescent, having broad emission around the plasmonic excitation wavelength. A study on the effect of the particle size and concentration of the synthesized silver nanoparticles on its viability as surface-enhanced Raman scattering substrate for a bioactive furanoflavonoid, karanjin is reported.
PubDate: 2020-02-15

• Model for estimations of laser threshold fluencies for photothermal bubble
generation around nanoparticles
• Abstract: Theoretical investigation and estimations of the laser threshold fluencies are carried out for evaporation of water and bubble generation around of solid spherical nanoparticles by laser pulses. Simple analytical model has been developed for this purpose. The temporal dependences of nanoparticle temperature and energy conservation law are used for estimations of laser threshold fluencies. The dependences of the threshold fluencies on pulse durations, laser wavelengths, and nanoparticle radii are investigated and discussed. Comparison has been given some predicted values of the laser threshold fluencies for bubble generation in water around gold spherical nanoparticle with experimental data. The use of the fitting parameter (maximal nanoparticle temperature at the end of laser action) can provide the appropriate agreement of the results of developed model with experimental data. The estimation of maximal nanoparticle temperature can provide the analysis of realized processes under laser action on nanoparticles and necessary validation of experimental data. These model and results can be used for the estimations of the threshold fluencies for photothermal bubble generation by laser pulses around nanoparticles and for applications in various laser technologies, especially in laser nanomedicine.
PubDate: 2020-02-15

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