scholarly journals Ab Initio Study of Ternary W5Si3 Type TM5Sn2X Compounds (TM = Nb, Ti and X = Al, Si)

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3217 ◽  
Author(s):  
Ioannis Papadimitriou ◽  
Claire Utton ◽  
Panos Tsakiropoulos
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Elastic Moduli ◽  
Harmonic Approximation ◽  
Wave Method ◽  
Ab Initio Study ◽  
Functional Theory ◽  
Plane Wave Method ◽  
Ternary Compounds ◽  
The Enthalpy Of Formation

The adhesion of the scale formed on Nb-silicide based alloys at 1473 K improves when Al and Sn are in synergy with Si and Ti. This improvement is observed when there is segregation of Sn in the microstructure below the alloy/scale interface and a layer rich in intermetallics that include TM5Sn2X compounds is formed at the interface. Data for the ternary compounds is scarce. In this paper elastic and thermodynamic properties of the Nb5Sn2Al, Ti5Sn2Si, Ti5Sn2Al and Nb5Sn2Si compounds were studied using the first-principles, pseudopotential plane-wave method based on density functional theory. The enthalpy of formation of the ternary intermetallics was calculated using the quasi-harmonic approximation. The calculations suggest that the Nb5Sn2Si is the stiffest; that the Nb5Sn2Al and Ti5Sn2Si are the most and less ductile phases respectively; and that Nb significantly increases the bulk, shear and elastic moduli of the ternary compound compared with Ti.

FIRST-PRINCIPLES STUDY ON β-SiC/BNNT CORE/SHELL NANOCABLE

2013 ◽  
Vol 27 (23) ◽  
pp. 1350169
Author(s):  
X. C. ZOU ◽  
J. OUYANG ◽  
M. S. WU ◽  
G. LIU ◽  
X. L. LEI ◽  
...  
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Boron Nitride Nanotubes ◽  
Core Shell ◽  
Wave Method ◽  
Functional Theory ◽  
Plane Wave Method ◽  
Sic Nanowires ◽  
Structural And Electronic Properties ◽  
Cubic Silicon Carbide

In this paper, we studied the structural and electronic properties of core/shell nanocables composed of cubic silicon carbide nanowires (β- SiCNW ) and boron nitride nanotubes (BNNT) using first-principles pseudopotential plane wave method within density functional theory. Our results show that the β- SiC /BNNT heterojunction structures are metallic, which primarily originates from the contributions of the BNNTs and the surfaces of SiCNW s. The BNNTs exhibit metallic characters after the SiC nanowires are inserted. The transition of the BNNTs is attributed to the charge transfer between BNNTs and SiCNW s.

Structural and Elastic Properties of AlAs under Pressure from First-Principles Calculations

2011 ◽  
Vol 403-408 ◽  
pp. 84-87 ◽  
Author(s):  
Hong Ling Cui ◽  
Shi Jie Lv ◽  
Li Ben Li ◽  
Guang Fu Ji
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Wave Method ◽  
First Principles Calculations ◽  
Elastic Parameters ◽  
Pressure Derivative ◽  
Functional Theory ◽  
Plane Wave Method ◽  
Zinc Blende ◽  
The Density Functional Theory

A first-principles plane wave method with the ultrasoft pseudopotential scheme in the frame of the density functional theory (DFT) is performed to calculate the structural and lattice parameters, the bulk modulus B0 and its pressure derivative B0' of the zinc-blende AlAs, rocksalt AlAs and NiAs-AlAs. The elastic parameters of the zinc-blende AlAs, rocksalt AlAs and NiAs- AlAs were calculated. We also calculate the phase transition pressures between different phases. Our results are satisfactory. Our results are consistent with other results.

First-Principles Calculation of Elastic Properties of TiB2 and ZrB2

2010 ◽  
Vol 150-151 ◽  
pp. 40-43 ◽  
Author(s):  
H.Y. Wang ◽  
F.Y. Xue ◽  
Nai Hui Zhao ◽  
De Jun Li
Keyword(s):  
Density Functional Theory ◽  
Elastic Modulus ◽  
Elastic Properties ◽  
First Principles ◽  
Electronic Structures ◽  
Density Functional ◽  
First Principles Calculation ◽  
Wave Method ◽  
Functional Theory ◽  
Plane Wave Method

Based on Density Functional Theory (DFT), using first-principles pseudopotential plane wave method, elastic properties and electronic structure of TiB2 and ZrB2 were calculated. The elastic constants of these compounds were calculated by Voigt-Reuss-Hill method. The results show that the elastic modulus of TiB2 and ZrB2 are 594 and 520 GPa, and the shear modulus are 268 and 229 GPa, respectively. Pugh empirical criterion and Poisson's ratio show that the two compounds are very brittle, and the brittleness of TiB2 is higher than ZrB2. Finally, the differences in elastic properties between TiB2 and ZrB2 result form their electronic structures.

Thermodynamic Properties of CaSiO3 Perovskite at High Pressure and High Temperature

2009 ◽  
Vol 64 (5-6) ◽  
pp. 399-404 ◽  
Author(s):  
Zi-Jiang Liu ◽  
Xiao-Ming Tan ◽  
Yuan Guo ◽  
Xiao-Ping Zheng ◽  
Wen-Zhao Wu
Keyword(s):  
Thermodynamic Properties ◽  
First Principles ◽  
Density Functional ◽  
High Pressures ◽  
Local Density ◽  
Harmonic Approximation ◽  
Debye Model ◽  
Functional Theory ◽  
Casio3 Perovskite ◽  
First Time

The thermodynamic properties of tetragonal CaSiO3 perovskite are predicted at high pressures and temperatures using the Debye model for the first time. This model combines the ab initio calculations within local density approximation using pseudopotentials and a plane wave basis in the framework of density functional theory, and it takes into account the phononic effects within the quasi-harmonic approximation. It is found that the calculated equation of state is in excellent agreement with the observed values at ambient condition. Based on the first-principles study and the Debye model, the thermal properties including the Debye temperature, the heat capacity, the thermal expansion and the entropy are obtained in the whole pressure range from 0 to 150 GPa and temperature range from 0 to 2000 K.

THERMODYNAMIC PROPERTIES OF MgSiO3 POST-PEROVSKITE

2010 ◽  
Vol 24 (03) ◽  
pp. 315-324
Author(s):  
ZI-JIANG LIU ◽  
XIAO-WEI SUN ◽  
CAI-RONG ZHANG ◽  
LI-NA TIAN ◽  
YUAN GUO
Keyword(s):  
Thermodynamic Properties ◽  
First Principles ◽  
Density Functional ◽  
High Pressures ◽  
Local Density ◽  
Harmonic Approximation ◽  
Debye Model ◽  
Functional Theory ◽  
High Pressures And Temperatures ◽  
First Time

The thermodynamic properties of MgSiO 3 post-perovskite are predicted at high pressures and temperatures using the Debye model for the first time. This model combines with ab initio calculations within local density approximation using pseudopotentials and a plane wave basis in the framework of density functional theory, and it takes into account the phononic effects within the quasi-harmonic approximation. It is found that the calculated equation of state of MgSiO 3 post-perovskite is in excellent agreement with the latest observed values. Based on the first-principles study and the Debye model, the thermal properties including the Debye temperature, the heat capacity, the thermal expansion, and the entropy are obtained in the whole pressure range from 0 to 150 GPa and temperature range from 0 to 2000 K.

First-principles study of the structural and elastic properties of Ti5Si3 with substitutions Zr, V, Nb, and Cr

2010 ◽  
Vol 25 (12) ◽  
pp. 2317-2324 ◽  
Author(s):  
Hui-Yuan Wang ◽  
Wen-Ping Si ◽  
Shi-Long Li ◽  
Nan Zhang ◽  
Qi-Chuan Jiang
Keyword(s):  
Density Functional Theory ◽  
Elastic Properties ◽  
First Principles ◽  
Electronic Structures ◽  
Density Functional ◽  
Elastic Moduli ◽  
Site Occupancy ◽  
Formation Enthalpy ◽  
Functional Theory ◽  
The Density Functional Theory

The formation enthalpy, electronic structures, and elastic moduli of the intermetallic compound Ti5Si3 with substitutions Zr, V, Nb, and Cr are investigated by using first-principles methods based on the density-functional theory. Our calculation shows that the site occupancy behaviors of alloying elements in Ti5Si3, determined by their atom radius, are consistent with the available experimental observations. Furthermore, using the Voigt–Reuss–Hill (VRH) approximation method, we obtained the bulk modulus B, shear modulus G, and the Young’s modulus E. Among these four substitutions, the V, Nb, and Cr substitutions can improve the ductility of Ti5Si3 effectively, while Zr substitution has little effect on the elastic properties of Ti5Si3. The elastic property variations of Ti5Si3 due to different substitutions are found to be correlated with the Me4d–Me4d antibonding and the strengthened Me4d–Si bonding in the solids.

Ab initio study of hydrogen chemisorption in nitrogen-doped carbon nanotubes

2016 ◽  
Vol 18 (36) ◽  
pp. 25663-25670 ◽  
Author(s):  
Julian David Correa ◽  
Elizabeth Florez ◽  
Miguel Eduardo Mora-Ramos
Keyword(s):  
Carbon Nanotubes ◽  
First Principles ◽  
Density Functional ◽  
Periodic Boundary ◽  
Periodic Boundary Conditions ◽  
Hydrogen Chemisorption ◽  
Ab Initio Study ◽  
Functional Theory ◽  
Nitrogen Doped ◽  
Nitrogen Doped Carbon

The electronic structure of single walled nitrogen-doped carbon nanotubes is calculated by first principles using density functional theory within the supercell approach with periodic boundary conditions.

First-Principles Study on Electronic Structure, Elasticity, Debye Temperature and Anisotropy of Cubic KCaF3

2020 ◽  
Vol 999 ◽  
pp. 109-116
Author(s):  
Xing Liu ◽  
Jia Fu ◽  
Man Man Han ◽  
Kai Xin Sun ◽  
Sheng Li Wei
Keyword(s):  
Electronic Structure ◽  
Debye Temperature ◽  
First Principles ◽  
Density Functional ◽  
Elastic Moduli ◽  
Poisson Ratio ◽  
Structural Parameters ◽  
Functional Material ◽  
Covalent Bonds ◽  
Functional Theory

As a potential functional material in the perovskite family, the KCaF3 on electronic structure, elasticity, Debye temperature and anisotropy are studied based on density functional theory (DFT). Above all, the structural parameters of KCaF3 crystal are optimized. Then the elastic constants and Debye temperature are calculated. The results show that: (1) KCaF3 is composed of covalent bonds, in which the Ca-F bond is stronger than K-F. (2) Ca atom mainly contributes for the electronic properties of KCaF3. (3) The structural parameters of KCaF3 is in fair agreement with the experimental data. (4) The anisotropy of KCaF3 was analyzed from the pure and quasi waves, of which the longitudinal wave velocity in the direction of [100] is the larger than the others two directions ([110] and [111]). Finally, The homogenized elastic moduli (bulk modulus B, shear modulus G, Young's modulus E), Pugh and Poisson ratio, are obtained. This research is meaningful and thus to provides a good theoretical guidance for the design the new ABX3-type material with better performance.

A first principles study of the mechanical properties of Li–Sn alloys

RSC Advances ◽  
2015 ◽  
Vol 5 (45) ◽  
pp. 36022-36029 ◽  
Author(s):  
Panpan Zhang ◽  
Zengsheng Ma ◽  
Yan Wang ◽  
Youlan Zou ◽  
Weixin Lei ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Density Functional Theory ◽  
Failure Mechanism ◽  
First Principles ◽  
Density Functional ◽  
Elastic Moduli ◽  
Poisson's Ratio ◽  
Active Materials ◽  
Functional Theory ◽  
First Principles Study

Focusing on the failure mechanism of active materials during charging–discharging, the mechanical properties of Li–Sn alloys are studied by density functional theory, including elastic moduli, Poisson's ratio, anisotropy, and brittleness-ductility.

Research on the Elastic Property of Three New Superhard Materials

2013 ◽  
Vol 302 ◽  
pp. 165-169
Author(s):  
Feng Li ◽  
Qun Hui ◽  
Jing Ao ◽  
Jin Wang ◽  
Chun Mei Li ◽  
...  
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Local Density ◽  
Correlation Effect ◽  
Superhard Materials ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Spatial Anisotropy ◽  
Plane Wave Method ◽  
Exchange Correlation

In this thesis, elastic properties of three BCN superhard materials with different structures are computed by using CASTEP software developed according to the first principles which are based on density functional theory (DFT) and plane wave method. CA-PZ of local density approximation (LDA) and PBE of generalized gradient approximation (GGA) are adopted to describe the exchange-correlation effect between electrons. The results are compared with other findings and c-BN data. Through analysis, it is found that the spatial anisotropy do exist in the Young's modulus of single crystals all three BCN compounds.

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