Thermal Properties of β-Ga2O3 from First Principles

MRS Advances ◽  
2016 ◽  
Vol 1 (2) ◽  
pp. 109-114 ◽  
Author(s):  
Marco D. Santia ◽  
Nandan Tandon ◽  
J. D. Albrecht
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Thermal Expansion ◽  
Bulk Modulus ◽  
Harmonic Approximation ◽  
Boltzmann Transport ◽  
Grüneisen Parameters ◽  
Optical Modes ◽  
Gruneisen Parameters

ABSTRACTThe thermal conductivity, bulk modulus, thermal expansion and heat capacity for bulk β-Ga2O3 are calculated from lattice dynamics using both a quasi-harmonic approximation and an anharmonic force-constant approach involving a solution of the linearized Boltzmann transport equation. The role of anharmonicity in β-Ga2O3 is determined to be small, which leads to the weak volume dependence of the calculated thermal conductivity. The negligible anharmonic contribution to the overall thermal conductivity is consistent with both thermal expansion measurements and also with comparisons between the quasi-harmonic and anharmonic methods. Phonon-mode-dependent Grüneisen parameters are found to be weakly dependent on temperature. Negative values of the mode Grüneisen parameters are found for certain low energy optical modes, but their net effect on the overall thermal expansion is insignificant. Bulk modulus as well as heat capacity are also given and found to be in agreement with experimental results.

Thermal expansion tensors, Grüneisen parameters and phonon velocities of bulk MT2 (M = W and Mo; T = S and Se) from first principles calculations

RSC Advances ◽  
2015 ◽  
Vol 5 (24) ◽  
pp. 18391-18400 ◽  
Author(s):  
Yingchun Ding ◽  
Bing Xiao
Keyword(s):  
Thermal Expansion ◽  
Thermal Properties ◽  
First Principles ◽  
Harmonic Approximation ◽  
First Principles Calculations ◽  
Grüneisen Parameters ◽  
Phonon Spectra ◽  
Gruneisen Parameters

The thermal properties of 2H-MT2 (M = W/Mo, T = S/Se) structures are calculated using the quasi-harmonic approximation based on phonon spectra.

Primary pyroelectric transition temperatures of binary nitrides (AlN, GaN and InN)

2019 ◽  
Vol 33 (05) ◽  
pp. 1950049
Author(s):  
Muralidhar Swain ◽  
Sushant K. Sahoo ◽  
Bijay K. Sahoo
Keyword(s):  
Thermal Conductivity ◽  
Thermal Expansion ◽  
Thermal Properties ◽  
Transition Temperature ◽  
Negative Thermal Expansion ◽  
Polarization Field ◽  
Piezoelectric Polarization ◽  
Polarization Mechanism ◽  
Prior Literature

The primary pyroelectric transition temperature of wurtzite nitrides (AlN, GaN and InN) has been explored theoretically from their thermal properties. The spontaneous and piezoelectric polarization modifies the thermal conductivity of nitrides. The thermal conductivity [Formula: see text] as a function of temperature including and excluding the polarization mechanism predicts a transition temperature [Formula: see text] between primary and secondary pyroelectric effects. Below [Formula: see text], thermal conductivity including polarization field [Formula: see text] is lesser than thermal conductivity excluding polarization field [Formula: see text]. This is due to negative thermal expansion in binary nitrides below [Formula: see text]; however, above [Formula: see text], [Formula: see text]. [Formula: see text] is significantly contributed by piezoelectric polarization above [Formula: see text] due to thermal expansion which is the reason for the secondary pyroelectric effect. The transition temperature [Formula: see text] for AlN, GaN and InN has been predicted as 100 K, 70 K and 60 K, respectively, which fit well with the prior literature studies. This report proposes that thermal properties’ study can reveal the role of acoustic phonons in pyroelectricity.

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