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  • 更新日期:2020-01-23
  • Spin effect on electronic, magnetic and optical properties of spinel CoFe2O4: A DFT study
    Mater. Sci. Eng. B (IF 3.507) Pub Date : 2020-01-22
    A. Hossain; M.S.I. Sarker; M.K.R. Khan; M.M. Rahman

    This report demonstrates the structural, electronic, magnetic, elastic, and optical properties of spinel CoFe2O4 using generalized gradient approximation (GGA). Both the spin and non-spin polarized density functional theory (DFT) have been used to study the influence of spin interactions on electronic structures, spin magnetic moments, and optical properties. The calculated magnetic moments of CoFe2O4 from spin density of states are 6.98 μB per formula unit. The Fe and Co ions prefer high spin orientations owing to the cationic polarization because of crystal field strength and intra-atomic exchange interactions, which induces large spin magnetic moments. The high values of spin magnetic moments confirm strong spin orbit coupling due to strong electron-electron interactions and can be a promising for spintronic application. Moreover, the calculated high reflectivity of CoFe2O4 material (~100%) in the Infrared-Visible-Ultraviolet region up to ~30 eV, which suggesting that the CoFe2O4 can also be a good candidate for solar reflector.

  • Enhanced flux pinning of single grain bulk (Gd, Dy)BCO superconductors processed by cold-top-seeded infiltration growth method
    Mater. Sci. Eng. B (IF 3.507) Pub Date : 2020-01-20
    Pavan Kumar Naik S; Muralidhar M; Jirsa M; Murakami M

    Single grain (Gd, Dy)BCO bulks were fabricated via cold-top-seeded infiltration growth process in air. Microstructural observations clarified that the size and dispersion of embedded (Gd, Dy)2BaCuO5 (211) secondary phase particles strongly varied in dependence of the grain refiners. The combined addition of Pt and CeO2 in each amount of 0.2 wt% increased the critical current density (Jcab, B‖c-axis) to 105 A/cm2 at 77 K and self-field. The microstructural and magnetic properties of Pt and CeO2 doped sample exhibited high homogeneity throughout the bulk sample. The optimum amount of Dy-211 is added to GdBCO along with Pt and CeO2 resulted in highest superconducting Jcab of 72 kA/cm2 at an applied magnetic field of 2.2 T with improved flux pinning which is confirmed by high values of the reduced fields (hmax = Ha/Hirr).

  • High Curie temperature in halfmetallic ferromagnets (Zn, Cr, Ti)Se and (Zn, Cr, Ti)Te for spintronic devices: Ab initio and Monte Carlo treatments
    Mater. Sci. Eng. B (IF 3.507) Pub Date : 2019-12-24
    I. Bouziani; Y. Benhouria; I. Essaoudi; A. Ainane; R. Ahuja

    The current study is purposed to investigate the magnetic- and electronic-properties of Zn1-2xCrxTixSe and Zn1-2xCrxTixTe systems by means of Ab initio and Monte Carlo calculations. We have predicted that the two systems show ferromagnetic halfmetallic behavior with 100% spin polarization at the Fermi level and their ferromagnetic stability is attributed to the double exchange coupling. Our calculations suggest further that these compounds exhibit a 2nd order ferromagnetic transition with high Curie temperature. Thus, (Zn, Cr, Ti)Se and (Zn, Cr, Ti)Te compounds are strong candidates for spintronic devices, especially for magnetic random access memories (MRAM) based on the spin transfer torque.

  • 更新日期:2019-12-25
  • Surface, structural and cryogenic magnetic studies of Cu, Co substituted NiFe2O4 thin films grown on Si substrate
    Mater. Sci. Eng. B (IF 3.507) Pub Date : 2019-12-23
    Hakikat Sharma; N.G. Deshpande; N.S. Negi

    Silicon (Si) is the most commonly used substrate material for fabricating integrated circuit; Si has very little fatigue effect. In the present work we developed pure NiFe2O4 and Cu, Co substituted NiFe2O4 thin films on Si substrate by metallo-organic decomposition (MOD) method using spin coating technique. The prepared thin films were characterized by XRD and Raman spectrometer for structural and phase identification. The topography and grain distribution of the prepared samples were analyzed by atomic force microscope (AFM). Magnetic hysteresis loops were measured at 10 K and 300 K using Superconducting quantum interference device (SQUID). The magnetization and coercive field increased with Cu, Co substitution. Temperature dependent magnetization (M-T) was carried out by zero-field cooled (ZFC) and field – cooled (FC) method. ZFC measurements revels that blocking temperature of the thin films is above 350 K.

  • Experimental data and modeling of electrical conductivity for polymer carbon nanotubes nanobiosensor during degradation in neutral phosphate-buffered saline (PBS)
    Mater. Sci. Eng. B (IF 3.507) Pub Date : 2019-12-12
    Yasser Zare; Kyong Yop Rhee

    This paper studies the conductivity of poly (lactic acid) (PLA)/poly (ethylene oxide) (PEO)/carbon nanotubes (CNT) nanocomposites during degradation in neutral phosphate-buffered saline (PBS) solution by experimental and modeling results. PLA/PEO/CNT nanocomposites are prepared and the conductivity of samples is measured before and during degradation. This system can be applied as a degradation nanobiosensor, because the variation of conductivity expresses the extent of degradation. A simple model is developed to predict the variation of conductivity during hydrolytic degradation. The degradation of polymers improves the effectiveness of CNT networks in the samples growing the conductivity. The proper agreement between experimental and theoretical results approves the validity of the developed model. A longer degradation time destroys more polymer chains shortening the tunneling space between CNT. The percolation threshold increases during degradation, due to the degradation of interphase zones between polymer and CNT. The calculations demonstrate that the fraction of networked CNT decreases during degradation, because PBS solution attacks the CNT networks. These reasonable predictions validate the developed equations representing the variations of conductivity, tunneling distance, percolation threshold and the fraction of networked CNT in the samples during degradation.

  • 更新日期:2019-12-11
  • One-step green route synthesis of spinel ZnMn2O4 nanoparticles decorated on MWCNTs as a novel electrode material for supercapacitor
    Mater. Sci. Eng. B (IF 3.507) Pub Date : 2019-12-09
    Kanakaraj Aruchamy, Radha Nagaraj, Halanur M. Manohara, Maalige R. Nidhi, Dibyendu Mondal, Debasis Ghosh, Sanna Kotrappanavar Nataraj

    This work focuses on designing new electrode materials by fabricating a nanocomposite hybrid of MWCNTs and a binary metal oxide, ZnMn2O4. The ZnMn2O4 has been extensively investigated as a high-performance anode in Li-ion battery, however, its capacitive faradaic charge storage behavior is rarely explored. Herein we demonstrate the fabrication of ZnMn2O4-CNT nanocomposites using acid modified MWCNTs and a one-step green hydrothermal method for supercapacitor application. The SEM analysis of the as-fabricated composites showed that the ZnMn2O4 nanoparticles were uniformly anchored on the MWCNTs backbone, which helps to maintain good electrical channel throughout the composite. Electrochemical characterizations were carried out in a three-electrode configuration in the 1 M Na2SO4 electrolyte in terms of cyclic voltammetry, galvanostatic charge discharge and electrochemical impedance spectroscopy analyses. The synergistic interaction between the MWCNTs and the ZnMn2O4 nanoparticles resulted in a high specific capacitance of 103 F/g of the as-fabricated electrode.

  • 更新日期:2019-12-05
  • Effect of alternative sonochemical treatment on zirconia surface and bond strength with veneering ceramic
    Mater. Sci. Eng. B (IF 3.507) Pub Date : 2019-12-03
    Natália Almeida Bastos, Paulo Noronha Lisboa-Filho, Americo Tabata, Paulo Afonso Silveira Francisconi, Adilson Yoshio Furuse, Heitor Marques Honório, Ana Flávia Sanches Borges
  • SEHC: A high-throughput materials computing framework with automatic self-evaluation filtering
    Mater. Sci. Eng. B (IF 3.507) Pub Date : 2019-12-03
    Wenhao Zhu, Yonglin Xu, Jianyue Ni, Guannan Hu, Xiangmeng Wang, Wu Zhang

    Efficiency is one of the key problems in the design of high-throughput materials computing. In this paper, we provide a Self-Evaluation High-throughput Computing framework (SEHC). The framework introduces an automatic self-evaluation filtering mechanism, which is based on machine learning, for high-throughput computing architectures to stop unexpected materials calculation tasks in advance during high-throughput calculation. The time-consuming high-throughput computing process is disassembled into several finer-grained high-throughput Stages. Multiple high-throughput Stages with the same standard design specifications can be assembled into a Pipeline model. Combined with the public service like data storage and system monitoring, the SEHC with a “Stage-Pipeline-Framework” three-tier structure is formed. To search for diamond-like structures with higher group velocity in a space of 254 compounds, a SEHC-based prototype was implemented. The experiment result shows that this prototype achieved a significant improvement in efficiency by reducing the amount of invalid computation remarkably.

  • Micromagnetic simulation of magnetic domain structures evolution of FeGa alloys by phase-field method
    Mater. Sci. Eng. B (IF 3.507) Pub Date : 2019-12-01
    Yanli Lu, Runan Guo, Tinghui Zhang, Zheng Chen
  • Converse piezoelectric behavior of three-dimensionally printed polymer and comparison of the in-plane and out-of-plane behavior
    Mater. Sci. Eng. B (IF 3.507) Pub Date : 2019-11-30
    Patatri Chakraborty, Chi Zhou, D.D.L. Chung

    The converse piezoelectric effect (out-of-plane and in-plane directions) is reported in 3D-printed polymer without filler or poling, consistent with previously reported direct piezoelectric effect (out-of-plane direction only). Resin 1 (acrylate ester, viscosity 95 cP) and Resin 2 (methacrylate, viscosity 2950 cP) are used in the printing by stereolithography. Both direct and converse effects stem from the 2D shear stress during printing causing 2D in-plane molecular alignment. Due to its higher viscosity, Resin 2 gives more molecular alignment and hence higher piezoelectric coupling coefficient d (0.4 vs. 0.2 pC/N). The out-of-plane d is similar for the direct and converse effects in the linear regime, which occurs below 30 kPa compressive stress in the direct effect and below 1 V/m in the converse effect. Both converse and direct effects are reversible, whether in the linear regime or not. The higher is the applied electric field, the lower is d, due to strain saturation.

  • Effect of dopant concentration on structural and optical properties of Cd0.7Zn0.3S semiconducting nanocrystals
    Mater. Sci. Eng. B (IF 3.507) Pub Date : 2019-11-28
    Indu Yadav, Dharamvir Singh Ahlawat

    Cu single doped and Cu, Mn co-doped Cd0.7Zn0.3S nanocrystals were synthesized successfully by co-precipitation method. XRD results confirmed hexagonal structure of as prepared Cu single doped and Cu, Mn co-doped Cd0.7Zn0.3S samples. The lattice constants, lattice plane, d-spacing, unit cell volume, Lorentz factor and dislocation density were also determined. The SEM analysis shows aggregation and nonuniform shapes of nanoparticles. The EDX spectra indicate the presence of S, Cd, Zn, Cu, Mn along with N and O in our samples. Absorption spectra shows maximum absorption in the range 209–236 nm with a shoulder peak at 277–299 nm which confirms a blue shift in comparison to bulk spectra. The photoluminescence (PL) spectra of Cu single doped samples shows blue-green emission centered at 428 and 488 nm. In Cu, Mn co-doped samples, higher intensity in blue green region at 458 and 488 nm attributed due to the sulfur vacancy and Zn defects respectively.

  • 更新日期:2019-11-29
  • Novel band gap engineered Bi5Nb3O15/N-rGOcomposite catalyst for photo degradation of reactive dyes
    Mater. Sci. Eng. B (IF 3.507) Pub Date : 2019-11-22
    Brindha Appavu, Sivakumar Thiripuranthagan, Thamaraiselvi Sureshkumar

    Niobate photo catalysts draw significant attention in the fields of both pollutant degradation and H2 generation. However, their chemically inert nature limits the synthetic routes available to obtain these semiconductors. In this work, we report the synthesis of bismuth niobate (Bi5Nb3O15) by a simple solvothermal method and incorporation of this material with nitrogen doped reduced graphene oxide for the first time. The synthesized catalysts were characterized by XRD, Raman, N2 adsorption-desorption isotherm, DRS-UV, FESEM and TEM analyses. XRD patterns exhibited single crystalline orthorhombic structure for Bi5Nb3O15. Electron microscopy showed plate-like structure for Bi5Nb3O15/N-rGO. UV–vis diffuse reflectance spectra revealed red shifting of reduced graphene oxide and nitrogen doped reduced graphene oxide composite catalysts indicating its visible activity. This novel Bi5Nb3O15/N-doped reduced graphene oxide showed higher photocatalytic decolorization of reactive dyes namely reactive blue 19 and reactive orange 16 under visible light than bare Bi5Nb3O15orBi5Nb3O15/rGO.

  • Evolution of phase pure magnetic cobalt ferrite nanoparticles by varying the synthesis conditions of polyol method
    Mater. Sci. Eng. B (IF 3.507) Pub Date : 2019-11-21
    Sathish Shanmugam, Balakumar Subramanian

    The mono-dispersed superparamagnetic CoFe2O4 nanoparticles have been prepared by polyol method at different synthesis conditions. The Raman results clearly emphasize that the samples prepared for 3 h reaction time alone have the peaks corresponding to pure CoFe2O4. The percentage of iron content was found to be high for sample prepared for 6 h (72.2%) reaction time compared to sample prepared for 12 h (65.4%). The atomic ratio between Co2+ and Fe3+ for samples prepared in 12 h reaction time is closer to 0.5 as expected from the CoFe2O4 stoichiometry but VSM data shows that sample prepared for 12 h reaction time have low magnetic saturation value. The increase of cobalt content and decrease of saturation value clearly emphasize that some changes have been occurred. Herein, we analyze and propose the possible reaction mechanism that could be occurred in different reaction time and thereby influencing the magnetic properties of the nanoparticles.

  • Dielectric and ferroelectric properties of Gd3+ doped (K0.5Na0.5)0.96Li0.04(Nb0.8Ta0.20)O3 piezoelectric ceramics
    Mater. Sci. Eng. B (IF 3.507) Pub Date : 2019-11-18
    Srinivas Pattipaka, Mahesh Peddigari, Pamu Dobbidi

    We report the structural, dielectric, ferroelectric and piezoelectric properties of Gd3+ doped lead-free (K0.5Na0.5)0.96Li0.04(Nb0.8Ta0.20)O3 (KNLNT) ceramics. The transition temperature (TT-C and TO-T) shifted towards the lower temperature (281 °C and 110 °C) for (K0.5Na0.5)0.92Li0.04Gd0.04(Nb0.8Ta0.20)O3 (KNLGNT) ceramics. Frequency dispersion of TT-C or TO-T suggests that KNLGNT ceramics exhibit a relaxor behavior supported by the Vogel-Fulcher law and modified Curie Weiss law. Temperature-dependent resistivity analysis shows that the conduction mechanism follows Mott’s variable range hopping with an average hopping length of 7.23 nm, hopping energy 0.46 eV and density of states near the Fermi level [N(EF)] = 129 × 1016 eV−1 cm−3 for KNLGNT ceramics. Reduction in leakage current and enhancement in dielectric (εr = 1025, tanδ = 0.061 at 1 MHz), ferroelectric properties (Pr = 23.14 μC/cm2, EC = 8.70 kV/cm at 1 Hz) and piezoelectric properties (kp (53%) and d33 (128 pC/N)) were observed for KNLGNT ceramics, which are promising for high-frequency piezoelectric devices.

  • Fabrication of novel magnetic F-TiO2(B)/carbon nanostructures nanocomposites as photocatalysts for malachite green degradation under visible light
    Mater. Sci. Eng. B (IF 3.507) Pub Date : 2019-11-14
    Nasser Arsalani, Yasaman Panahian, Ramin Nasiri

    Magnetic bronze F-TiO2/carbon nanostructures nanocomposites were facilely synthesized by using TTIP (titanium tetraisopropoxide) and carbon nanostructures (Multi-walled carbon nanotube (MWCNT) or Fullerene (C60)) as precursors via the hydrothermal process. The structure of the magnetic nanocomposites have been characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), UV–Vis diffuse reflectance spectroscopy, field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX) and Vibrating sample magnetometer (VSM). The photocatalytic activities of magnetic catalysts were evaluated by using the malachite green (MG) as contaminant. The results reveal that the photocatalytic degradation efficiency of F-TiO2(B)/Multiwall Carbon Nanotubes (MWCNT)@Nickel ferrite (NiFe2O4) and F-TiO2(B)/Fullerene(C60)@Nickel ferrite (NiFe2O4) for MG dye are 93% and 98% respectively, after 120 min visible irradiation. In addition, after using 4 times, the F-TiO2(B)/carbon nanostructure@NiFe2O4 nanocomposites still preserved an excellent degradation rate and indicated well reusability.

  • In situ synthesis of tower-like Ag-Sm(OH)3-ZnO photocatalyst with enhanced visible-light-driven photocatalytic activity
    Mater. Sci. Eng. B (IF 3.507) Pub Date : 2019-11-14
    Lixiong Yin, Changqing Liu, Jia Wang, Feifei Wang, Simin Chai, Dongdong Zhang, Xingang Kong, Huimin Li, Jianfeng Huang
  • 更新日期:2019-11-14
  • Effect of Ni substitution on structural, optical and magnetic properties of ferrite nanoparticles synthesized by co-precipitation route
    Mater. Sci. Eng. B (IF 3.507) Pub Date : 2019-11-14
    P. Iranmanesh, Sh. Tabatabai Yazdi, M. Mehran

    In this research, fine nanoparticles of NixFe3−xO4 with Ni concentration up to x = 1.5 were synthesized via a simple one-step capping agent-free co-precipitation route. The effect of Ni substitution was investigated by details using X-ray diffractometer, transmission electron microscope, Fourier transform infrared and UV–Vis spectroscope, and vibrating sample magnetometer. The structural studies revealed that the particles have good crystallinity with diameters of 7.5–13 nm with cubic spinel structure. The FTIR spectra exhibiting a doublet band around 600 cm−1 confirms further the mixed spinel structure. It was found that the involved nanoparticles are indirect band gap materials that controlled by the size effect rather than the influence of the chemical composition. The magnetic characterization showed that the nanoparticles are superparamagnetic at room temperature with the superior saturation magnetizations of about 68–70.5 emu/g; the size effects dominate the influence of the sites occupancy in controlling the magnetization values, as well.

  • A green luminescence of lemon derived carbon quantum dots and their applications for sensing of V5+ ions
    Mater. Sci. Eng. B (IF 3.507) Pub Date : 2019-11-14
    Bui Thi Hoan, Tran Thi Thanh, Phuong Dinh Tam, Nguyen Ngoc Trung, Sunglae Cho, Vuong-Hung Pham

    A simple approach for the synthesis of luminescent carbon dots (C-dots) has been developed by the hydrothermal treatment of lemon juice as carbon precursor at 240 °C in 12 h. The obtained C-dots were found to emit bright green luminescence. Meanwhile, the C-dots exhibited excitation-dependence, photo-stability, and well dispersibility. The C-dots were used for detection of ion V5+ in water and serum, which was based on V5+ induced luminescence quenching of C-dots. The selectivity experiments revealed that the luminescent sensor was specific for V5+ ions even with interference by high concentrations of other metal ions. Detection limits for V5+ ions was 3.2 ppm. These results suggest that the present C-dots are potential application in optoelectronic, imaging and luminescent probing of V5+ ions.

  • Highly electro-conductive graphene-decorated PANI-BiVO4 polymer-semiconductor nanocomposite with outstanding photocatalytic performance
    Mater. Sci. Eng. B (IF 3.507) Pub Date : 2019-11-14
    Md Rokon Ud Dowla Biswas, Kwang Youn Cho, Jae Doc Na, Won-Chun Oh

    Polyaniline/Bismuth Vanadate/Graphene Oxide (PANI-BiVO4-GO or BGPA) composite was prepared by sonochemical deposition of bismuth vanadate-graphene oxide (BiVO4) nanoparticles on the surface of polyaniline (PANI). The 5 wt% BGPA composite had the best photocatalytic degradation performances for MB, RhB, and SO dyes, about 1.56, 1.81, and 1.68 times more, respectively, than 1% BGPA composite. Meanwhile, the photocatalytic stability of BiVO4 was significantly improved by introducing PANI into the PANI-BiVO4-GO composite. These improvements in photocatalytic degradation performance and photocatalytic stability can be attributed to the formation of a heterojunction free electron between PANI and BiVO4-GO. The existence of these extra free electrons can dramatically enhance the efficiency of photogenerated electrons, thus accelerating the transfer of photogenerated holes from BiVO4-GO to PANI and constraining the self-oxidation of BiVO4.

  • Effect of lignin as accelerator of the biodegradation process of poly(lactic acid)/lignin composites
    Mater. Sci. Eng. B (IF 3.507) Pub Date : 2019-11-14
    Thaís Ferreira da Silva, Fernanda Menezes, Larissa Stieven Montagna, Ana Paula Lemes, Fabio Roberto Passador
  • 更新日期:2019-11-11
  • Phonon properties of multiferroic BiFeO3
    Mater. Sci. Eng. B (IF 3.507) Pub Date : 2019-11-10
    Xian-Sheng Cao

    The phonon properties of BiFeO3 have been studied by using the specific heat. It is found that the specific heat of BiFeO3 exhibits two peaks. The first peak appears at the magnetic phase transition temperature TN = 650 K. This anomaly in specific heat can be interpreted as antiferromagnetic transition. The values of the specific heat (at the magnetic phase transition temperature TN) increase with the increasing of the J1, |J2|, I and g. Another abnormal peak of specific heat appears at nearly 550 K, which is associated with the onset of structural changes. Note that the second peak shifts to lower temperature as the J1, |J2|, I and g decrease. It is considered that the main reason of leading to the structure distortion increases is due to the increase of the J1, |J2|, I and g. Those calculation conclusions are in accordance with the experimental results of other researchers.

  • Polypyrrole-Coated Polycaprolactone-Gelatin Conductive Nanofibers: Fabrication and Characterization
    Mater. Sci. Eng. B (IF 3.507) Pub Date : 2019-11-06
    Tahere Khatti, Hossein Naderi-Manesh, Seyed Mehdi Kalantar

    Electrically conductive nanofibrous meshes composed of polypyrrole, polycaprolactone and gelatin construct using a two-step approach including electrospinning and in situ polymerization. Nanometer-scale thick polypyrrole (PPy) is grown on the surface of electrospun polycaprolactone-gelatin (PCL-Gel) nanofiber by in situ chemical polymerization. Different PCL-to-gel ratios and fiber orientations are employed to construct template scaffolds for the coating reaction. SEM analysis indicates the fiber diameter of 162–207 nm and the coating thickness of 30–93 nm. Porosity estimation confirms conservation of total porosity in the coated mats. ATR-FTIR of the composite reveals that functional groups of all three polymers partially exist on the surface. Furthermore, XRD analysis verifies the crystalline nature of the hybrid scaffold. High electrical conductivity (4.6–5.8 S/cm) and convenient mechanical properties of the coated membranes are further achieved. The collective information of the current investigation introduces suitable potential candidates for diverse biomedical applications.

  • Experimental and theoretical study of thermoelectric properties of rhombohedral GeSb5Te10 thin films
    Mater. Sci. Eng. B (IF 3.507) Pub Date : 2019-11-01
    Athorn Vora-ud, Tosawat Seetawan, Manish Kumar
  • Cold sintering process for fabrication of a high volumetric capacity Li4Ti5O12 anode
    Mater. Sci. Eng. B (IF 3.507) Pub Date : 2019-10-28
    Joo-Hwan Seo, Kris Verlinde, Ramakrishnan Rajagopalan, Enrique D. Gomez, Thomas E. Mallouk, Clive A. Randall

    The cold sintering process (CSP) is useful for densifying lithium ion battery composite electrodes to achieve higher volumetric capacity density. Lithium titanate is one of the most promising anode materials to replace graphite in conventional anodes, as it enhances safety in large scale applications. A densified binder-free LTO based anode was fabricated by the cold sintering process. The composite anode was first formed by tape casting with a binder and then was heat treated to remove the binder. The binder-free composite was humidified with water to provide a transient liquid phase and then moved onto a current collector. The wetted composite was cold sintered at 120 °C under a uniaxial pressure of 500 MPa and directly deposited on a current collector. The density of the LTO/CNF composite anode was 2.82 g/cm3 (87% relative density). The volumetric capacity densities of the cold sintered anodes were found to be ~380 mAh/cm3.

  • 更新日期:2019-10-27
  • First principle study of mechanical stability, magneto-electronic and thermodynamic properties of double perovskites: A2MgWO6 (A = Ca, Sr)
    Mater. Sci. Eng. B (IF 3.507) Pub Date : 2019-10-25
    Shabir Ahmad Mir, Saleem Yousuf, Dinesh C. Gupta

    The first principle method within the framework of density functional theory is employed in order to explore the ground state structure along with electronic, elastic, and thermodynamic properties of double perovskites A2MgWO6 (A = Ca, Sr). Crystal structure optimization reveals nonmagnetic phase as stable state. The computed ground state parameters are consistent with the earlier results. Structural stability is further confirmed through computation of cohesive energy and elastic constants, where we have demonstrated the influence of cation size on various elastic constants. Band profile suggests indirect semiconducting behavior along Γ-X symmetric points for both perovskites. The contribution of different bands is explored through calculation of total and partial density of states. Effects of temperature and pressure on thermodynamic properties are predicted via the quasi-harmonic Debye model to convey the thermodynamic stability of oxides.

  • A novel temperature stable Mg0.5Ti0.5NbO4-based microwave dielectric material
    Mater. Sci. Eng. B (IF 3.507) Pub Date : 2019-10-11
    Liping Zhao, Peng Liu, Zhifen Fu
  • Effect of oxygen vacancies on photoluminescence and electrical properties of (2 0 0) oriented fluorine-doped SnO2 films
    Mater. Sci. Eng. B (IF 3.507) Pub Date : 2019-10-21
    Xuan Wang, Qingyin Di, Xiaolong Wang, Hongli Zhao, Bo Liang, Jingkai Yang
  • Low temperature sintering mechanism for Li2Mg3SnO6 microwave dielectric ceramics
    Mater. Sci. Eng. B (IF 3.507) Pub Date : 2019-10-23
    Zhifen Fu, Can Li, Jianli Ma, Yilong Wu

    Low-fired Li2Mg3SnO6 ceramics were fabricated via the conventional solid-state reaction route, and the effects of LiF-doping on their sintering mechanism and microwave dielectric properties were investigated. Sintering temperature of Li2Mg3SnO6 ceramics were effectively reduced to 900 °C due to the substitution of F− for O2−, which could cause weakening of oxygen bond strength induced reduced the intrinsic sintering temperature and facilitates the diffusion process. Low-fired ceramics inhibited volatilization of Li and improved relative density. Well-densified Li2Mg3SnO6-4 wt% LiF ceramics were obtained with optimum microwave dielectric properties of εr = 12.3, Q × f = 96280 GHz and τf = −40.7 ppm/°C at 900 °C. Such samples were compatible with Ag electrodes and suitable for LTCC applications.

  • Depth-resolved local atomic structure of Fe/Cr multilayer film with GMR effect: Experimental results
    Mater. Sci. Eng. B (IF 3.507) Pub Date : 2019-03-25
    Yu.A. Babanov, D.A. Ponomarev, D.I. Devyaterikov, E.Kh. Mukhamedzhanov, M.M. Borisov, M.V. Ryabukhina, I.E. Kantur, A.V. Korolev, M.A. Milyaev, L.N. Romashev, V.V. Ustinov, V.V. Vasin
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上海纽约大学William Glover