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Investigation on the crystal structure and mechanical properties of the ternary compound Mg_(11-x)Zn_(x)Sr combined with experimental measurements and first-principles calculations

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Journal of Magnesium and Alloys 2023年第3期11卷 1074-1082页

作者： Jian Wang Lingzhong Meng Zhang Zhang Baisheng Sa Xiaoxiao Fu Liyuan Sheng Daokui Xu Yufeng Zheng School of Mechanical Engineering Yangzhou UniversityYangzhou 225127China Key Laboratory of Eco-materials Advanced Technology College of Materials Science and EngineeringFuzhou UniversityFuzhou 350108China College of Materials Science and Engineering Chongqing UniversityChongqing 400044China Shenzhen Institute Peking UniversityShenzhen518057China PKU-HKUST ShenZhen-HongKong Institution Shenzhen 518057China Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang110016China

A new ternary compound,Mg_(11-x)Zn_(x)Sr in the Mg-Zn-Sr system was observed and studied using Scanning Electron Microscopy(SEM),Energy-Dispersive Spectroscope(EDS),X-Ray Diffraction(XRD)and Transmission Electron Microscopy(TEM).The XRD patterns were refined by the Rietveld refinement method and the results revealed that the crystallized Mg_(11-x)Zn_(x)Sr phase belonged to tetragonal I41/amd space group and had the Cd_(11)Ba prototype.The Mg atoms were successfully doped into Zn_(11)Sr crystal lattice by occupying Zn atomic sites.Moreover,the Rietveld refinement and computational results demonstrated a gradual decrease in the a-axis and c-axis lattice parameters with decreasing concentration levels of Mg coordination substitution in the lattice of Mg_(11-x)Zn_(x)Sr compound.The elastic constants and modulus of the Mg_(11-x)Zn_(x)Sr compounds calculated by first-principles calculations(FPC)indicated they were increased with the increasing of Zn content.The variation of hardness,D-band widths and the total density of states for Mg_(11-x)Zn_(x)Sr compounds with Zn content was discussed.

关键词： Mg-Zn-Sr system Crystal structure Hardness elastic constants Modulus

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Frist-principles prediction of elastic, electronic,and thermodynamic properties of high entropy carbide ceramic (TiZrNbTa)C

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Rare Metals 2022年第3期41卷 1002-1014页

作者： Kai Xiong Bao-Wen Wang Ze-Peng Sun Wei Li Cheng-Chen Jin Shun-Meng Zhang Si-Yong Xu Lei Guo Yong Mao National Center for International Research on Photoelectric and Energy Materials School of Materials and EnergyMaterials Genome InstituteYunnan UniversityKunming 650091China Advanced Computing Center Information Technology CenterYunnan UniversityKunming 650091China

High-entropy carbide ceramics (HECs) have drawn increasing attention as their excellent mechanical and thermal properties. In this work, the crystal stability,mechanical behavior, electronic and thermodynamic properties of (TiZrNbTa)C HEC are investigated by the first-principles calculations. Obtained results reveal that the disordered transition-metal (TM) atoms result in serious local lattice distortion within the crystal. The lattice distortion plays a key role for the structural stabilization,mechanical anisotropy and thermodynamic behaviors of(TiZrNbTa)C. Increasing pressure leads to decrease the lattice parameter, volume and brittleness, meanwhile increase the elastic constants, elastic moduli, mechanical anisotropy, sound velocity, and Debye temperature. It is also discovered that charge delocalization occurs with the increase in pressure. The mechanical stability and anisotropy of (TiZrNbTa)C are attributed primarily to TM-C bonding.

关键词： High-entropy carbide ceramics elastic constants Anisotropy Thermodynamic First-principles

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The anisotropy of hexagonal close-packed iron under inner core conditions: the effect of light elements

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Earth and Planetary Physics 2022年第4期6卷 399-423页

作者： Wei Zhang Mei Tang ZhenWei Niu Laboratory for Extreme Conditions Matter Properties Southwest University of Science and TechnologyMianyang Sichuan 621010China Fundamental Science on Nuclear Wastes and Environmental Safety Laboratory Southwest University of Science and TechnologyMianyang Sichuan 621010China School of National Defense Science&Technology Southwest University of Science and TechnologyMianyang Sichuan 621010China

In recent decades,global seismic observations have identified increasingly complex anisotropy of the Earth’s inner core.Numerous seismic studies have confirmed hemispherical variations in the inner core’s anisotropy.Here,based on ab initio molecular dynamics calculations,we report how the anisotropy of hexagonal close-packed(hcp)-iron,under inner core conditions,could be altered when alloyed with light elements.We find that light elements in binary allows with iron-hcp-Fe-X(X=C,O,Si,and S)-could have significant effects on density,sound velocities,and anisotropy,compared with the behavior of pure hcp-iron;the anisotropy of these binary alloys depends on combined effects of temperature and the particular alloying light element.Furthermore,the change in anisotropy strength with increasing temperature can be charted for each alloy.Alloying pure iron with some light elements such as C or O actually does not increase but decreases core anisotropy at high temperatures.But the light element S can significantly enhance the elastic anisotropy strength of hcp-Fe.

关键词： iron elastic constants anisotropy inner core

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THE MEASUREMENT OF elastic constants OF QUARTZ CRYSTAL BY RESONANT ULTRASOUND SPECTROSCOPY

THE MEASUREMENT OF ELASTIC CONSTANTS OF QUARTZ CRYSTAL BY RE...

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2012全国压电和声波理论及器件技术研讨会

作者： Zhen WANG Ji WANG Xiang-wu XU Jian-ke DU Ting-feng MA Piezoelectric Device Laboratory School of Mechanical Engineering ＆ MechanicsNingbo University

The mechanical resonant response of a solid depends on its shape,density,and elastic moduli.We describe here the instrumentation and computational methods for obtaining and analyzing the resonant frequency of very small（0.001 cm3）samples,and provide examples to demonstrate the utilization of the technique.A new material type with six independent elastic constants are formulated and tested with the instrumentation.This study will leads to expansion of the software capability for the testing of novel materials.

关键词： elastic constants Resonant Ultrasound Spectroscopy Quartz crystal Levenberg-Marquardt method

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THE DEVELOPMENT OF A GENERAL ANISOTROPIC MATERIAL MODEL WITH RESONANT ULTRASOUND SPECTROSCOPY TECHNOLOGY FOR THE MEASUREMENT OF elastic constants OF PIEZOELECTRIC CRYSTALS

THE DEVELOPMENT OF A GENERAL ANISOTROPIC MATERIAL MODEL WITH...

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2013全国压电和声波理论及器件技术研讨会

作者： Zhen WANG Ji WANG Yanqing ZHENG Fapeng YU Sergei ZHGOON Tingfeng MA Piezoelectric Device Laboratory School of Mechanical Engineering & MechanicsNingbo University Shanghai Institute of Ceramics Chinese Academy of Sciences State Key Laboratory of Crystal Materials and Institute of Crystal Materials Shandong University National research University Moscow Power Engineering Institute

The mechanical resonant response of a solid depends on its shape,density,and elastic moduli.We describe here the computational methods based on a general anisotropic material model for obtaining and analyzing the resonant frequencies of small samples,and provide examples to demonstrate the utilization and validation.Two new material types with six and thirteen independent elastic constants are formulated and tested with the instrumentation.This study will lead to expansion of software capability for the testing of novel materials with current instrumentation.

关键词： elastic constants RUSpec Technology Quartz Crystal Levenberg-Marquardt Method

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CHARACTERIZATIONS OF elastic constants OF TRANSPARENT THIN FILMS DEPOSITED ON SUBSTRATES BY LASER ULTRASONIC METHOD

CHARACTERIZATIONS OF ELASTIC CONSTANTS OF TRANSPARENT THIN F...

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第三届全国压电和声波理论及器件技术研讨会

作者： Kiyotaka WASA Lab of Modern Acoustics Institute of AcousticsNanjing University NanjingJiangsu 210093China Department of Micro-Engineering Kyoto UniversityKyoto 606-8501Japan

A laser generation and optical difference detection method of surface acoustic waves is used for characterizing elastic constants of thin films deposited on substrates.The film/substrate samples are prepared by a RF magnetron sputtering technique.Teflon-like films,deposited on three kinds of substrates,silicone plates,glass and copper plates,have been studied and the related parameters have been evaluated.

关键词： Laser-ultrasonics thin films elastic constants

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First-principles investigation on the structural and elastic properties of cubic-Fe_2 TiAl under high pressures

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Chinese Physics B 2013年第8期22卷 557-562页

作者：刘显坤刘聪郑洲兰晓华 Institute of Nuclear Physics and Chemistry China Academy of Engineering Physics

The structural, elastic, and thermodynamic properties of cubic-Fe2TiA1 under high temperatures and pressures are investigated by performing ab initio calculation and using the quasi-harmonic Debye model. Some ground state properties such as lattice constant, bulk modulus, pressure derivative of the bulk modulus, and elastic constants are in good agreement with the available experimental results and theoretical data. The thermodynamic properties of Fe2TiA1 such as thermal expansion coefficient, Debye temperature, and heat capacity in ranges of 0 K-1200 K and 0 GPa-250 GPa are also obtained. The calculation results indicate that the heat capacities at different pressures all increase with temperature increasing and are close to the Dulong-Petit limit at higher temperatures, Debye temperature decreases with temperature increasing, and increases with pressure rising. The cubic-FezTiA1 is stable mechanically under 250 GPa. Moreover, under lower pressure, thermal expansion coefficient rises rapidly with temperature increasing, and the increasing rate becomes slow at higher pressure.

关键词： Fe2TiA1 first principles elastic constants thermodynamics properties

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First-principles investigations on elastic and thermodynamic properties of zinc-blende structure BeS

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Chinese Physics B 2008年第4期17卷 1377-1382页

作者：常景陈向荣张伟朱俊 College of Physical Science and Technology Sichuan University International Centre for Materials Physics Chinese Academy of Sciences

In this paper the elastic and thermodynamic properties of the cubic zinc-blende structure BeS at different pressures and temperatures are investigated by using ab initio plane-wave pseudopotential density functional theory method within the generalized gradient approximation （GGA）. The calculated results are in excellent agreement with the available experimental data and other theoretical results. It is found that the zinc-blende structure BeS should be unstable above 60GPa. The thermodynamic properties of the zinc-blende structure BeS are predicted by using the quasi-harmonic Debye model. The pressure-volume-temperature （P - V - T） relationship, the variations of the thermal expansion coefficient α and the heat capacity Cv with pressure P and temperature T, as well as the Gruneisen parameter-pressure-temperature （γ- P - T） relationship are obtained systematically in the ranges of 0-90GPa and 0-2000K.

关键词： density functional theory elastic constants thermodynamic properties Griineisen parameter BeS

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First-principles study of the structural,mechanical and electronic properties of ZnX_2O_4(X=Al,Cr and Ga)

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Chinese Physics B 2011年第4期20卷 408-414页

作者：张良姬广富赵峰龚自正 Science and Technology of Shock Wave and Detonation Physics Laboratory Institute of Fluid PhysicsChinese Academy of Engineering Physics College of Physical Science and Technology Sichuan University Beijing Institute of Spacecraft Environment Engineering

This paper performs first-principles calculations to study the structural, mechanical and electronic properties of the spinels ZnA1204, ZnGa2O4 and ZnCr2O4, using density functional theory with the plane-wave pseudopotential method. Our calculations are in good agreement with previous theoretical calculations and the available experimental data. The studies in this paper focus on the evolution of the mechanical properties of ZnAl2O4, ZnGa2O4 and ZnCr2O4 under hydrostatic pressure. The results show that the cubic phases of ZnAl2O4, ZnCa2O4 and ZnCr2O4 become unstable at about 50 GPa, 40 GPa and 25 GPa, respectively. From analysis of the band structure of the three compounds at equilibrium volume, it obtains a direct band gap of 4.35 eV for ZnA1204 and 0.89 cV for ZnCr2O4, while ZnGa2O4 has an indirect band gap of 2.73 eV.

关键词： first-principles calculation phase transition elastic constants bandstructure

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Effects of pressure on structural, electronic, and mechanical properties of α,β,and γ uranium

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Chinese Physics B 2017年第6期26卷 288-294页

作者：张慧杰李世娜郑晶晶李卫东王保田 Institute of Theoretical Physics and Department of Physics Shanxi University Talyuan 030006 China Institute of High Energy Physics Chinese Academy of Sciences (CAS) Beijing 100049 China Dongguan Neutron Science Center Dongguan 523803 China

The first-principles methods have been employed to calculate the structural, electronic, and mechanical properties of the α, β, and γ phases of uranium under pressure up to 100 GPa. The electronic structure has been viewed in forms of density of states and band structure. The mechanical stability of metal U in the α, β, and γ phases have been examined.The independent elastic constants, polycrystalline elastic moduli, as well as Poisson＇s ratio have been obtained. Upon compression, the elastic constants, elastic moduli, elastic wave velocities, and Debye temperature of α phase are enhanced pronouncedly. The value of B/G illustrates that α and γ phases are brittle in ground state.

关键词： first-principles structural parameters electronic structure elastic constants

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