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Structural,mechanical,thermodynamic and electronic properties of Pt_(3)M(M=Al,Co,Hf,Sc,Y,Zr)compounds under high pressure

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Rare Metals 2021年第5期40卷 1208-1218页

作者： Zong-Bo Li Kai Xiong Cheng-Chen Jin Ying-Jie Sun Bao-Wen Wang Shun-Meng Zhang Jun-Jie He Yong Mao Materials Genome Institute National Center for International Research on Photoelectric and Energy MaterialsSchool of Materials and EnergyYunnan UniversityKunming 650091China

In this work,the impacts of pressure on the structural,mechanical,thermodynamic and electronic properties of typical Pt_(3)M(M=Al,Co,Hf,Sc,Y,Zr)compounds were investigated systematically by the firstprinciples density function theory calculations.The calculated lattice parameters,volume and elastic constants of Pt_(3)M compounds are in good agreement with available experimental and calculation values.With the increase in pressure,the lattice parameters and volume of Pt_(3)M compounds decrease,while the elastic constants,bulk modulus,shear modulus and Young’s modulus increase.The variations in Pugh’s ratio and Poisson’s ratio indicate that these Pt_(3)M compounds are mechanically stable and ductile.The mechanical anisotropy of these Pt_(3)M compounds is enhanced by rising pressure.Thermodynamic analysis indicates that sound velocity and Debye temperature increase with the increase in stress.The charge distribution does not change obviously,implying that no phase transition occurs in the range of 0-100 GPa.

关键词： Platinum intermetallic compounds elastic constants Anisotropy Debye temperature First-principles

Electronic and mechanical properties of half-metallic half-Heusler compounds CoCrZ(Z=S, Se, and Te)

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Chinese Physics B 2018年第1期27卷 501-507页

作者：黄海铭张传坤贺泽东张俊杨俊涛罗时军 School of Science and Advanced Functional Material and Photoelectric Technology Research Institution Hubei University of Automotive Technology

The electronic structures, magnetic properties, half-metallicity, and mechanical properties of half-Heulser compounds CoCrZ （Z = S, Se, and Te） were investigated using first-principles calculations within generalized gradient approximation based on the density function theory. The half-Heusler compounds show half-metallic properties with a half-metallic gap of 0.15 eV for CoCrS, 0.10 eV for CoCrSe, and 0.31 eV for CoCrTe at equilibrium lattice constant, respectively. The total magnetic moments are 3.00/-tB per formula unit, which agrees well with the Slater-Pauling rule. The half-metallicity, elastic constants, bulk modulus, shear modulus, Pough＇s ratio, Frantesvich ratio, Young＇s modulus, Poisson＇s ratio, and Debye temperature at equilibrium lattice constant and versus lattice constants are reported for the first time. The results indicate that the half-Heulser compounds CoCrZ （Z = S, Se, and Te） maintain the perfect half-metallic and mechanical stability within the lattice constants range of 5.18-5.43 A for CoCrS, 5.09-5.61 A for CoCrSe, and 5.17-6.42 A for CoCrTe, respectively.

关键词： half-Heusler half-metallicity elastic constants first-principles

Theoretical study of the elastic properties of titanium nitride

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Acta Metallurgica Sinica(English Letters) 2009年第2期22卷 146-152页

作者： Dong CHEN Jingdong CHEN Yinglu ZHAO Benhai YU Chunlei WANG Deheng SHI College of Physics and Electronic Engineering Xinyang Normal University Xinyang 464000 China College of Physics and Electronic Engineering Ludong University Yantai 264025 China

The equilibrium lattice parameter, relative volume V/V0, elastic constants Cij, and bulk modulus of titanium nitride are successfully obtained using the ab initio planewave pseudopotential （PW-PP） method within the framework of density functional theory. The quasi-harmonic Debye model, using a set of total energy vs molar volume obtained with the PW-PP method, is applied to the study of the elastic properties and vibrational effects. We analyze the relationship between the bulk modulus and temperature up to 2000 K and obtain the relationship between bulk modulus B and pressure at different temperatures. It is found that the bulk modulus B increases monotonously with increasing pressure and decreases with increasing temperature. Moreover, the Debye temperature is determined from the non-equilibrium Gibbs functions.

关键词： elastic constants Debye temperature Ab initio calculations Titanium nitride

Structural,phonon,elastic,thermodynamic and electronic properties of Mg-X(X=La,Nd,Sm)intermetallics:The first principles study

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Journal of Magnesium and Alloys 2019年第1期7卷 166-185页

作者： S.Rameshkumar G.Jaiganesh V.Jayalakshmi Department of Physics SRM Institute of Science and TechnologyRamapuram CampusChennai 600089India Materials Science Group Indira Gandhi Centre for Atomic ResearchKalpakkam 603102India

We show the results of first-principles calculations of structural,phonon,elastic,thermal and electronic properties of the Mg-X inter-metallics in their respective ground state phase and meta-stable phases at equilibrium geometry and the studied pressure range.Phonon dispersion spectra for these compounds were investigated by using the linear response technique.The phonon spectra do not show any abnormality in their respective ground state phase.The respective ground states phases of the studied system remain stable within the studied pressure range.Electronic and thermodynamic properties were derived by analysis of the electronic structures and quasi-harmonic approximation.The mixed bonding character of the Mg-X intermetallics is revealed by Mg-X bonds,and it leads the metallic nature.Most of the contribution originated from X ions d like states at Fermi level compared to that of Mg ion in these intermetallics.In this work,we also predicted the melting temperature of these intermetallics and evaluated the Debye temperature by using elastic constants.

关键词： Mg-X intermetallics First principle calculation Heat of formation elastic constants Electronic and phonon properties Thermodynamic property

Electronic structure calculations of rare-earth intermetallic compound YAg using ab initio methods

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Journal of Rare Earths 2009年第4期27卷 664-666页

作者： S.Ugur G.Ugur F.Soyalp R.Ellialt1oglu Department of Physics Gazi University Teknikokullar Ankara 06500 Turkey Department of Physics Yüzüncü Yll University Zeve Kampüsü Van 65080 Turkey Department of Physics Engineering Hacettepe University Beytepe Ankara 06800 Turkey

The structural, elastic and electronic properties of YAg-B2（CsCl） were investigated using the first-principles calculations. The energy band structure and the density of states were studied in detail, including partial density of states （PDOS）, in order to identify the character of each band. The structural parameters （lattice constant, bulk modulus, pressure derivative of bulk modulus） and elastic constants were also obtained. The results were consistent with the experimental data available in the literature, as well as other theoretical results.

关键词： YAg electronic band structure density of states elastic constants ab initio rare earths

First-principles investigation of the effects of strain on elastic thermal, and optical properties of CuGaTe2

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Chinese Physics B 2017年第6期26卷 324-328页

作者：薛丽任一鸣何俊荣徐四六 School of Electronic and Information Engineering Hubei University of Science and Technology Xianning 437100 China

Based on the density functional theory, the influences of strain on structural, elastic, thermal and optical properties of CuGaTe2 are discussed in detail. It is found that the tensile strain on CuGaTe2 is beneficial to the decrease of lattice thermal conductivity by reducing the mean sound velocity and Debye temperature. Moreover, all strained and unstrained CuGaTe2 exhibit rather similar optical characters. But the tensile strain improves the ability to absorb sunlight in the visible range.These research findings can give hints for designing thermoelectric and photovoltaic devices.

关键词： elastic constants thermal properties optical properties first-principles

Compositional dependence of thermal and elastic properties of Cu-Ti-Zr-Ni bulk metallic glasses

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International Journal of Minerals,Metallurgy and Materials 2010年第3期17卷 318-322页

作者： Jihye An Hyunjune Yim Choi-Yim Haein Department of Physics Sookmyung Women's University Department of Mechanical & System Design Engineering Hongik University

Starting from the quaternary Cu47Ti34Zr11Ni8 alloy, the compositional dependence of thermal and elastic properties of Cu-Ti-Zr-Ni alloys was systematically investigated. Quaternary Cu-Ti-Zr-Ni alloys can be cast directly from the melt into copper molds to form fully amorphous strips or rods with the thickness of 3-6 mm. The evidence of the amorphous nature of the cast rods was provided by X-ray spectra. The measured glass transition temperature （Tg） and crystallization temperature （Tx） were obtained for the alloys using differential scanning calorimetry （DSC） at the heating rate of 20 K/s. In the results, the differences between the glass temperature and the crystallization temperature （△Tx=Tx-Tg） are measured with values ranging up to 33-55 K. The reduced glass transition temperature （Trg）, which is the ratio of the glass temperature to the liquidus temperature （T3, is often used as an indication of the glass-forming ability of metallic alloys. For the present Cu-Ti-Zr-Ni alloys, this ratio is typically in the range of 0.5838-0.5959, characteristic of metallic alloys with good glass-forming ability. The elastic constants for several selected alloys were measured using ultrasonic methods. The values of the elastic shear modulus, bulk modulus, and Poisson＇s ratio were also given.

关键词： bulk metallic glasses （BMGs） quatemary alloys elastic constants glass-forming ability

Structural,electronic,optical,elastic properties and Born effective charges of monoclinic HfO_2 from first-principles calculations

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Chinese Physics B 2014年第4期23卷 496-503页

作者：刘其军张宁超刘福生刘正堂 Bond and Band Engineering Group Institute of High Temperature and High Pressure Physics School of Physical Science and TechnologySouthwest Jiaotong University State Key Laboratory of Solidification Processing School of Materials Science and EngineeringNorthwestern Polytechnical University

First-principles calculations of structural, electronic, optical, elastic, mechanical properties, and Born effective charges of monoclinic HfO2 are performed with the plane-wave pseudopotential technique based on the density-functional theory. The calculated structural properties are consistent with the previous theoretical and experimental results. The electronic structure reveals that monoclinic HfO2 has an indirect band gap. The analyses of density of states and Mulliken charges show mainly covalent nature in Hf-O bonds. Optical properties, including the dielectric function, refractive index, extinction coefficient, reflectivity, absorption coefficient, loss function, and optical conductivity each as a function of photon energy are calculated and show an optical anisotropy. Moreover, the independent elastic constants, bulk modulus, shear modulus, Young＇s modulus, Poisson＇s ratio, compressibility, Lam6 constant, sound velocity, Debye temperature, and Born effective charges of monoclinic HfO2 are obtained, which may help to understand monoclinic HfO2 for future work.

关键词： density-functional theory optical properties elastic constants monoclinic HfO2

Structural, electronic, elastic, and thermal properties of CaNiH3 perovskite obtained from first-principles calculations

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Chinese Physics B 2018年第3期27卷 384-390页

作者： S Benlamari H Bendjeddou R Boulechfar SAmara Korba H Meradji R Ahmed S Ghemid R Khenata S Bin Omran Laboratoire LPR Departement de Physique Faculté des Sciences Université Badji Mokhtar Annaba Algeria Department of Physics Faculty of Science Universiti Teknologi Malaysia UTM Skudai 81310 Johor Malaysia Laboratoire de Physique Quantique et de Modelisation Mathematique de la Matiere (LPQ3M) Universite de Mascara-29000-Algeria Department of Physics and Astronomy College of Science King Sand University P.O. Box 2455 Riyadh 11451 Saudi Arabia

A theoretical study of the structural, elastic, electronic, mechanical, and thermal properties of the perovskite-type hydride CaNiH3 is presented. This study is carded out via first-principles full potential （FP） linearized augmented plane wave plus local orbital （LAPW＋lo） method designed within the density functional theory （DFT）. To treat the exchange-correlation energy/potential for the total energy calculations, the local density approximation （LDA） of Perdew-Wang （PW） and the generalized gradient approximation （GGA） of Perdew-Burke-Ernzerhof （PBE） are used. The three independent elastic constants （C11, C12, and C44） are calculated from the direct computation of the stresses generated by small strains. Besides, we report the variation of the elastic constants as a function of pressure as well. From the calculated elastic constants, the mechanical character of CaNiH3 is predicted. Pertaining to the thermal properties, the Debye temperature is estimated from the average sound velocity. To further comprehend this compound, the quasi-harmonic Debye model is used to analyze the thermal properties. From the calculations, we find that the obtained results of the lattice constant （ao）, bulk modulus （Bo）, and its pressure derivative （B0′） are in good agreement with the available theoretical as well as experimental results. Similarly, the obtained electronic band structure demonstrates the metallic character of this perovskite-type hydride.

关键词： perovskite-type hydrides elastic constants hydrogen storage materials