The structural, electronic, elastic and thermodynamic properties of V2AX (A = B, Al, Ga, In and TI; X = C and N): A DFT calculation

2019 ◽  
Vol 33 (30) ◽  
pp. 1950359
Author(s):  
Chunying Zuo ◽  
Baishu Chen ◽  
Cheng Zhong ◽  
Jianhua Zhao
Keyword(s):  
Thermodynamic Properties ◽  
Shear Modulus ◽  
Mechanical Stability ◽  
Phonon Dispersion ◽  
Shape Change ◽  
Theoretical Data ◽  
Total Density ◽  
Barrier Coating ◽  
Machinability Index ◽  
Experimental Values

The structural, electronic, elastic and thermodynamic properties of [Formula: see text] ([Formula: see text], Al, Ga, In and TI; [Formula: see text] and N) phase have been systematically investigated by the first principles. The optimized lattice parameters are in good agreement with the experimental values and better than the available theoretical data. We calculated the elastic constants [Formula: see text] and the total density of states, which verified mechanical stability and electronic structural stability, respectively. The other elastic parameters including bulk modulus, shear modulus, Young’s modulus, Cauchy pressure, shear anisotropy factor, linear compressibility coefficients, Pugh’s ratio, Poissons’s ratio, microhardness parameter and machinability index are calculated and discussed in this work. The results show that the compounds we studied are stable in mechanics and are anisotropic materials; the compressibility along [Formula: see text]-axis is lower than that along [Formula: see text]-direction except for [Formula: see text] ([Formula: see text] and N); the compounds of [Formula: see text] ([Formula: see text]) and [Formula: see text] ([Formula: see text]) are brittle in nature, and [Formula: see text] and V2TIN are ductile in nature; the shear modulus [Formula: see text] limits the mechanical stability of the materials under consideration; the ability to resist shape change and the stiffness of [Formula: see text] are stronger compared with [Formula: see text] when A takes B, Al, Ga, In, TI, respectively. Finally we have estimated the Vickers hardness which shows that the hardness of the [Formula: see text] ([Formula: see text], Al, Ga, In, TI) would decrease when C is replaced by N. At last, we investigated the thermodynamic properties of [Formula: see text] by calculating the phonon dispersion, Debye temperature and minimum thermal conductivity. The results show that all structures are dynamical stable and the compounds of [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] are candidates for thermal barrier coating (TBC) materials.

Mechanical and thermodynamic properties of AlX (X = N, P, As) compounds

2017 ◽  
Vol 31 (23) ◽  
pp. 1750167 ◽  
Author(s):  
Lifang Xu ◽  
Wei Bu
Keyword(s):  
Thermodynamic Properties ◽  
Specific Heat ◽  
Atomic Number ◽  
Phonon Dispersion ◽  
Theoretical Data ◽  
Constant Volume ◽  
Vibrational Entropy ◽  
Debye Temperatures ◽  
The Difference ◽  
Good Agreement

The Vickers hardness of various AlX (X = N, P, As) compound polymorphs were calculated with the bond resistance model. Thermodynamic properties, such as vibrational entropy, constant volume specific heat and Debye temperatures, were calculated using phonon dispersion relations and phonon density of states (DOS). The calculated values are in good agreement with the previous experimental and theoretical data. For the same structure of AlX (X = N, P, As) compounds, their hardness and Debye temperatures both decrease with the X atomic number. The wurtzite (wz) and zincblende (zb) structures of the same compounds AlX share an almost identical hardness, but have different Debye temperatures. The difference between wz and zb structures increases as the atomic number of X increases. The thermodynamic properties reveal that the constant volume specific heat approaches the Dulong–Petit rule at high temperatures.

The structures, phase transition and elastic and thermodynamic properties of ZnS from first-principles calculations

2021 ◽  
pp. 2150143
Author(s):  
Bo Li ◽  
Weiyi Ren
Keyword(s):  
Phase Transition ◽  
Thermodynamic Properties ◽  
Bulk Modulus ◽  
First Principles ◽  
Density Functional ◽  
Mechanical Stability ◽  
Theoretical Data ◽  
Debye Model ◽  
Volume Curve ◽  
Temperature And Pressure

The phase transition of zinc sulfide (ZnS) from Zinc-blende (ZB) to a rocksalt (RS) structure and the elastic, thermodynamic properties of the two structures under high temperature and pressure are investigated by first-principles study based on the pseudo-potential plane-wave density functional theory (DFT) combined with the quasi-harmonic Debye model. The lattice constant [Formula: see text], bulk modulus [Formula: see text] and the pressure derivative of bulk modulus [Formula: see text]’ of the two structures are calculated. The results are in good agreement with experimental results and the other theoretical data. From the energy–volume curve, enthalpy equal principle and mechanical stability criterion, the transition pressures from the ZB to the RS structure are 16.83, 16.96 and 16.61 GPa, respectively. The three results and the experimental values 14.7–18.1, 16 GPa are very close to each other. Then the elastic properties are also calculated under the pressure ranging from 0 to 30 GPa. Finally, through the quasi-harmonic Debye model, the thermodynamic properties dependence of temperature and pressure in the ranges between 0–1600 K and 0–30 GPa are obtained successfully.

The structure, elastic and thermodynamic properties of Ti2GaC from first-principles calculation

2019 ◽  
Vol 33 (06) ◽  
pp. 1950030 ◽  
Author(s):  
Xiao-Xia Pu ◽  
Xiao-Jiang Long ◽  
Lin Zhang ◽  
Jun Zhu
Keyword(s):  
Thermodynamic Properties ◽  
Elastic Constant ◽  
Bulk Modulus ◽  
Elastic Constants ◽  
First Principles ◽  
Density Functional ◽  
Mechanical Stability ◽  
Theoretical Data ◽  
Debye Model ◽  
First Principles Calculation

In this work, the structure, elastic and thermodynamic properties of Ti2GaC at high pressure (P) and high-temperature (T) are studied based on the density functional first-principles. The lattice parameters and elastic constants are well consistent with some theoretical data and experimental results. The elastic constant of Ti2GaC increase monotonously with the increase of pressure (P), which demonstrates the mechanical stability of Ti2GaC at the pressure (P) from 0 to 200 GPa. Mechanical properties including Poisson’s ratio ([Formula: see text]), Young’s modulus (E), shear modulus (G) and bulk modulus (B), which are obtained from elastic constants C[Formula: see text]. The ratio B/G value shows that Ti2GaC is a brittle material, but its enhancing ductility significantly with the elevate of pressure (P). The Grüneisen parameters ([Formula: see text]), thermal expansion coefficient ([Formula: see text]), heat capacity (C[Formula: see text]), elastic constant (C[Formula: see text]), bulk modulus (B), energy (E) and volume (V) with the change of temperature (T) or pressure (P) are calculated within the quasi-harmonic Debye model for pressure (P) and temperatures (T) range in 1600 K and 100 GPa. Besides, densities of states and energy band are also obtained and analyzed in comparison with available theoretical data.

Anharmonic perturbation theory to 0(λ4): Equation of state for Kr from the Aziz potential

1992 ◽  
Vol 70 (1) ◽  
pp. 31-39 ◽  
Author(s):  
Ramesh C. Shukla ◽  
Hermann Hübschle
Keyword(s):  
Perturbation Theory ◽  
Thermodynamic Properties ◽  
Potential Function ◽  
Phonon Dispersion ◽  
Perturbation Expansion ◽  
Lattice Parameter ◽  
Thermodynamic Quantities ◽  
Specific Heats ◽  
Experimental Values ◽  
Good Agreement

We carry out a complete calculation of the thermodynamic properties of Kr from a potential function, the Aziz potential, including the three-body Axilrod–Teller contribution, and the (λ4) anharmonic perturbation theory proposed by Shukla and Cowley (Phys. Rev. B: Solid State, 3, 4055 (1971)), where λ is the Van Hove ordering parameter. Along with the λ4 results, in the high-temperature (HT) limit (T > θD, where θD is the Debye temperature), we also present the results for the quasi-harmonic (QH) theory (calculated for all temperatures), the lowest order (λ2) perturbation theory (PT), as well as results from those theories that involve a subset of diagrams (contributions) of 0(λ4), both in the HT limit. This work represents the first calculation of the thermodynamic properties of Kr with the λ2 and λ4 anharmonic PT from a potential function not fitted to the crystal data. The Aziz potential gives an excellent description of phonon-dispersion curves in the three principal symmetry directions. The QH results are in good agreement with the experimental values for most of the thermodynamic quantities for temperatures up to <Tm/3 (Tm is the melting temperature) except for the isothermal bulk modulus (BT) where the agreement is poor in 0 K < T < 25 K and good up to 2Tm/3. The λ2 PT results are only slightly better than the corresponding QH results in the temperature range of < Tm/2. The inclusion of the λ4 PT enhances the results for the Aziz potential significantly. The calculated lattice parameter (a0) is in excellent agreement with experimental values up to 3Tm/4. For T > 3Tm/4, a0 rises rapidly and there is an indication of the breakdown of the perturbation expansion. The values for specific heats at constant volume (Cv) and constant pressure (Cp) and volume expansion (β) are in very good agreement with experiment up to 60% of Tm. The other schemes (with the exception of Ladder) that utilize a subset of diagrams of 0(λ4), which were so successful for the model of a Lennard–Jones solid (viz., ISC (improved self-consistent), λ4-Ladder etc.), are not so useful for this potential. This is due to the heavy cancellation of diagrams in these sets. The ring diagram scheme proposed here for the Aziz potential gives better results than the ISC scheme.

Physical properties of osmium dinitride with fluorite, pyrite, marcasite, and monoclinic structures under high pressure: First-principles study

2015 ◽  
Vol 93 (4) ◽  
pp. 424-433 ◽  
Author(s):  
Ni-Na Ge ◽  
Yong-Kai Wei ◽  
Jia-Jin Tan ◽  
Guang-Fu Ji ◽  
Yan Cheng
Keyword(s):  
Phase Transition ◽  
Thermodynamic Properties ◽  
Sound Velocity ◽  
First Principles ◽  
Mechanical Stability ◽  
Elastic Anisotropy ◽  
Fluorite Structure ◽  
Mechanical Anisotropy ◽  
Total Density ◽  
Structure Phase Transition

The structure, phase transition, elastic, and thermodynamic properties of OsN2 have been studied via first-principles calculations. It is shown that the CoSb2 structure is more stable than other structures. By the calculated H-P relations at 0 K, we found that the phase transition of OsN2 from CoSb2 structure to marcasite structure (ε → δ) occurs at 16.8 GPa, while the phase transition pressure between pyrite structure and fluorite structure (γ → α) is 80 GPa. The results of obtained phase transitions are also confirmed by bond length, sound velocity, and thermal expansion coefficient under different pressures. The pressure dependences of the elastic constants, mechanical stability, and mechanical anisotropy of four structures of OsN2 have been investigated by finding that the fluorite (pyrite and marcasite) structure OsN2 is mechanically stable under hydrostatic pressure (up to 60 GPa). However, the monoclinic structure is mechanically unstable under pressure from 0 to 60 Gpa. The calculated elastic anisotropic factors show that OsN2 possesses high elastic anisotropy under pressure. Moreover, the calculations on total density of states show that OsN2 of different structures has a metallic character, in agreement with previous theoretical results. The thermodynamic properties and sound velocity under diverse pressures of OsN2 of the four structures have been also investigated successfully.

scholarly journals Pressure effect of the mechanical, electronics and thermodynamic properties of Mg–B compounds A first-principles investigations

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
GuoWei Zhang ◽  
Chao Xu ◽  
MingJie Wang ◽  
Ying Dong ◽  
FengEr Sun ◽  
...  
Keyword(s):  
Thermodynamic Properties ◽  
First Principles ◽  
Boron Content ◽  
Structural Parameters ◽  
Debye Model ◽  
Total Density ◽  
First Principle ◽  
Volume Deformation ◽  
Temperature And Pressure ◽  
Total Density Of States

AbstractFirst principle calculations were performed to investigate the structural, mechanical, electronic properties, and thermodynamic properties of three binary Mg–B compounds under pressure, by using the first principle method. The results implied that the structural parameters and the mechanical properties of the Mg–B compounds without pressure are well matched with the obtainable theoretically simulated values and experimental data. The obtained pressure–volume and energy–volume revealed that the three Mg–B compounds were mechanically stable, and the volume variation decreases with an increase in the boron content. The shear and volume deformation resistance indicated that the elastic constant Cij and bulk modulus B increased when the pressure increased up to 40 GPa, and that MgB7 had the strongest capacity to resist shear and volume deformation at zero pressure, which indicated the highest hardness. Meanwhile, MgB4 exhibited a ductility transformation behaviour at 30 GPa, and MgB2 and MgB7 displayed a brittle nature under all the considered pressure conditions. The anisotropy of the three Mg–B compounds under pressure were arranged as follows: MgB4 > MgB2 > MgB7. Moreover, the total density of states varied slightly and decreased with an increase in the pressure. The Debye temperature ΘD of the Mg–B compounds gradually increased with an increase in the pressure and the boron content. The temperature and pressure dependence of the heat capacity and the thermal expansion coefficient α were both obtained on the basis of Debye model under increased pressure from 0 to 40 GPa and increased temperatures. This paper brings a convenient understanding of the magnesium–boron alloys.

scholarly journals Novel structural phases and the properties of LaX (X = P, As) under high pressure: first-principles study

RSC Advances ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 3058-3070
Author(s):  
Yu Zhou ◽  
Lan-Ting Shi ◽  
A-Kun Liang ◽  
Zhao-Yi Zeng ◽  
Xiang-Rong Chen ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Thermodynamic Properties ◽  
First Principles ◽  
Electronic Structures ◽  
Pressure Range ◽  
Mechanical Stability ◽  
First Principles Study

The structures, phase transition, mechanical stability, electronic structures, and thermodynamic properties of lanthanide phosphates (LaP and LaAs) are studied in the pressure range of 0 to 100 GPa by first principles.

Theoretical Investigations on Mechanical Stability and Electronic Structure of NbN under Pressures

2011 ◽  
Vol 90-93 ◽  
pp. 1264-1271
Author(s):  
Xiao Feng Li ◽  
Jun Yi Du
Keyword(s):  
Debye Temperature ◽  
Density Functional ◽  
Mechanical Stability ◽  
Structural Parameters ◽  
Theoretical Data ◽  
Hexagonal Structure ◽  
Functional Theory ◽  
Theoretical Investigations ◽  
Crystallographic Structures ◽  
Good Agreement

The ground structure, elastic and electronic properties of several phases of NbN are determined based on ab initio total-energy calculations within the framework of density functional theory. Among the five crystallographic structures that have been investigated, the hexagonal phases have been found to be more stable than the cubic ones. The calculated equilibrium structural parameters are in good agreement with the available experimental results. The elastic constants of five structures in NbN are calculated, which are in consistent with the obtained theoretical and experimental data. The corresponding Debye temperature and elastic ansitropies are also obtained. The Debye temperature of NbN in various structures consistent with available experimental and theoretical data, in which the Debye temperature of δ-NbN is highest. The anisotropies of ZB-NbN, NaCl-NbN, CsCl-NbN gradually increases. For hexagonal structure, the anisotropies of ε-NbN are stronger than that of δ-NbN. The electronic structures of NbN under pressure are investigated. It is found that NbN have metallization and the hybridizations of atoms in NbN under pressure become stronger.

Structural, elastic and thermodynamic properties of A15-type compounds V3X (X = Ir, Pt and Au) from first-principles calculations

2016 ◽  
Vol 30 (35) ◽  
pp. 1650414 ◽  
Author(s):  
Mingliang Wang ◽  
Zhe Chen ◽  
Dong Chen ◽  
Cunjuan Xia ◽  
Yi Wu
Keyword(s):  
Thermodynamic Properties ◽  
Debye Temperature ◽  
First Principles ◽  
Density Functional ◽  
Coefficient Of Thermal Expansion ◽  
Local Density ◽  
Debye Model ◽  
First Principles Calculations ◽  
Generalized Gradient ◽  
Experimental Values

The structural, elastic and thermodynamic properties of the A15 structure V3Ir, V3Pt and V3Au were studied using first-principles calculations based on the density functional theory (DFT) within generalized gradient approximation (GGA) and local density approximation (LDA) methods. The results have shown that both GGA and LDA methods can process the structural optimization in good agreement with the available experimental parameters in the compounds. Furthermore, the elastic properties and Debye temperatures estimated by LDA method are typically larger than the GGA methods. However, the GGA methods can make better prediction with the experimental values of Debye temperature in V3Ir, V3Pt and V3Au, signifying the precision of the calculating work. Based on the E–V data derived from the GGA method, the variations of the Debye temperature, coefficient of thermal expansion and heat capacity under pressure ranging from 0 GPa to 50 GPa and at temperature ranging from 0 K to 1500 K were obtained and analyzed for all compounds using the quasi-harmonic Debye model.

scholarly journals Pressure Effect on Elastic Constants and Related Properties of Ti3Al Intermetallic Compound: A First-Principles Study

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2015 ◽  
Author(s):  
Xianshi Zeng ◽  
Rufang Peng ◽  
Yanlin Yu ◽  
Zuofu Hu ◽  
Yufeng Wen ◽  
...  
Keyword(s):  
Intermetallic Compound ◽  
Debye Temperature ◽  
Elastic Constants ◽  
First Principles ◽  
Density Functional ◽  
Mechanical Stability ◽  
Theoretical Data ◽  
Young’S Moduli ◽  
Anisotropic Factor ◽  
Isotropic Pressure

Using first-principles calculations based on density functional theory, the elastic constants and some of the related physical quantities, such as the bulk, shear, and Young’s moduli, Poisson’s ratio, anisotropic factor, acoustic velocity, minimum thermal conductivity, and Debye temperature, are reported in this paper for the hexagonal intermetallic compound Ti 3 Al. The obtained results are well consistent with the available experimental and theoretical data. The effect of pressure on all studied parameters was investigated. By the mechanical stability criteria under isotropic pressure, it is predicted that the compound is mechanically unstable at pressures above 71.4 GPa. Its ductility, anisotropy, and Debye temperature are enhanced with pressure.

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