Thermoelectric Properties of Quasicrystalline Approximant in Al–Cu–Ir System

• Published in: MATERIALS TRANSACTIONS Vol. 60; no. 12; pp. 2490 - 2498
• Main Authors: Kitahara, Koichi, Takagiwa, Yoshiki, Kimura, Kaoru
• Format: Journal Article
• Language: English
• Published: Sendai The Japan Institute of Metals and Materials 01-12-2019; Japan Science and Technology Agency
• Subjects: Aluminum; Approximation; Copper; Curve fitting; Electric arc melting; electronic structure; Figure of merit; Heat treatment; Mathematical analysis; Plasma arc heating; Plasma sintering; Properties (attributes); quasicrystalline approximant; Relaxation time; Seebeck effect; Spark plasma sintering; Temperature dependence; Thermal conductivity; thermoelectric properties; Thermoelectricity; Time dependence
• ISSN: 1345-9678; 1347-5320
• DOI: 10.2320/matertrans.M2019073

The thermoelectric properties of a cubic quasicrystalline approximant in the Al–Cu–Ir system were investigated experimentally and theoretically. A homogeneous sample with no secondary phase was synthesised by arc melting and spark plasma sintering followed by a 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 electrons. The experimental Seebeck coefficient was consistently reproduced, and a physically acceptable lattice thermal conductivity was estimated only under the constant-diffusion-coefficient approximation. The 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 theoretical calculation under the rigid-band approximation. This Paper was Originally Published in Japanese in J. Japan Inst. Met. Mater. 82 (2018) 188–196.