Koichi Kitahara 1, 2, Yoshiki Takagiwa 1, 3 and Kaoru Kimura 1, 2
1 Department of Advanced Materials Science, Graduate School of Frontier Sciences, The University of Tokyo
Thermoelectric properties of a cubic quasicrystalline approximant in Al-Cu-Ir system were investigated experimentally and theoretically. A homogeneous sample with no secondary phase was synthesized using an arc-melting and a spark-plasma-sintering processes followed by heat treatment at 1173 K, and its thermoelectric properties were measured at temperatures between 373 K and 1023 K. Theoretical calculations of the thermoelectric properties were performed under three different approximations, i.e., constant-relaxation-time, constant-mean-free-path, and constant-diffusion-coefficient approximations, for the energy dependence of the relaxation time of the electrons. The experimental Seebeck coefficient was well reproduced, and physically acceptable lattice thermal conductivity was estimated only under constant-diffusion-coefficient approximation for the present material. Thermoelectric figure of merit zT of the present sample was lower than 0.1, and the maximum value of zT ≈ 0.3 achievable by electron doping was predicted by the theoretical calculation under the rigid-band approximation.
quasicrystalline approximant, thermoelectric properties, electronic structure
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