Prediction on structural, mechanical and thermal properties of Al4SiC4, Al4C3 and 4H-SiC under high pressure by first-principles calculation

2017 ◽  
Vol 31 (09) ◽  
pp. 1750080 ◽  
Author(s):  
Liang Sun ◽  
Yimin Gao ◽  
Katsumi Yoshida ◽  
Toyohiko Yano ◽  
Wen Wang
Keyword(s):  
Thermal Properties ◽  
First Principles ◽  
Elastic Moduli ◽  
Theoretical Study ◽  
Lattice Parameter ◽  
First Principles Calculation ◽  
Mechanical And Thermal Properties ◽  
Text Data ◽  
Cell Structures ◽  
Higher Temperature

A theoretical study is conducted by first-principles theory to study the structural, electronic, elastic and thermal properties of Al4SiC4, Al4C3 and 4H-SiC phases under pressure. The calculated results indicated that the volumetric shrinkage of Al4SiC4 declines to 16% compared with 4H-SiC for 12% and its length of lattice parameter along c-axis decreases faster than that of along other axes in cell structures. The mechanical properties of Al4SiC4 like elastic constants and elastic moduli increase continuously under pressure. The thermal expansion coefficient of three compounds under pressure are studied first. When temperature is lower than 500 K, the coefficient increases rapidly first then gradually tends to a linear accession at higher temperature and the propensity of increment becomes moderate. The [Formula: see text] data decreases slightly with pressure but increases dramatically with temperature for all compounds.

scholarly journals Strain Conditions for the Inverse Heusler Type Fully Compensated Spin-Gapless Semiconductor Ti2MnAl: A First-Principles Study

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2091 ◽  
Author(s):  
Tie Yang ◽  
Liyu Hao ◽  
Rabah Khenata ◽  
Xiaotian Wang
Keyword(s):  
Thermodynamic Properties ◽  
First Principles ◽  
Density Functional ◽  
Theoretical Study ◽  
Debye Model ◽  
Pressure Effects ◽  
First Principles Calculation ◽  
Strain Condition ◽  
Functional Theory ◽  
Future Work

In this work, we systematically studied the structural, electronic, magnetic, mechanical and thermodynamic properties of the fully compensated spin-gapless inverse Heusler Ti2MnAl compound under pressure strain condition by applying the first-principles calculation based on density functional theory and the quasi-harmonic Debye model. The obtained structural, electronic and magnetic behaviors without pressure are well consistent with previous studies. It is found that the spin-gapless characteristic is destroyed at 20 GPa and then restored with further increase in pressure. While, the fully compensated ferromagnetism shows a better resistance against the pressure up to 30 GPa and then becomes to non-magnetism at higher pressure. Tetragonal distortion has also been investigated and it is found the spin-gapless property is only destroyed when c/a is less than 1 at 95% volume. Three independent elastic constants and various moduli have been calculated and they all show increasing tendency with pressure increase. Additionally, the pressure effects on the thermodynamic properties under different temperature have been studied, including the normalized volume, thermal expansion coefficient, heat capacity at constant volume, Grüneisen constant and Debye temperature. Overall, this theoretical study presents a detailed analysis of the physical properties’ variation under strain condition from different aspects on Ti2MnAl and, thus, can provide a helpful reference for the future work and even inspire some new studies and lead to some insight on the application of this material.

scholarly journals First-Principles Calculations of High-Pressure Physical Properties of Ti0.5Ta0.5 Alloy

Symmetry ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 796
Author(s):  
Fang Yu ◽  
Yu Liu
Keyword(s):  
High Pressure ◽  
Physical Properties ◽  
First Principles ◽  
Theoretical Study ◽  
Applied Pressure ◽  
Lattice Parameter ◽  
Physical Parameters ◽  
First Principles Calculations ◽  
Analysis Method ◽  
Metallic Bond

In this paper, an in-depth theoretical study on some physical properties of Ti0.5Ta0.5 alloy with systematic symmetry under high pressure is conducted via first-principles calculations, and relevant physical parameters are calculated. The results demonstrate that the calculated parameters, including lattice parameter, elastic constants, and elastic moduli, fit well with available theoretical and experimental data when the Ti0.5Ta0.5 alloy is under T = 0 and P = 0 , indicating that the theoretical analysis method can effectively predict the physical properties of the Ti0.5Ta0.5 alloy. The microstructure and macroscopic physical properties of the alloy cannot be destroyed as the applied pressure ranges from 0 to 50GPa, but the phase transition of crystal structure may occur in the Ti0.5Ta0.5 alloy if the applied pressure continues to increase according to the TDOS curves and charge density diagram. The value of Young’s and shear modulus is maximized at P = 25   GPa . The anisotropy factors A ( 100 ) [ 001 ] and A ( 110 ) [ 001 ] are equal to 1, suggesting the Ti0.5Ta0.5 alloy is an isotropic material at 28 GPa, and the metallic bond is strengthened under high pressure. The present results provide helpful insights into the physical properties of Ti0.5Ta0.5 alloy.

Mechanical Properties and Size Effects of ZnO Nanowires Studied by First-Principles Calculation

2010 ◽  
Vol 654-656 ◽  
pp. 1670-1673
Author(s):  
Zhan Jun Gao ◽  
You Song Gu ◽  
Yue Zhang
Keyword(s):  
Mechanical Properties ◽  
First Principles ◽  
Size Effects ◽  
Density Functional ◽  
Elastic Moduli ◽  
Axial Direction ◽  
Zno Nanowires ◽  
First Principles Calculation ◽  
Different Diameters ◽  
Ground State Energies

First-principles density functional calculations were performed to investigate mechanical properties of ZnO nanowires and the size effects. Structural optimizations were performed first, and a series of strains were applied to the nanowires in the axial direction. The ground state energies were calculated and the elastic moduli of ZnO nanowires were obtained from the energy versus strain curves. It is found that the elastic moduli of the ZnO nanowires with three different diameters (1.2, 1.5 and 1.8nm) are 136.3, 138.7 and 138.0 GPa, respectively, and that of bulk ZnO along [0001] direction is 140.1 GPa. The elastic modulus of ZnO nanowire is slightly lower than that of the bulk and it decreases as the diameter decreases. Comparisons to experimental results and theoretical predications are made.

Sign in / Sign up

Export Citation Format

Share Document