The mechanical and thermodynamic properties of ZrAl2 under pressure from first-principles investigation

2016 ◽  
Vol 27 (01) ◽  
pp. 1650001
Author(s):  
Ning Wei ◽  
Xuefei Wang ◽  
Xuzhong Zuo
Keyword(s):  
Heat Capacity ◽  
High Pressure ◽  
Thermodynamic Properties ◽  
Debye Temperature ◽  
First Principles ◽  
Density Functional ◽  
Applied Pressure ◽  
Debye Model ◽  
Effect Of Temperature ◽  
Expansion Formula

The mechanical and thermodynamic properties of ZrAl2 alloy under high pressure are investigated by first-principles based on the density functional theory. Due to all the elastic constants of ZrAl2 alloy satisfy generalized stabilities criteria, ZrAl2 is mechanically stable under pressure up to 100[Formula: see text]GPa. By analyzing the value of B/G and Poisson’s ratio [Formula: see text] which are correlated with the ductility and brittleness of material, we found that ZrAl2 belongs to brittle material at pressure of 0–70[Formula: see text]GPa and will change from brittleness to ductility at 70[Formula: see text]GPa. Combining with high bulk modulus B and shear modulus G, the mechanical of properties will be improved under high pressure. Moreover, the thermodynamic properties, such as the Debye temperature [Formula: see text], heat capacity [Formula: see text] and thermal expansion [Formula: see text], are discussed using the quasi-harmonic Debye model. We noted that the Debye temperature [Formula: see text] is mainly dependent on the pressure and the effect of temperature on the heat capacity [Formula: see text] is more important than the applied pressure.

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.

First-Principles Investigations on Structural, Elastic, and Thermodynamic Properties of Ce-La Alloys Under High Pressure

2014 ◽  
Vol 69 (1-2) ◽  
pp. 52-60
Author(s):  
Li-Qin Zhang ◽  
Yan Cheng ◽  
Zhen-Wei Niu ◽  
Guang-Fu Ji
Keyword(s):  
Heat Capacity ◽  
High Pressure ◽  
Thermal Expansion ◽  
Thermodynamic Properties ◽  
Electronic Properties ◽  
Ground State ◽  
First Principles ◽  
Debye Model ◽  
First Principles Calculations ◽  
Charge Densities

The structural stability, thermodynamic, elastic, and electronic properties of cerium (Ce)- lanthanum (La) alloys were investigated for different Ce/La ratios under pressure by first-principles calculations using on-the-fly (OTF) pseudopotential and general gradient approximation (GGA). The ground-state properties of lanthanum and cerium obtained by minimizing the total energy agree favourably with other work.We derived the elastic constants, bulk modulus, and shear modulus of the La-Ce alloys for different Ce/La ratios. Using the quasi-harmonic Debye model, the thermodynamic properties of the La-Ce alloys including the thermal expansion coefficient α and heat capacity Cv are successfully obtained in the temperature range from 0 K to 1000 K. Furthermore, the electronic properties such as density of states and charge densities were also studied.

First-principles study of the phonon, mechanical and thermodynamic properties of B2-phase AlY under high pressures

2017 ◽  
Vol 31 (32) ◽  
pp. 1750254
Author(s):  
Leini Wang ◽  
Zhang Jian ◽  
Wei Ning
Keyword(s):  
High Pressure ◽  
Thermodynamic Properties ◽  
Elastic Constants ◽  
First Principles ◽  
Density Functional ◽  
High Pressures ◽  
Mechanical Stability ◽  
Debye Model ◽  
Functional Theory ◽  
B2 Phase

We have investigated the phonon, mechanical and thermodynamic properties of B2-phase AlY under high pressure by performing density functional theory (DFT). The result of phonon band structure shows B2-phase AlY exhibits dynamical stability. Then, the elastic properties of AlY under high pressure have been discussed. The elastic constants of AlY increase monotonically with the increase of the pressure and all the elastic constants meet the mechanical stability standard under high pressure. By analyzing the Poisson’s ratio [Formula: see text] and the value of B/G of AlY, we first predicted that AlY undergoes transformation from brittleness to ductility at 30 GPa and high pressure can improve the ductility. To obtain the thermodynamic properties of B2-phase AlY, the quasi-harmonic Debye model has been employed. Debye temperature [Formula: see text], thermal expansion coefficient [Formula: see text], heat capacity C[Formula: see text] and Grüneisen parameter [Formula: see text] of B2-phase AlY are systematically explored at pressure of 0–75 GPa and temperature of 0–700 K.

scholarly journals First-Principles Study on the Photoelectric Properties of CsGeI3 under Hydrostatic Pressure

2020 ◽  
Vol 10 (15) ◽  
pp. 5055
Author(s):  
Li-Ke Gao ◽  
Yan-Lin Tang ◽  
Xin-Feng Diao
Keyword(s):  
Heat Capacity ◽  
Free Energy ◽  
Hydrostatic Pressure ◽  
Debye Temperature ◽  
Gibbs Free Energy ◽  
First Principles ◽  
Density Functional ◽  
Applied Pressure ◽  
Perovskite Solar Cells ◽  
Photoelectric Properties

CsGeI3 has been widely studied as an important photoelectric material. Based on the density functional theory (DFT), we use first-principles to study the photoelectric properties of CsGeI3 by applying successive hydrostatic pressure. It has been found that CsGeI3 has an optimal optical band gap value of 1.37 eV when the applied pressure is −0.5 GPa, so this paper focuses on the comparative study of the photoelectric properties when the pressure is −0.5 GPa and 0 GPa. The results showed that CsGeI3 has a higher dielectric value, conductivity, and absorption coefficient and blue shift in absorption spectrum when the pressure is −0.5 GPa. By calculating and comparing the effective masses of electrons and holes and the exciton binding energy, it was found that their values are relatively small, which indicates that CsGeI3 is an efficient light absorbing material. CsGeI3 was found to be stable under both pressure conditions through multiple calculations of the Born Huang stability criterion, tolerance factor T, and phonon spectrum with or without virtual frequency. We also calculated the elastic modulus of both pressure conditions and found that they are both soft, ductile, and anisotropic. Finally, the thermal properties of CsGeI3 under two kinds of pressure were studied. It was found that the Debye temperature and heat capacity of CsGeI3 increased with the increase of thermodynamic temperature, and the Debye temperature increased rapidly after pressure, while the heat capacity slowly increased and finally stabilized. Through the calculation of enthalpy, entropy, and Gibbs free energy of CsGeI3, it was found that the Gibbs free energy decreases faster with the increase of temperature without applied pressure, which indicates that CsGeI3 has a higher stability without pressure. Through the comparative analysis of the photoelectric properties of CsGeI3 under pressure, it was found that CsGeI3 after applied pressure is a good photoelectric material and suitable for perovskite solar cells (PSCs) material.

First-principles investigations on the elastic and thermodynamic properties of cubic ZrO2 under high pressure

2015 ◽  
Vol 26 (05) ◽  
pp. 1550056 ◽  
Author(s):  
Ning Wei ◽  
Xiaoli Zhang ◽  
Chuanguo Zhang ◽  
Songjun Hou ◽  
Z. Zeng
Keyword(s):  
High Pressure ◽  
Thermodynamic Properties ◽  
First Principles ◽  
Density Functional ◽  
Debye Model ◽  
Pressure Effects ◽  
Ductile Material ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Resistance To Deformation

We have investigated the elastic and thermodynamic properties of ZrO 2 under pressure up to 120 Gpa by the plane wave pseudopotential density functional theory with the generalized gradient approximation (GGA) method. The elastic constants of ZrO 2 are calculated and meet the generalized stability criteria, suggesting that ZrO 2 is mechanically stable within this pressure range. The pressure effects on the elastic properties reveal that the elastic modulus B, shear modulus G and Young's modulus Y increase linearly with the pressure increasing, implying that the resistance to deformation is enhanced. In addition, by analyzing the Poisson's ratio ν and the value of B/G, we notice that ZrO 2 is regarded as being a ductile material under high pressure and the ductility can be improved by the pressure increasing. Then, we employ the quasi-harmonic Debye model considering the phononic effects to obtain the thermodynamic properties of ZrO 2. Debye temperature ΘD, thermal expansion coefficient α, heat capacity Cp and Grüneisen parameter γ are systematically explored at pressure of 0–80 Gpa and temperature of 0–1000 K. Our results have provided fundamental facts and evidences for further experimental and theoretical researches.

DFT study of electronic and thermodynamic properties of gold-rich intermetallic compounds, Ce2Au2Cd and CeAu4Cd2

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Jyoti Sagar ◽  
Reetu Singh ◽  
Vijay Kumar ◽  
Sanjay Kumar ◽  
Manish P. Singh ◽  
...  
Keyword(s):  
Thermodynamic Properties ◽  
Mechanical Strength ◽  
Intermetallic Compounds ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Debye Model ◽  
Effect Of Temperature ◽  
Mechanical Resistance ◽  
Electronic Band ◽  
High Mechanical Strength

Abstract Gold-rich rare earth intermetallic compounds (viz. Ce2Au2Cd and CeAu4Cd2) show unusual magnetic and physical properties, and they have extensive applications in electronic and mechanical industries due to their good electronic and thermal behavior with high mechanical strength. In the present research article, to take full advantage of technological importance of these materials, we have investigated the structural, electronic and thermodynamic properties of Ce2Au2Cd and CeAu4Cd2 ternary intermetallic compounds using density functional theory (DFT). The electronic band structure and density of state calculations show that Ce-f orbital electrons provide metallic character to both the compounds with strong hybridization of Au-p and Cd-p orbitals at the Fermi level. The effect of temperature has been studied on the various thermodynamic parameters using the quasi-harmonic Debye model. Thermodynamic properties show that CeAu4Cd2 compound has larger mechanical resistance (or high mechanical strength or hardness) and smaller randomness compared to Ce2Au2Cd with respect to temperature.

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.

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.

Study of Thermodynamic Properties of Superhard w-BC2N

2013 ◽  
Vol 750-752 ◽  
pp. 1141-1145
Author(s):  
Ai Ling Ding ◽  
Feng Li ◽  
Chun Mei Li ◽  
Jing Ao ◽  
Zhi Qian Chen
Keyword(s):  
Density Functional Theory ◽  
Heat Capacity ◽  
Thermodynamic Properties ◽  
Density Functional ◽  
Local Density ◽  
Density Functional Theory Method ◽  
Debye Model ◽  
Theory Method ◽  
Density Approximation ◽  
Functional Theory

We investigate the thermodynamic properties of superhard w-BC2N by using ab initio plane-wave pseudopotential density functional theory method within local density approximation (LDA). Through the quasi-harmonic Debye model, we investigate the thermodynamic properties of w-BC2N. The variation of the thermal expansion, the heat capacity and the Gruneisen parameter γ with pressure P and temperature T, and many other thermodynamic parameters of w-BC2N are obtained systematically.

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