[21a-W323-1~10] 9.4 Thermoelectric conversion

[21a-W323-4] Dimensionality of electronic structures and thermoelectric transport properties in layered complex nitrides NaMN₂ (M=Ta, Nb)

〇Isao Ohkubo^1,2, Takao Mori¹ (1.NIMS, 2.JST-PRESTO)

Keywords:Layered complex nitride,Electronic structure calculation

Layered compounds have several advantages with respect to high-performance thermoelectric properties. In this study, we focused on the d⁰-electron layered complex nitrides NaMN₂ (M = Ta, Nb) with alpha-NaFeO₂-type crystal structures. Density-functional theory and Boltzmann theory calculations were performed to determine the electronic structures and thermoelectric transport coefficients of the NaMN₂ compounds, which were compared with that of the three-dimensional d⁰-electron perovskite oxide KTaO₃. NaMN₂ materials were semiconductors with energy band gaps of 1.5–2.2 eV, exhibited anisotropic thermoelectric transport properties, and the electronic structures of their conduction bands appeared to be three-dimensional. The thermoelectric transport properties of NaMN₂ are potentially superior to those of KTaO₃.