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Phase Stability,elastic,Thermo-physical and Electronic Properties of Hexa-(Mo,Cr,W)_2C from First-principles Calculations

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Journal of Iron and Steel Research International 2016年第10期23卷 1096-1103页

作者： Di WU Wan-tang FU Yong LI Chun-xu WANG Jing-lin TANG College of Mechanical Engineering Yanshan University Institute for Structural Materials Central Iron and Steel Research Institute State Key Laboratory of Metastable Materials Science and Technology Yanshan University

Phase stability,elastic properties,thermo-physical properties,as well as electronic properties of hexa-（Mo,Cr,W）2C carbides were investigated by first-principles *** results indicated that the Mo8C4,Mo7Cr1C4,Mo7W1C4,Mo6W2C4,and Mo6W1Cr1C4 are stable and the stability follows the sequence：Mo6W1Cr1C4〉Mo7W1C4〉Mo7Cr1C4〉 Mo6W2C4〉 ***6W1Cr1C4 shows the highest stability,deformation resistance and hardness.G/B（shear modulus/bulk modulus）and Poisson′s ratio of the stable hexa-（Mo,Cr,W）2C are all larger than 1.75 and 0.26,respectively,which indicates that they are all *** anisotropies are mainly due to the different Vogit shear modulus/Reuss shear modulus;the mechanical anisotropy of Mo7Cr1C4 is the largest,and that of Mo8C4 is the ***,the obtained Debye temperatureΘDand heat capacity Cpindicate that Mo6W2C4 possesses the best thermal conductivity（ΘD=497.72K）,while Mo7Cr1C4 and Mo6W2C4possess the largest heat capacity when the temperature is in the range of 0-10 Kand larger than 10 K,*** the electronic property analysis,the doped Cr and W atoms can not only participate in orbitals hybridization themselves but also enhance the orbitals hybridization between Mo and C atoms,which can reinforce the interatomic interactions.

关键词： hexa (Mo,Cr, W)2C carbide elastic property electronic structure thermo-physical property first-principles calculation

A first-principles study on electronic structures and elastic properties of metal dopedα-Fe(N)high nitrogen steel

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Journal of Iron and Steel Research International 2017年第1期24卷 103-110页

作者： Ji-chun Yang Xiang-jun Liu Gui-xiao Jia Xiao-yang Fu School of Materials and Metallurgy Inner Mongolia University of Science and TechnologyBaotou 014010Inner MongoliaChina

The binding energies,electronic structures and elastic properties of Ti,V,Cr,Mn,Co,Ni and Mg dopedα-Fe（N）systems have been investigated using a first-principles *** calculated results show that the dopings of Ti,V,Cr and Co improve the stability ofα-Fe（N）,and the stability ofα-Fe（N）is slightly weakened by Mn and Ni,and the doping of Mg is *** Ti,V,Cr and Mn dopedα-Fe（N）systems in which the doping metals are on the left side of Fe in the element periodic table andα-Fe（N）systems doped by Co and Ni on the right side of Fe,their corresponding cohesive forces decrease with decreasing atomic radius of the doping *** obvious interaction exists among M3 d,Fe4s3p3d and N2 *** these doping systems,metal atoms lose electrons,while N gains *** of Ti,V,Cr and Mn inα-Fe（N）strengthen the interaction between N and the surrounding metals,and it is not apparent for the dopings of Co,Ni and *** calculations of Fe15 MN systems show that,except for the Fe15 MgN system,shear modulus G and Young modulus E of Fe15 MN systems are improved,and the bulk modulus Bslightly decreases,namely,total elastic properties are *** magnitude change rule of E reflecting the cohesive force between atoms is consistent with that for the binding energies.

关键词： First principle High nitrogen steel Metal nitride Electronic structure elastic property

First-principles investigation of the electronic,elastic and thermodynamic properties of VC under high pressure

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Chinese Physics B 2011年第4期20卷 415-420页

作者：郝爱民周铁军朱岩张新宇刘日平 State Key Laboratory of Metastable Materials Science and Technology Yanshan University College of Physics and Chemistry Hebei Normal University of Science and Technology College of Mathematics and Information Hebei Normal University of Science and Technology

An investigation of the electronic, elastic and thermodynamic properties of VC under high pressure has been conducted using first-principles calculations based on density functional theory （DFT） with the plane-wave basis set, as implemented in the CASTEP code. At elevated pressures, VC is predicted to undergo a structural transition from a relatively open NaCl-type structure to a more dense CsCl,type one. The predicted transition pressure is 520 GPa. The elastic constant, Debye temperature and heat capacity each as a function of pressure and/or temperature of VC are presented for the first time.

关键词： high pressure first-principles calculations elastic property phase transition

Theoretical investigation on the electronic structure,elastic properties, and intrinsic hardness of Si2N20

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Chinese Physics B 2012年第6期21卷 421-430页

作者：丁迎春陈敏高秀英蒋孟衡 College of Optoelectronics Technology Chengdu University of Information TechnologyChengdu 610225China

According to the density functional theory we systematically study the electronic structure, the mechanical prop- erties and the intrinsic hardness of Si2N2O polymorphs using the first-principles method. The elastic constants of four Si2N2O structures are obtained using the stress-strain method. The mechanical moduli （bulk modulus, Young’s mod-ulus, and shear modulus） are evaluated using the Voigt-Reuss-Hill approach. It is found that the tetragonal Si2N2O exhibits a larger mechanical modulus than the other phases. Some empirical methods are used to calculate the Vickers hardnesses of the Si2N2O structures. We further estimate the Vickers hardnesses of the four Si2N2O crystal structures, suggesting all Si2N2O phases are not the superhard compounds. The results imply that the tetragonal Si2N2O is the hardest phase. The hardness of tetragonal Si2N2O is 31.52 GPa which is close to values of β-Si3N4 and γ-Si3N4.

关键词： elastic property Vickers hardness electronic structure

Micromechanics of substrate-supported thin films

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Acta Mechanica Sinica 2018年第2期34卷 381-391页

作者： Wei He Meidong Han Shibin Wang Lin-An Li Xiuli Xue Department of Mechanics Tianjin University Department of Engineering Mechanics Hunan University of Science and Technology

The mechanical properties of metallic thin films deposited on a substrate play a crucial role in the performance of micro/nano-electromechanical systems(MEMS/NEMS)and flexible electronics. This article reviews ongoing study on the mechanics of substrate-supported thin films, with emphasis on the experimental characterization techniques,such as the rule of mixture and X-ray tensile testing. In particular, the determination of interfacial adhesion energy, film deformation, elastic properties and Bauschinger effect are discussed.

关键词： Thin films Deformation Adhesion elastic property Bauschinger effect

Regulation of thermoelastic properties of concave-packaged DNA adsorption films and its relevant microcantilever detection signals

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Acta Mechanica Sinica 2021年第4期37卷 705-711,I0004页

作者： C.X.Wu N.H.Zhang C.Y.Zhang J.Z.Wu School of Mechanics and Engineering Science Shanghai UniversityShanghai 200444China Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai Institute of Applied Mathematics and MechanicsShanghai 200072China

The packing patterns have close correlation with the thermoelastic properties of DNA adsorption films and the relevant detection signals of *** this paper,we investigate the influence of packing patterns on the thermoelastic properties of DNA adsorption films,the detection signals of microcantilevers and their temperature ***,the Parsegian's empirical potential based on a mesoscopic liquid crystal theory is employed to describe the interaction energy among coarse-grained DNA cylinders;then,the thought experiment method and the force balance method of nonlinear elastic network nodes are combined to characterize the elastic modulus,prestress and thermal expansion coefficient of DNA adsorption films;finally,based on an effective macroscopic continuum model for DNA microbeam deformation,we study the microcantilever resonance frequency shifts caused by DNA adsorptions and the temperature effect on the microcantilever static deflections,*** show that,compared with the convex-packaged,the re-entrant honeycomb packing pattern endows DNA adsorption films with a larger adjustable range of the elastic modulus and prestress,so as to make DNA-microcantilevers having an enhanced dynamic detection signal whereas a weaker response to temperature *** results are expected to provide a new option for the regulation design of DNA composite materials and microbeam sensors.

关键词： DNA-microbeam Packaging pattern elastic property Thermal expansion coefficient Detection signal

First-principles calculations of structural,elastic and electronic properties of(TaNb)0.67(HfZrTi)0.33 high-entropy alloy under high pressure

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International Journal of Minerals,Metallurgy and Materials 2020年第10期27卷 1405-1414页

作者： Zhi-sheng Nong Hao-yu Wang Jing-chuan Zhu School of Materials Science and Engineering Shenyang Aerospace UniversityShenyang 110136China School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China

To clarify the effect of pressure on a(TaNb)0.67(HfZrTi)0.33 alloy composed of a solid solution with a single body-centered-cubic crystal structure,we used first-principles calculations to theoretically investigate the structural,elastic,and electronic properties of this alloy at different *** results show that the calculated equilibrium lattice parameters are consistent with the experimental results,and that the normalized structural parameters of lattice constants and volume decrease whereas the total enthalpy differenceΔE and elastic constants increase with increasing ***(TaNb)0.67(HfZrTi)0.33 alloy exhibits mechanical stability at high pressures lower than 400 *** high pressure,the bulk modulus B shows larger values than the shear modulus G,and the alloy exhibits an obvious anisotropic feature at pressures ranging from 30 to 70 *** analysis of the electronic structures reveals that the atomic orbitals are occupied by the electrons change due to the compression of the crystal lattices under the effect of high pressure,which results in a decrease in the total density of states and a wider electron energy *** factor is favorable for zero resistance.

关键词： first-principles calculations elastic property electronic structure density of states high-entropy alloys high pressure

Electronic,thermodynamic and elastic properties of pyrite RuO_2

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Chinese Physics B 2009年第11期18卷 4981-4987页

作者：杨则金郭云东王光昶李劲戴伟刘锦超程新路杨向东 Institute of Atomic and Molecular Physics of Sichuan University School of Physics and Electronic Information Engineering Neijiang Normal University Teaching and Researching Section of Physics Chengdu Medical College College of Material and Chemical Engineering Hainan University Chinese Academy of Engineering Physics

This paper calculates the elastic, thermodynamic and electronic properties of pyrite （Pa^-3） RuO2 by the plane-wave pseudopotential density functional theory （DFT） method. The lattice parameters, normalized elastic constants, Cauchy pressure, brittle-ductile relations, heat capacity and Debye temperature are successfully obtained. The Murnaghan equation of state shows that pyrite RuO2 is a potential superhard material. Internal coordinate parameter increases with pressure, which disagrees with experimental data. An analysis based on electronic structure and the pseudogap reveals that the bonding nature in RuO2 is a combination of covalent, ionic and metallic bonding. A study of the elastic properties indicates that the pyrite phase is isotropic under usual conditions. The relationship between brittleness and ductility shows that pyrite RuO2 behaves in a ductile matter at zero pressure and the degree of ductility increases with pressure.

关键词： elastic property thermodynamic property electronic structure

elastic and Thermo-physical Properties of Stannite-type Cu_2ZnSnS_4 and Cu_2ZnSnSe_4 from First-principles Calculations

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Acta Metallurgica Sinica(English Letters) 2013年第3期26卷 285-292页

作者： Xiancong HE Jinhong PI Yuming DAI Xiaoquan LI Department of Materials Science and Engineering Nanjing Institute of Technology

Cu2ZnSnS4 (CZTS) and Cu2ZnSnSe4 (CZTSe) with optimum band gaps about 1.5 eV are important absorbers for solar cells. The elastic constants and the thermo-physical properties of the stannite-type CZTS and CZTSe are calculated by using density-functional theory (DFT) and the quasi-harmonic Debye model. The bonding strength along the [100] and [010] directions is the same to that along the [001] direction and the shear elastic properties of the {001} plane are anisotropic for CZTS and CZTSe. Both compounds exhibit ductile behavior due to their high ratio of bulk modulus to shear modulus (K/G). The values of thermal capacity are close to 200 J/(mol·K) at above 300 K, and the thermal expansion coefficients decrease with increasing pressure at same temperature. The entropy is variable by power-exponent, and the internal energy is almost linear with increasing temperature for CZTS and CZTSe. The Gibbs energy of CZTS is lower than that of CZTSe under same temperature and pressure. The Debye temperatures are 297 and 232 K, and Grneisen parameters are 2.36 and 2.37 for CZTS and CZTSe at 300 K, respectively.

关键词： elastic property Thermo-physical property First-principles Cu2ZnSnS4 Cu2ZnSnSe4