The thermodynamic properties of cubic fluorite-type MgF2: first-principles prediction

Sun, Xiaowei; Liu, Zi‐Jiang; Song, Tao; Quan, Weilong; Chen, Q F

doi:10.1088/0031-8949/85/06/065707

Cited by 2 publications

(1 citation statement)

References 24 publications

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“…The Debye temperature is a primordial parameter in solid-state physics. Because of its relevance to the thermal response of crystals [32] it is used as a distinctive temperature between high and low temperature limits for solids [33]. Using the average sound velocity (v m ), the Debye temperature (θ D ) may be expressed as follows [32]:…”

Section: Thermal Propertiesmentioning

confidence: 99%

Computational insight on the structural, mechanical and thermal properties of Cu2CdSnSe4 and Cu2HgSnSe4 adamantine materials

Bensalem¹,

Chegaar²,

Bouhemadou³

2016

Condens. Matter Phys.

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Through first-principles calculation based on the density functional theory (DFT) within the pseudo potentialplane wave (PP-PW) approach, we studied the structural, mechanical and thermal properties of Cu 2 CdSnSe 4 and Cu 2 HgSnSe 4 adamantine materials. The calculated lattice parameters are in good agreement with experimental and theoretical reported data. The elastic constants are calculated for both compounds using the static finite strain scheme. The hydrostatic pressure action on the elastic constants predicts that both materials are mechanically stable up to 10 GPa. The polycrystalline mechanical parameters, i.e., the anisotropy factor (A), bulk modulus (B ), shear modulus (G), Young's modulus (E ), Lame's coefficient (λ) and Poisson's ratio (ν) have been estimated from the calculated single crystal elastic constants. The analysis of B /G ratio shows that the two studied compounds behave as ductile. Based on the calculated mechanical parameters, the Debye temperature and the thermal conductivity have been probed. In the framework of the quasi-harmonic approximation, the temperature dependence of the lattice heat capacity of both crystals has been investigated.

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Section: Thermal Propertiesmentioning

confidence: 99%

Computational insight on the structural, mechanical and thermal properties of Cu2CdSnSe4 and Cu2HgSnSe4 adamantine materials

Bensalem¹,

Chegaar²,

Bouhemadou³

2016

Condens. Matter Phys.

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Numerical prediction of structural stability and thermodynamic properties for MgF2 with fluorite- type structure under high pressure

Sun¹,

Song²,

Liu³

et al. 2020

Acta Phys. Sin.

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MgF2 is an important member of alkaline-earth fluorides and has a wide range of applications in industry. Meanwhile, MgF2 occurs naturally as a mineral sellaite. Compared with the study of its electronic structure and optical properties, the researches of the behavior under high pressure of MgF2, especially the thermodynamic properties are still limited. The high-pressure melting, volume thermal expansion coefficient, and thermoelastic parameter of the Earth’s lower mantle mineral, like MgF2, are of interest and importance for understanding the physical nature of the functional material and for recognizing the structural compositions, dynamics, evolution and origin of the earth. Using the first-principles calculations based on density functional theory, the thermodynamic, mechanical, and dynamic stability of the fluorite-type structure for MgF2 are systematically studied. The calculations indicate that the fluorite-type structure is a high-pressure phase and it is stable at least up to 135 GPa. According to the principle of equal enthalpies, the phase transition pressure of MgF2 crystal from stable rutile structure to high pressure fluorite structure is determined to be 19.26 GPa and 18.15 GPa based on the the generalized gradient approximation and local density approximation calculations, respectively. The high-temperature structural stability of MgF2 with the fluorite-type structure is investigated and confirmed by using the classical molecular dynamics (MD) simulations by taking into account the molar volume and total energy change behavior in a temperature range from 300 to 6000 K. On the basis of previous research, the volume thermal expansion coefficient, isothermal bulk modulus, and thermoelastic parameter of MgF2 with the CaF2-type fluorite structure are predicted systematically in a temperature range from 300 to 1500 K and in a pressure range from 0 to 135 GPa with the help of the generalized gradient approximation of the revised Perdew-Burke-Ernzerhof form combined with quasiharmonic Debye model calculations and the molecular dynamics method combined with reliable interatomic potentials. An important discovery is that the thermoelastic parameter of this material under low temperature and low pressure is not a constant as assumed usually in previous studies of the equation of states, but it approaches to a constant under both high temperature and high pressure.

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The thermodynamic properties of cubic fluorite-type MgF₂: first-principles prediction

Cited by 2 publications

References 24 publications

Computational insight on the structural, mechanical and thermal properties of Cu2CdSnSe4 and Cu2HgSnSe4 adamantine materials

Computational insight on the structural, mechanical and thermal properties of Cu2CdSnSe4 and Cu2HgSnSe4 adamantine materials

Numerical prediction of structural stability and thermodynamic properties for MgF<sub>2</sub> with fluorite- type structure under high pressure

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