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Density functional theory investigation on lattice dynamics,elastic properties and origin of vanished magnetism in Heusler compounds CoMnVZ(Z=Al,Ga)

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Chinese Physics B 2021年第8期30卷 301-311页

作者： Guijiang Li Enke Liu Guodong Liu Wenhong Wang Guangheng Wu College of Materials Science and Engineering Nanjing Tech UniversityNanjing 211816China State Key Laboratory for Magnetism Institute of PhysicsChinese Academy of SciencesBeijing 100190China Songshan Lake Materials Laboratory Dongguan 523808China School of Materials Science and Engineering Hebei University of TechnologyTianjin 300130China

The lattice dynamics,elastic properties and the origin of vanished magnetism in equiatomic quaternary Heusler compounds CoMnVZ(Z=Al,Ga)are investigated by first principle calculations in this *** to the similar constituent atoms in CoMnVAl and CoMnVGa compounds,they are both stable in LiMgPdSn-type structure with comparable lattice size,phonon dispersions and electronic ***,we find that CoMnVAl is more structurally stable than ***,the increased covalent bonding component in CoMnVAl enhances its mechanical strength and Vickers hardness,which leads to better comprehensive mechanical properties than those of *** and importantly,structural and chemical compatibilities at the interface make non-magnetic semiconductor CoMnVAl and magnetic topological semimetals Co2MnAl/Ga more suitable to be grown in *** to atomic preferential occupation in CoMnVAl/Ga,the localized atoms Mn occupy C(0.5,0.5,0.5)Wyckoff site rather than B(0.25,0.25,0.25)and D(0.75,0.75,0.75)Wyckoff sites in LiMgPdSn-type structure,which results in symmetric band filling and consequently drives them to be ***,by tuning localized atoms Mn to occupy B(0.25,0.25,0.25)or/and D(0.75,0.75,0.75)Wyckoff sites in off-stoichiometric Co-Mn-V-Al/Ga compounds and keeping the total valence electrons as 24,newly compensated ferrimagnetic compounds are theoretically *** hope that our work will provide more choices for spintronic applications.

关键词： Heusler compounds CoMnVAl/Ga first principles calculations lattice dynamics elastic properties nonmagnetic semiconductor

Effect of pressure on the elastic properties and optoelectronic behavior of Zn_4B_6O_(13): First-principles investigation

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Chinese Physics B 2018年第5期27卷 430-439页

作者： Pei-Da Wang Zhen-Yuan Jia Yu-Han Zhong Hua-Yue Mei Chun-Mei Li Nan-Pu Cheng Faculty of Materials and Energy Southwest University Chongqing 400715 China

The hydrostatic-pressure-dependent mechanical stability and optoelectronic behavior of Zn_4B_6O_（13）（ZBO） are calculated using the exchange-correlation functional Perdew–Burke–Ernzerhof generalized gradient approximation and the hybrid functional PBE0 based on density functional theory. The calculated and experimental unit cell volumes and Vickers hardness of ZBO at zero pressure agree well. ZBO is mechanically stable under the critical pressure of 52.98 GPa according to the generalized stability criteria. Furthermore, Young＇s modulus and Vickers hardness decrease with increasing hydrostatic pressure. The strength and type of ZBO bonds are investigated by population and electron density difference. The electronic structure at zero pressure reveals that ZBO is an indirect band gap semiconductor, and the calculated 5.62-e V bandgap coincides well with the 5.73-e V experimental value, highlighting the success of the hybrid functional PBE0 calculations of electronic properties. The band gap almost increases as a second-order polynomial of pressure, and the indirect nature does not change with the applied external pressure. The optical reflectivity and absorption coefficient show that ZBO is an excellent ultraviolet photodetector. Our calculation results suggest that the elastic and optical properties of ZBO are highly stable over a wide pressure range.

关键词： Zn4B6O13 crystal density functional theory elastic properties optical properties

Thermodynamics and elastic properties of Ta from first-principles calculations

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Chinese Physics B 2012年第12期21卷 412-419页

作者：李强黄多辉曹启龙王藩侯蔡灵仓张修路经福谦 Computational Physics Key Laboratory of Sichuan Province Yibin University Key Laboratory of National Defense Science and Technology for Shock Wave and Detonation Physics and the Science

Within the framework of the quasiharmonic approximation, the thermodynamics and elastic properties of Ta, including phonon density of states （DOS）, equation of state, linear thermal expansion coefficient, entropy, enthalpy, heat capacity, elastic constants, bulk modulus, shear modulus, Young＇s modulus, microhardness, and sound velocity, are studied using the first-principles projector-augmented wave method. The vibrational contribution to Helmholtz free energy is evaluated from the first-principles phonon DOS and the Debye model. The thermal electronic contribution to Helmholtz free energy is estimated from the integration over the electronic DOS. By comparing the experimental results with the calculation results from the first-principles and the Debye model, it is found that the thermodynamic properties of Ta are depicted well by the first-principles. The elastic properties of Ta from the first-principles are consistent with the available experimental data.

关键词： first-principles Ta thermodynamics Debye model elastic properties

First principles investigation of binary intermetallics in Mg-Al-Ca-Sn alloy:Stability,electronic structures,elastic properties and thermodynamic properties

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Transactions of Nonferrous Metals Society of China 2016年第1期26卷 203-212页

作者：王峰孙士杰于波张峰毛萍莉刘正沈阳工业大学材料科学与工程学院沈阳110870

The structural stability, electronic structures, elastic properties and thermodynamic properties of the main binary phases Mg_（17）Al_（12）, Al_2Ca, Mg_2 Sn and Mg_2 Ca in Mg-Al-Ca-Sn alloy were determined from the first-principles calculation. The calculated lattice parameters are in good agreement with the experimental and literature values. The calculated heats of formation and cohesive energies show that Al_2Ca has the strongest alloying ability and structural stability. The densities of states（DOS）, Mulliken electron occupation number, metallicity and charge density difference of these compounds are given. The elastic constants of Mg_（17）Al_（12）, Al_2Ca, Mg_2 Sn and Mg_2 Ca phases are calculated, and the bulk moduli, shear moduli, elastic moduli and Poisson ratio are derived. The calculations of thermodynamic properties show that the Gibbs free energies of Al_2Ca and Mg_2 Sn are lower than that of Mg_（17）Al_（12）, which indicates that Al_2Ca and Mg_2 Sn are more stable than Mg_（17）Al_（12） phase. Hence, the heat resistance of Mg-Al-based alloys can be improved by adding Ca and Sn additions.

关键词： Mg-Al alloy first-principles calculation electronic structure elastic properties thermodynamic properties

Ab initio study of the electronic structure and elastic properties of Al_5C_3N

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Chinese Physics B 2011年第12期20卷 309-314页

作者：徐学文胡龙宇霄卢遵铭范英李养贤唐成春 School of Materials Science and Engineering Hebei University of Technology

We investigate the electronic structure, chemical bonding and elastic properties of the hexagonal aluminum carbonitride, Al5C3N, by ab initio calculations. Al5C3N is a semiconductor with a narrow indirect gap of 0.81 eV. The valence bands below the Fermi level （EF） originate from the hybridized Al p-C p and A1 p-N p states. The calculated bulk and Young＇s moduli are 201 GPa and 292 GPa, which are slightly lower than those of Ti3SiC2. The values of the bulk-to-shear-modulus and bulk-modulus-to-c44 are 1.73 and 1.97, respectively, which are higher than those of Ti2AlC and Ti2AlN, indicating that Al5C3N is a ductile ceramic.

关键词： electronic structure chemical bonding elastic properties ductility

Hybrid DFT study of structural,electronic,magnetic and elastic properties of laves phase binary intermetallics RFe_(2)(R=La,Ce,Pr and Nd)

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稀土学报:英文版 2023年第9期41卷 1367-1375,I0004页

作者： Murad Murad Zahid Ali Muhammad Idrees Centre for Computational Materials Science Department of PhysicsUniversity of MalakandChakdaraDir(Lower)18800KPPakistan

Hybrid density functional theory was used to investigate the structural,electronic,magnetic and elastic properties of the Laves phase binary intermetallics RFe_(2)(R=La,Ce,Pr and Nd) in C_(15) crystal *** calculated lattice constants of these materials are found in good agreement with the *** band structures and density of states distribution confirm the metallic nature of all these *** optimized energies in different magnetic phases and magnetic susceptibilities by postDFT treatments confirm that all the understudy compounds are ferromagnetic in *** parameters were calculated from the cubic elastic coefficients C_(11),C_(12) and C_(44).The elastic properties reveal that these intermetallics are incompressible,ductile,elastically anisotropic and mechanically *** on the metallic nature and ferromagnetic properties,it is expected that these intermetallics are suitable materials for spintronic technology.

关键词： Intermetallics Laves phase Density functional theory Electronic band structures Magnetic properties elastic properties

Density-functional theory study of the effect of pressure on the elastic properties of CaB_6

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Chinese Physics B 2013年第7期22卷 420-425页

作者：韩晗 Surface Physics Laboratory (National Key Laboratory) Key Laboratory of Computational Physical Sciencesand Department of PhysicsFudan University

Under high pressure, the long believed single-phase material CaB6 was latterly discovered to have a new phase tI56. Based on the density-functional theory, the pressure effects on the structural and elastic properties of CaB6 are obtained. The calculated bulk, shear, and Young’s moduli of the recently synthesized high pressure phase tI56-CaB6 are larger than those of the low pressure phase. Moreover, the high pressure phase of CaB6 has ductile behaviors, and its ductility increases with the increase of pressure. On the contrary, the calculated results indicate that the low pressure phase of CaB6 is brittle. The calculated Debye temperature indicates that the thermal conductivity of CaB6 is not very good. Furthermore, based on the Christoffel equation, the slowness surface of the acoustic waves is obtained.

关键词： density-functional theory elastic properties pressure effects acoustic properties

High-pressure structure and elastic properties of tantalum single crystal:First principles investigation

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Chinese Physics B 2016年第12期25卷 350-356页

作者：顾建兵王臣菊张旺玺孙斌刘国群刘丹丹杨向东 School of Materials and Chemical Engineering Zhongyuan University of Technology College of Science Zhongyuan University of Technology Institute of Atomic and Molecular Physics Sichuan University

Since knowledge of the structure and elastic properties of Ta at high pressures is critical for addressing the recent controversies regarding the high-pressure stable phase and elastic properties, we perform a systematical study on the highpressure structure and elastic properties of the cubic Ta by using the first-principles method. Results show that the initial body-centered cubic phase of Ta remains stable even up to 500 GPa and the high-pressure elastic properties are excellent/y consistent with the available experimental results. Besides, the high-pressure sound velocities of the single- and polycrystals Ta are also calculated based on the elastic constants, and the predications exhibit good agreement with the existing experimental data.

关键词： high-pressure structure elastic properties sound velocities density functional theory

First-principles calculations for elastic properties of rutile TiO_2 under pressure

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Chinese Physics B 2008年第6期17卷 2216-2221页

作者：朱俊于景新王艳菊陈向荣经福谦 College of Physical Science and Technology Sichuan University Institute of Atomic and Molecular Physics Sichuan University Laboratory for Shock Wave and Detonation Physics Research Institute of Fluid Physics Chinese Academy of Engineering Physics

This paper studies the equilibrium structure parameters and the dependences of the elastic properties on pressure for rutile TiO2 by using the Cambridge Serial Total Energy Package （CASTEP） program in the frame of density functional theory. The obtained equilibrium structure parameters, bulk modulus B0 and its pressure derivative B′0 are in good agreement with experiments and the theoretical results. The six independent elastic constants of rutile TiO2 under pressure are theoretically investigated for the first time. It is found that, as pressure increases, the elastic constants C11, C33, C66, C12 and C13 increase, The variation of elastic constant C44 is not obvious and the anisotropy will weaken.

关键词： density functional theory elastic properties TiO2