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

Abstract

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.

Fig. 4 Temperature (T) dependence of the Seebeck coefficient (S) of sample B (open circles) and its best-fitting theoretical curves under CRA (dotted line), CFA (dashed line) and CDA (solid line).