Various compositions of AlGaPdRe icosahedral quasicrystals (QCs) were synthesized using arc-melting and annealing methods, and their thermoelectric properties were investigated. With the same trend in the Seebeck coefficient as AlPdMn and AlPdRe QCs, the AlGaPdRe QC has a similar pseudogap electronic structure near the Fermi level. More particularly, we found that a sample with a nominal composition of Al66Ga4Pd21Re9exhibited a higher Seebeck coefficient of 90μVK-1at 373 K, and is thus a highly efficient thermoelectric material. This dense sample, having neither cracks nor pores, shows a 1.5 times higher dimensionless figure of merit ZT of 0.18 compared with sintered Al71Pd20Re9. ZT enhancement through Ga substitution for Al is enabled through an increase in both electrical conductivity and Seebeck coefficient, and a decrease in phonon thermal conductivity. This behavior is discussed in terms of the precipitation of metallic secondary phases and the "weakly bonded rigid heavy clusters (WBRHCs)" scheme applicable to cluster-based solids including quasicrystals.
- Spark plasma sintering
- Thermoelectric materials