Thermodynamic Properties of CaSiO3 Perovskite at High Pressure and High Temperature

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.

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THERMODYNAMIC PROPERTIES OF MgSiO3 POST-PEROVSKITE

Modern Physics Letters B ◽

10.1142/s0217984910022391 ◽

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.

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

International Journal of Modern Physics B ◽

10.1142/s021797921750254x ◽

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.

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

Modern Physics Letters B ◽

10.1142/s0217984916504145 ◽

2016 ◽

Vol 30 (35) ◽

pp. 1650414 ◽

Cited By ~ 6

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.

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

Materials ◽

10.3390/ma11112091 ◽

2018 ◽

Vol 11 (11) ◽

pp. 2091 ◽

Cited By ~ 13

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.

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Pressure effect on the structural, phonon, elastic and thermodynamic properties of L12phase RH3TA: First-principles calculations

International Journal of Modern Physics B ◽

10.1142/s0217979218501692 ◽

2018 ◽

Vol 32 (14) ◽

pp. 1850169

Author(s):

Leini Wang ◽

Zhang Jian ◽

Wei Ning

Keyword(s):

Thermodynamic Properties ◽

Density Functional ◽

Harmonic Approximation ◽

Debye Model ◽

Approximation Model ◽

Functional Theory ◽

The Density Functional Theory ◽

Relationship Of ◽

G Ratio ◽

Wide Pressure

The phonon, elastic and thermodynamic properties of L12phase Rh3Ta have been investigated by the density functional theory (DFT) approach combined with the quasi-harmonic approximation model. The results of the phonon band structure show that L12phase Rh3Ta possesses dynamical stability in the pressure range from 0–80 GPa due to the absence of imaginary frequencies. The pressure dependences with the elastic constants C[Formula: see text], shear modulus G, bulk modulus B, Young’s modulus Y, Poisson’s ratio and B/G ratio have been analyzed. The results of the elastic properties studies show that L12phase Rh3Ta compound is mechanically stable and possesses a higher hardness, improved ductility and plasticity under higher pressures. The pressure and temperature relationship of the thermodynamic properties, such as the Debye temperature [Formula: see text], heat capacity C[Formula: see text], thermal expansion coefficient [Formula: see text] and the Grüneisen parameter [Formula: see text] are predicted by the quasi-harmonic Debye model in a wide pressure (0–80 GPa) and temperature (0–750 K) ranges.

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Study of Thermodynamic Properties of Superhard w-BC2N

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.750-752.1141 ◽

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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PHASE TRANSITION, ELASTIC AND THERMODYNAMIC PROPERTIES OF BERYLLIUM VIA FIRST PRINCIPLES

International Journal of Modern Physics B ◽

10.1142/s0217979213501300 ◽

2013 ◽

Vol 27 (24) ◽

pp. 1350130 ◽

Cited By ~ 3

Author(s):

YAN CHENG ◽

HAI-HUA CHEN ◽

FAN-XIANG XUE ◽

GUANG-FU JI ◽

MIN GONG

Keyword(s):

Phase Transition ◽

Thermodynamic Properties ◽

First Principles ◽

Density Functional ◽

High Pressures ◽

Intermediate Phase ◽

Linear Thermal Expansion ◽

Generalized Gradient ◽

Functional Theory ◽

Bcc Phase

The phase transition, elastic and thermodynamic properties of beryllium (Be) have been studied at high pressures by plane-wave ultrasoft pseudopotential density functional theory (DFT) within the generalized gradient approximation (GGA). It is found that the hcp → bcc phase transition of Be occurs at 506 GPa (T = 0 K ) and occurs at 1200 K (P = 0 GPa ). The coefficients of linear thermal expansion of the hexagmal close-packed (hcp), bcc and orthorhombic Be have been calculated. The hcp → orthorhombic → bcc phase transitions do not occur in all range of pressures, that is to say, the orthorhombic Be is not an intermediate phase between the hcp and bcc Be. The obtained bulk modulus (B0) are 113.2 GPa (for hcp Be), 113.1 GPa (for bcc Be) and 70.5 GPa (for orthorhombic Be), respectively.

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Thermodynamic Properties of Nb4AlC3

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.456.442 ◽

2013 ◽

Vol 456 ◽

pp. 442-446

Author(s):

Ai Ling Ding ◽

Wen Bin Yu ◽

Chun Mei Li ◽

Zhi Qian Chen

Keyword(s):

Thermodynamic Properties ◽

Bulk Modulus ◽

Density Functional ◽

Local Density ◽

Density Functional Theory Method ◽

Debye Model ◽

Relative Volume ◽

Zero Temperature ◽

Functional Theory ◽

Entropy Parameter

We use ab initio plane-wave pseudopotential density functional theory method within local density approximation (LDA) to investigate the thermodynamic properties of Nb4AlC3 under high pressure (0-100 GPa) and high temperature (0-3000 K). Through the quasi-harmonic Debye model, we investigate the thermodynamic properties of Nb4AlC3.The variation of the relative volume, bulk modulus, entropy parameter S, the thermal expansion coefficient α , the heat capacity and the Gruneisen parameter γ with pressure P and temperature T, and many other thermodynamic parameters of Nb4AlC3 are obtained systematically. The bulk modulus of Nb4AlC3 is 250 GPa under zero temperature and zero pressure.

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Structural Phase Transition and Electronic Properties of MgCe under High Pressure from First-Principles Calculations

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.577.102 ◽

2014 ◽

Vol 577 ◽

pp. 102-107

Author(s):

Qiu Xiang Liu ◽

De Ping Lu ◽

Rui Jun Zhang ◽

Lei Lu ◽

Shi Fang Xie

Keyword(s):

Phase Transition ◽

Ground State ◽

First Principles ◽

Electronic Structures ◽

Density Functional ◽

High Pressures ◽

Local Density ◽

Structural Phase ◽

First Principles Calculations ◽

Functional Theory

The structural stability of MgCe under high pressures has been investigated by using the first-principles plane-wave pseudopotential density functional theory within the local density approximation (LDA). The obtained results predict that MgCe in the Ba structure is predicted to be the most stable structure corresponding to the ground state, because of lowest total energy. MgCe undergoes a pressure-induced phase transition from the Ba structure to B32 structure at 36 GPa. And no further transition is found up to 120 GPa. In addition, the electronic structures of four structures of MgCe are also calculated and discussed.

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Insight into Physical and Thermodynamic Properties of X3Ir (X = Ti, V, Cr, Nb and Mo) Compounds Influenced by Refractory Elements: A First-Principles Calculation

Crystals ◽

10.3390/cryst9020104 ◽

2019 ◽

Vol 9 (2) ◽

pp. 104 ◽

Cited By ~ 2

Author(s):

Dong Chen ◽

Jiwei Geng ◽

Yi Wu ◽

Mingliang Wang ◽

Cunjuan Xia

Keyword(s):

Thermodynamic Properties ◽

First Principles ◽

Density Functional ◽

Local Density ◽

First Principles Calculation ◽

Generalized Gradient ◽

Functional Theory ◽

Debye Temperatures ◽

Experimental Parameters ◽

Experimental Values

The effects of refractory metals on physical and thermodynamic properties of X3Ir (X = Ti, V, Cr, Nb and Mo) compounds were investigated using local density approximation (LDA) and generalized gradient approximation (GGA) methods within the first-principles calculations based on density functional theory. The optimized lattice parameters were both in good compliance with the experimental parameters. The GGA method could achieve an improved structural optimization compared to the LDA method, and thus was utilized to predict the elastic, thermodynamic and electronic properties of X3Ir (X = Ti, V, Cr, Nb and Mo) compounds. The calculated mechanical properties (i.e., elastic constants, elastic moduli and elastic anisotropic behaviors) were rationalized and discussed in these intermetallics. For instance, the derived bulk moduli exhibited the sequence of Ti3Ir < Nb3Ir < V3Ir < Cr3Ir < Mo3Ir. This behavior was discussed in terms of the volume of unit cell and electron density. Furthermore, Debye temperatures were derived and were found to show good consistency with the experimental values, indicating the precision of our calculations. Finally, the electronic structures were analyzed to explain the ductile essences in the iridium compounds.

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