Propagation velocity of longitudinal and transverse acoustic waves and anharmonicity of lattice oscillations

Сандитов, Д. С.; Машанов, А. А.; Darmaev, M. V.

doi:10.1134/s1063784209090254

Cited by 36 publications

(17 citation statements)

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“…Θ a in eq can be calculated by the obtained υ a through the following equation , where ℏ is the Planck constant and Ω is the cell volume. Grüneisen parameter γ can also be obtained as follows …”

Section: Methodsmentioning

confidence: 99%

Remarkably High Thermoelectric Efficiencies of the Half-Heusler Compounds BXGa (X = Be, Mg, and Ca)

Sun

Yang

2020

ACS Appl. Mater. Interfaces

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The thermoelectric materials with high values of the dimensionless figure of merit (ZT) are among the most important new energy resources. Too much attention has been paid to the search of high-ZT thermoelectric materials, and the one with ZT = 5 has been reported recently. Here, a remarkably high ZT = 7.38 is predicted for the n-type half-Heusler compound of BCaGa at 700 K. To understand the high-ZT behavior, we studied electronic properties of BXGa (X = Be, Mg, and Ca) with first-principles calculations based on the density functional theory. The stabilities of the structures of BXGa (X = Be, Mg, and Ca) are confirmed by phonon dispersion. The transport properties are determined by the semiclassical Boltzmann transport theory. We evaluate the relaxation time by using the deformation potential theory and the lattice thermal conductivity based on the elastic coefficients. The results demonstrate that such a high efficiency of BCaGa arises from the intrinsic coordination of the ultralow lattice and electronic thermal conductivity and the larger power factor at certain carrier concentration and temperature. The high n-type power factor originates from the large relaxation time, which results in a light, twofold degenerate conduction-band pocket at the Γ point. In contrast, the power factors of BBeGa and BMgGa are smaller because of their flat-and-dispersive valence band. It is expected that the remarkable results for BXGa could encourage more experimental and theoretical investigations to develop efficient thermoelectric materials with BXGa.

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Section: Methodsmentioning

confidence: 99%

Remarkably High Thermoelectric Efficiencies of the Half-Heusler Compounds BXGa (X = Be, Mg, and Ca)

Sun

Yang

2020

ACS Appl. Mater. Interfaces

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“…The M̅ , δ, n, and T are the average atomic mass, cubic root of volume per atom, number of atoms in a unit cell, and temperature, respectively. The Gruneisen parameter γ can be calculated by 57,58…”

Section: Computational Detailsmentioning

confidence: 99%

Thermal Transport and Mechanical Properties of Layered Oxychalcogenides LaCuOX (X = S, Se, and Te)

Wang

Chen

Sun

et al. 2022

ACS Appl. Energy Mater.

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Layered LaCuOX (X = S, Se, and Te) have great potential for highperformance photoelectric (PE) applications, while little is known about their mechanical and thermal properties. The lack of this information will hinder understanding their transport mechanisms and applications as high TE/PE energy conversion efficiency devices. This study investigates the electronic, mechanical, and thermal properties of LaCuOX compounds. The investigated tetragonal crystals are all found to be mechanically stable. Besides, the mechanical stability and stiffness of layered LaCuOX weaken from LaCuOS to LaCuOTe, while their shear strain resistances are comparable. All the materials show good ductility and have ionic− covalent bonding. Since the Debye temperature and sound velocity decrease from LaCuOS to LaCuOTe, the thermal conductivity increases following the same order. Due to large Gruneisen parameters caused by strong phonon anharmonicity, ultralow thermal conductivities of LaCuOS, LaCuOSe, and LaCuOTe are found to be 2.58, 2.20, and 1.90 W/m K at 300 K, respectively. This work deepens the understanding of the physical properties of LaCuOX crystals, which may benefit in promoting their potential PE and thermoelectric applications.

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“…The transverse sound velocity ν t and longitudinal sound velocity ν l can be calculated via the following formulas. 44 average sound velocity ν m can be calculated from ν t and ν l , , replace ν t , ν l and ν m with expressions for γ and Θ D : 45,46 …”

Section: Resultsmentioning

confidence: 99%

Investigations on the thermoelectric and thermodynamic properties of Y₂CT₂ (T = O, F, OH)

et al. 2022

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Propagation velocity of longitudinal and transverse acoustic waves and anharmonicity of lattice oscillations

Cited by 36 publications

References 1 publication

Remarkably High Thermoelectric Efficiencies of the Half-Heusler Compounds BXGa (X = Be, Mg, and Ca)

Remarkably High Thermoelectric Efficiencies of the Half-Heusler Compounds BXGa (X = Be, Mg, and Ca)

Thermal Transport and Mechanical Properties of Layered Oxychalcogenides LaCuOX (X = S, Se, and Te)

Investigations on the thermoelectric and thermodynamic properties of Y₂CT₂ (T = O, F, OH)

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Propagation velocity of longitudinal and transverse acoustic waves and anharmonicity of lattice oscillations

Cited by 36 publications

References 1 publication

Remarkably High Thermoelectric Efficiencies of the Half-Heusler Compounds BXGa (X = Be, Mg, and Ca)

Remarkably High Thermoelectric Efficiencies of the Half-Heusler Compounds BXGa (X = Be, Mg, and Ca)

Thermal Transport and Mechanical Properties of Layered Oxychalcogenides LaCuOX (X = S, Se, and Te)

Investigations on the thermoelectric and thermodynamic properties of Y2CT2 (T = O, F, OH)

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Investigations on the thermoelectric and thermodynamic properties of Y₂CT₂ (T = O, F, OH)