High-pressure phase transition and thermodynamic properties of MgSe: Ab initio study

2009 ◽  
Vol 87 (2) ◽  
pp. 169-174 ◽  
Author(s):  
Hongzhi Fu ◽  
WenFang Liu ◽  
Tao Gao
Keyword(s):  
Heat Capacity ◽  
Thermodynamic Properties ◽  
Ab Initio ◽  
Cesium Chloride ◽  
Debye Model ◽  
Relative Volume ◽  
Rock Salt Structure ◽  
High Pressure Phase Transition ◽  
Salt Structure ◽  
Pressure Phase

The transition phase of MgSe from a rock salt structure (B1) to a cesium chloride structure(B2) is investigated by ab initio calculations. The thermodynamic properties of the B1 and B2 structures are obtained through the quasi-harmonic Debye model. Moreover, the dependences of the relative volume V/V0 on the pressure P, the Debye temperature Θ, and heat capacity CV on the pressure P, as well as the heat capacity CV on the temperature T are estimated.

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.

First-Principles Calculations of Elastic and Thermodynamic Properties of Cubic CdTe

2011 ◽  
Vol 268-270 ◽  
pp. 886-891
Author(s):  
Ben Hai Yu ◽  
Dong Chen
Keyword(s):  
Experimental Data ◽  
Heat Capacity ◽  
Thermodynamic Properties ◽  
Bulk Modulus ◽  
First Principles ◽  
Debye Model ◽  
First Principles Calculations ◽  
Lattice Constants ◽  
Temperature And Pressure ◽  
The Relationship

the equilibrium lattice constants, elastic and thermodynamic properties of cubic CdTe are systemically investigated at high temperature using the plane-wave pseudopotential method as well as the quasi-harmonic Debye model. The bulk modulus of CdTe are calculated as a function of temperature up to 1000K, the relationship between bulk modulusBand pressure is also obtained. The results gained from this model will provide overall predictions accurately for the temperature and pressure dependence of various quantities such as the bulk modulus, the heat capacity and the thermal expansion coefficient. More over, the dependences between Debye temperature and temperature are also successfully obtained. Our results are compared with the experimental data and discussed in light of previous works.

scholarly journals Iron and sulfur isotope factors for pyrite from experimental gamma-resonant studies and heat capacity

2019 ◽  
Vol 64 (4) ◽  
pp. 372-386
Author(s):  
V. B. Polyakov ◽  
E. G. Osadchii ◽  
M. V. Voronin ◽  
V. O. Osadchii ◽  
L. V. Sipavina ◽  
...  
Keyword(s):  
Heat Capacity ◽  
Kinetic Energy ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Temperature Dependence ◽  
Isotope Exchange ◽  
Resonant Scattering ◽  
Debye Model ◽  
Crystalline Lattice ◽  
Thermal Vibrations

Pyrite Moessbauer spectra (FeS2) is measured in the temperature range from 90 to 295 K. The temperature dependence of the isomer shift is described by the Debye model with Moessbauer temperature θM=551.4 K. Using these results, we calculated the kinetic energy of thermal vibrations of the iron sublattice of pyrite and the iron β-factor for pyrite: 103lnβ57Fe/54Fe=(1.2665±0.0391)x–(0.4584±0.0283) × 10-2x2+(0.2581±0.0239) × 10-4x3; x=106/T 2 (K-2) The Moessbauer-derived iron β-factor for pyrite agrees well with results of ab initio calculations, 57Fe nuclear inelastic γ-resonant scattering synchrotron experiments and direct isotope exchange experiments between pyrite and Fe2+ dissolved in water. Heat capacity of pyrite is measured at temperatures from 79 to 300 K. Its temperature dependence are described using the Thirring expansion. Based on this expansion, the kinetic energy of thermal vibrations of total crystalline lattice of pyrite is calculated. The kinetic energy of the thermal vibrations of the sulfur sublattice in pyrite is found by subtracting the iron sublattice kinetic energy from the total kinetic energy of pyrite crystalline lattice. Temperature dependence of 34S/32S β-factor for pyrite calculated from the kinetic energy of the sulfur sublattice is following: 103lnβ34Fe/32Fe=(1.7532±0.0623) x–(1.0470±0.0752) × 10-2 x2+(1.0424±0.1126) × 10-4 x3; x=106/T 2 (K-2) This 34S/32S β-factor values exhibit a good agreement with of ab initio calculations and isotope-exchange experimental results in the pyrite-sphalerite-galenite system.

THERMODYNAMIC PROPERTIES OF MC (M = V, Nb, Ta): FIRST-PRINCIPLES CALCULATIONS

2013 ◽  
Vol 27 (19) ◽  
pp. 1341035 ◽  
Author(s):  
YONG CAO ◽  
JINGCHUAN ZHU ◽  
YONG LIU ◽  
ZHISHEN LONG
Keyword(s):  
Experimental Data ◽  
Heat Capacity ◽  
Thermodynamic Properties ◽  
Bulk Modulus ◽  
First Principles ◽  
Linear Expansion ◽  
Debye Model ◽  
Linear Expansion Coefficient ◽  
First Principles Calculations ◽  
Temperature Dependences

Through the quasi-harmonic Debye model, the pressure and temperature dependences of linear expansion coefficient, bulk modulus, Debye temperature and heat capacity have been investigated. The calculated thermodynamic properties were compared with experimental data and satisfactory agreement is reached.

Estimation of the heat capacity of CdTe semiconductor

2016 ◽  
Vol 30 (04) ◽  
pp. 1650026 ◽  
Author(s):  
Hüseyin Koç ◽  
Erhan Eser
Keyword(s):  
Heat Capacity ◽  
Thermodynamic Properties ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Binomial Coefficient ◽  
Debye Model ◽  
The Other ◽  
Temperature Range ◽  
Theoretical Results ◽  
Good Agreement

The aim of this paper is to provide a simple and reliable analytical expression for the thermodynamic properties calculated in terms of the Debye model using the binomial coefficient, and examine specific heat capacity of CdTe in the 300–1400 K temperature range. The obtained results have been compared with the corresponding experimental and theoretical results. The calculated results are in good agreement with the other results over the entire temperature range.

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.

Thermodynamic Properties of Nb4AlC3

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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