Anisotropies in Elasticity, Sound Velocity, and Minimum Thermal Conductivity of Low Borides VxBy Compounds

Anisotropies in the elasticity, sound velocity, and minimum thermal conductivity of low borides VB, V5B6, V3B4, and V2B3 are discussed using the first-principles calculations. The various elastic anisotropic indexes (AU, Acomp, and Ashear), three-dimensional (3D) surface contours, and their planar projections among different crystallographic planes of bulk modulus, shear modulus, and Young’s modulus are used to characterize elastic anisotropy. The bulk, shear, and Young’s moduli all show relatively strong degrees of anisotropy. With increased B content, the degree of anisotropy of the bulk modulus increases while those of the shear modulus and Young’s modulus decrease. The anisotropies of the sound velocity in the different planes show obvious differences. Meanwhile, the minimum thermal conductivity shows little dependence on crystallographic direction.

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Electronic, Mechanical and Elastic Anisotropy Properties of X-Diamondyne (X = Si, Ge)

Materials ◽

10.3390/ma12213589 ◽

2019 ◽

Vol 12 (21) ◽

pp. 3589 ◽

Cited By ~ 7

Author(s):

Qingyang Fan ◽

Zhongxing Duan ◽

Yanxing Song ◽

Wei Zhang ◽

Qidong Zhang ◽

...

Keyword(s):

Thermal Conductivity ◽

Shear Modulus ◽

Young’S Modulus ◽

Density Functional ◽

Elastic Anisotropy ◽

Young's Modulus ◽

Wide Band ◽

Band Gaps ◽

Mechanical Anisotropy ◽

Semiconductor Materials

The three-dimensional (3D) diamond-like semiconductor materials Si-diamondyne and Ge-diamondyne (also called SiC4 and GeC4) are studied utilizing density functional theory in this work, where the structural, elastic, electronic and mechanical anisotropy properties along with the minimum thermal conductivity are considered. SiC4 and GeC4 are semiconductor materials with direct band gaps and wide band gaps of 5.02 and 5.60 eV, respectively. The Debye temperatures of diamondyne, Si- and Ge-diamondyne are 422, 385 and 242 K, respectively, utilizing the empirical formula of the elastic modulus. Among these, Si-diamondyne has the largest mechanical anisotropy in the shear modulus and Young’s modulus, and Diamond has the smallest mechanical anisotropy in the Young’s modulus and shear modulus. The mechanical anisotropy in the Young’s modulus and shear modulus of Si-diamondyne is more than three times that of diamond as determined by the characterization of the ratio of the maximum value to the minimum value. The minimum thermal conductivity values of Si- and Ge-diamondyne are 0.727 and 0.524 W cm−1 K−1, respectively, and thus, Si- and Ge-diamondyne may be used in the thermoelectric industry.

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Optical, Electronic Properties and Anisotropy in Mechanical Properties of “X” Type Carbon Allotropes

Materials ◽

10.3390/ma13092079 ◽

2020 ◽

Vol 13 (9) ◽

pp. 2079 ◽

Cited By ~ 5

Author(s):

Jiao Cheng ◽

Qidong Zhang

Keyword(s):

Shear Modulus ◽

Sound Velocity ◽

Young’S Modulus ◽

Debye Temperature ◽

Poisson’S Ratio ◽

Carbon Materials ◽

Elastic Anisotropy ◽

Young's Modulus ◽

Poisson's Ratio ◽

Cubic Symmetry

Based on first-principle calculations, the mechanical anisotropy and the electronic and optical properties of seven kinds of carbon materials are investigated in this work. These seven materials have similar structures: they all have X-type structures, with carbon atoms or carbon clusters at the center and stacking towards the space. A calculation of anisotropy shows that the order of elastic anisotropy in terms of the shear modulus, Young’s modulus and Poisson’s ratio of these seven carbon materials with similar structure is diamond < supercubane < T carbon < Y carbon < TY carbon < cubane-diyne < cubane-yne. As these seven carbon materials exhibit cubic symmetry, Young’s modulus has the same anisotropy in some major planes, so the order of elastic anisotropy in the Young’s modulus of these seven main planes is (111) plane < (001) plane = (010) plane = (100) plane < (011) plane = (110) plane = (101) plane. It is also due to the fact that their crystal structure has cubic symmetry that the elastic anisotropy in the shear modulus and the Poisson’s ratio of these seven carbon materials on the seven major planes are the same. Among the three propagation directions of [100], [110], and [111], the [110] propagation direction’s anisotropic ratio of the sound velocity of TY carbon is the largest, while the anisotropic ratio of the sound velocity of cubane-diyne on the [100] propagation direction is the smallest. In addition, not surprisingly, the diamond has the largest Debye temperature, while the TY carbon has the smallest Debye temperature. Finally, TY carbon, T carbon and cubane-diyne are also potential semiconductor materials for photoelectric applications owing to their higher or similar absorption coefficients to GaAs in the visible region.

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First-Principles Study of Structural, Mechanical, and Thermodynamic Properties of Refractory Metals (Rh, Ir, W, Ta, Nb, Mo, Re, and Os)

Materials Science Forum ◽

10.4028/www.scientific.net/msf.993.1017 ◽

2020 ◽

Vol 993 ◽

pp. 1017-1030

Author(s):

Ying Jie Sun ◽

Kai Xiong ◽

Zong Bo Li ◽

Shun Meng Zhang ◽

Yong Mao

Keyword(s):

Thermodynamic Properties ◽

Shear Modulus ◽

Bulk Modulus ◽

Young’S Modulus ◽

First Principles ◽

Elastic Anisotropy ◽

Young's Modulus ◽

Refractory Metals ◽

Body Centered Cubic ◽

Cubic Metals

The structural, mechanical, and thermodynamic properties of refractory metals Rh, Ir, W, Ta, Nb, Mo, Re, and Os have been systematically investigated by first-principles calculations based on density functional theory. Comparative studies reveal that Young's modulus (E = 636.42 GPa), shear modulus (G = 256.81 GPa), bulk modulus (B = 406.55 GPa), and microhardness (H = 44.69 GPa) of hexagonal Os are the highest, which reveals Os has the best overall mechanical properties. The body-centered cubic Nb has the smallest Young's modulus (E = 94.76 GPa), shear modulus (G = 33.62 GPa), bulk modulus (B = 174.50 GPa), and hardness (H = 2.04 GPa). Based on the ratio of bulk to shear modulus, it is judged that Rh, Ir, and Os are brittle materials (B/G < 1.75), and Nb, Ta, Mo, W, and Re exhibit ductile (B/G > 1.75). The elastic anisotropy has also been discussed by plotting both the 3D contours and the 2D planar projections of Young's modulus. For the face-centered cubic metals Rh and Ir and hexagonal close-packed metals Re and Os, the 3D contours of the Young's modulus are very similar, whereas body-centered cubic metals Ta, W, Nb, and Mo exhibit significant difference in elastic anisotropy. The thermodynamic calculations show that Debye temperature and minimum thermal conductivity decreases along Rh, Os, Mo, Ir, Re, W, Ta, Nb sequence. Furthermore, the results can be used as a general guidance for the design and development of high temperature refractory alloy system.

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Research on Mechanical Properties of High-Pressure Anhydrite Based on First Principles

Crystals ◽

10.3390/cryst10040240 ◽

2020 ◽

Vol 10 (4) ◽

pp. 240

Author(s):

Xianren Zeng ◽

Shihui You ◽

Linmei Li ◽

Zhangli Lai ◽

Guangyan Hu ◽

...

Keyword(s):

Thermal Conductivity ◽

Bulk Modulus ◽

Young’S Modulus ◽

First Principles ◽

Poisson’S Ratio ◽

Young's Modulus ◽

Three Dimensional ◽

Poisson's Ratio ◽

Physical Parameters ◽

Three Dimensional Model

This article focuses on the elucidation of a three-dimensional model of the structure of anhydrite crystal (CaSO4). The structure parameters of anhydrite crystal were obtained by means of first principles after structure optimization at 0~120 MPa. In comparison with previous experimental and theoretical calculation values, the results we obtained are strikingly similar to the previous data. The elastic constants and physical parameters of anhydrite crystal were also studied by the first-principles method. Based on this, we further studied the Young’s modulus and Poisson’s ratio of anhydrite crystal, the anisotropy factor, the speed of sound, the minimum thermal conductivity and the hardness of the material. It was shown that the bulk modulus and Poisson’s ratio of anhydrite crystal rose slowly with increasing pressure. The anisotropy characteristics of the Young’s modulus and shear modulus of anhydrite crystal were consistent under various pressure levels, while the difference in the anisotropy characteristics of the bulk modulus appeared. The acoustic velocities of anhydrite crystal tended to be stable with increasing pressure. The minimum thermal conductivity remained relatively unchanged with increasing pressure. However, the material hardness declined gradually with increasing pressure.

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Mechanical and thermodynamics properties of Al2Ca and Mg2Ca under various pressure: A first principle study

Materials Express ◽

10.1166/mex.2021.2064 ◽

2021 ◽

Vol 11 (9) ◽

pp. 1571-1578

Author(s):

Zai Gao Huang

Keyword(s):

Shear Modulus ◽

Bulk Modulus ◽

Young’S Modulus ◽

Elastic Constants ◽

Coefficient Of Thermal Expansion ◽

Young's Modulus ◽

Structural Parameters ◽

Harmonic Approximation ◽

Polycrystalline Materials ◽

Ductile Phase

The mechanical and thermodynamic properties of Al2Ca and Mg2Ca in the pressure range of 0~100 Gpa were investigated using first-principles calculations. The structural parameters, such as lattice constant ratio, unit cell volume ratio, density, were investigated. The calculated elastic constants satisfy the born’s stability criterion, indicating that they are mechanically stable at normal and high pressure. Mechanical parameters such as bulk modulus, shear modulus, and Young’s modulus of polycrystalline materials have been derived from single-crystal elastic constants. The Poisson’s ratio and anisotropy were investigated. The results show that the B/G value of Mg2Ca is greater than 1.75, indicating it is a ductile phase under various pressures. When the pressure was equal to 40 Gpa, Al2Ca was transferred brittle to toughness, and the bulk modulus, shear modulus, and Young’s modulus of Al2Ca were all larger than those of Mg2Ca, indicating that the comprehensive mechanical properties of Al2Ca are better than those of Mg2Ca. The constant heat capacity obtained by the quasi-harmonic approximation indicates that the ability of Mg2Ca to release or store heat is greater than that of Al2Ca. Moreover, the coefficient of thermal expansion (α) increases exponentially at lower temperatures and linearly at higher temperatures for both alloys.

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Effect of Ce Substitution on Mechanical and Thermal Properties of Tetragonal YSZ: First-Principles Calculations

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1120-1121.73 ◽

2015 ◽

Vol 1120-1121 ◽

pp. 73-84

Author(s):

Lei Jin ◽

Pei Zhong Li ◽

Guo Dong Zhou ◽

Wei Gao ◽

Jiang Ning Ma ◽

...

Keyword(s):

Thermal Conductivity ◽

Thermal Properties ◽

Sound Velocity ◽

Young’S Modulus ◽

Elastic Constants ◽

First Principles ◽

Density Functional ◽

Young's Modulus ◽

Mechanical And Thermal Properties ◽

Ce Substitution

The effect of impurity Ce on the mechanical and thermal properties of tetragonal ZrO2 stabilized by rare earth element Y (YSZ) have been studied using first principles density functional theory within generalized gradient approximation (GGA) for the exchange correlation potential. The predicted elastic constants indicate that YSZ and Ce doped YSZ (CeYSZ) are mechanically stable structures. And then the numerical estimates of bulk modulus, shear modulus, Young’s modulus, Poisson’s ratio, sound velocity and minimum thermal conductivity were performed using the calculated elastic constants and analyzed for the first time. The values of sound velocity from different orientations are also reported. The agreement between the results of the available experiments and our calculations was satisfactory. Our calculated results indicate that Young’s modulus, hardness, mean sound velocity and minimum thermal conductivity of YSZ can be decreased by Ce substitution. The reasons are from the “softened” Ce-O bond strength using bond population and relative volume change under external hydrostatic pressure. Chemical bonding nature was also analyzed from the density of states and electron density difference.

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Lattice dynamical and elastic properties of BaFX (X = Cl, Br and I): Matlockite structure compounds

International Journal of Modern Physics B ◽

10.1142/s0217979219502217 ◽

2019 ◽

Vol 33 (20) ◽

pp. 1950221 ◽

Cited By ~ 1

Author(s):

A. K. Kushwaha ◽

S. Akbudak ◽

A. C. Yadav ◽

Ş. Uğur ◽

G. Uğur

Keyword(s):

Shear Modulus ◽

Bulk Modulus ◽

Young’S Modulus ◽

Elastic Constants ◽

Phonon Mode ◽

Young's Modulus ◽

Nearest Neighbors ◽

Crystallographic Direction ◽

Theoretical Results ◽

Rigid Ion Model

In this study, an eleven-parameter rigid-ion model (RIM) is proposed for BaFX (X = Cl, Br and I) matlockite structure compounds. The interatomic interactions up to fourth nearest neighbors for the studied compounds are calculated. The zone-center raman and infrared phonon mode frequencies, elastic constants, bulk modulus B, shear modulus G, Young’s modulus E, Poisson’s coefficient, Debye temperature and sound velocity along [100], [110] and [001] directions have been calculated. It is observed that the studied BaFCl, BaFBr and BaFI compounds are stiffer in [100] direction than [001] crystallographic direction and the bulk modulus, shear modulus and Young’s modulus of the studied compounds decrease in the order of BaFCl [Formula: see text] BaFBr [Formula: see text] BaFI. The obtained results are compared with the theoretical and experimental results. It is observed that the obtained results agree very well with the experimental and theoretical results available in the literature.

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Elastic and Plastic Anisotropy of Indium

Canadian Journal of Physics ◽

10.1139/p75-172 ◽

1975 ◽

Vol 53 (14) ◽

pp. 1338-1348 ◽

Cited By ~ 5

Author(s):

L. R. Wicks ◽

W. R. Tyson

Keyword(s):

Shear Modulus ◽

Young’S Modulus ◽

Elastic Anisotropy ◽

Young's Modulus ◽

Plastic Anisotropy ◽

Slip Systems ◽

Face Centered ◽

Lattice Friction

The elastic anisotropy of face centered tetragonal indium has been examined with reference to the ratios between selected moduli, Young's modulus, and shear modulus. Elastic energies and lattice friction stresses have been calculated for the likely slip systems and dissociation reactions have been considered. Slip on {111} is favored, being in agreement with experiment.

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Elastic Constants of Magnesium Thorium Alloy

Journal of Basic Engineering ◽

10.1115/1.3609576 ◽

1967 ◽

Vol 89 (1) ◽

pp. 93-97

Author(s):

J. R. Asay

Keyword(s):

Shear Modulus ◽

Bulk Modulus ◽

Young’S Modulus ◽

Poisson’S Ratio ◽

Young's Modulus ◽

Longitudinal Velocity ◽

Shear Velocity ◽

Polycrystalline Sample ◽

Poisson's Ratio ◽

Wave Measurements

The longitudinal and shear wave velocities in a polycrystalline sample of magnesium thorium alloy were measured by a pulse transmission technique as a function of temperature. Temperatures ranged from 25 C to about 350 deg C for longitudinal wave measurements and to about 220 deg C for shear measurements. The resulting velocity data were used to calculate various elastic properties of the material, including Young’s modulus, shear modulus, bulk modulus, and Poisson’s ratio. The resulting least squares fits for these data are: Longitudinal velocity, cl = 5.749 − 3.987 × 10−4T − 1.139 × 10−6T2mm/μsec; shear velocity, ct = 3.108 − 1.421 × 10−4T − 2.588 × 10−6T2mm/μsec; bulk modulus, B = 3.576 × 10″ − 2.744 × 107T + 1.187 × 105T2 dynes/cm2; Young’s modulus, E = 4.435 × 10″ − 1.415 × 107T = 6.037 × 105T2 dynes/cm2; shear modulus, G = 1.716 × 10″ − 7.994 × 106T − 2.619 × 105T2 dynes/cm2; Poisson’s ratio, σ = 0.293 − 6.459 × 10−6T + 3.392 × 10−7T2.

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