Thermoelectric Properties of Al-Mn-Si Based C54 Phase Containing Small Amount of C40 Phase

Abstract

The dimensionless figure of merit, ZT, of Al-Mn-Si based C54 phase was effectively increased using the precipitation of a small amount of Al-Mn-Si based C40 phase, which possesses slightly smaller magnitude of both electrical resistivity and Seebeck coefficient than those of C54 phase. We prepared a series of samples by simply alloying Al₃₇(Mn₂₆Ru₃Re₃Fe₁)Si₃₀) C54 phase and Al_27.5(Mn₂₉W₃Fe₁)Si_39.5 C40 phase as [Al₃₇(Mn₂₆Ru₃Re₃Fe₁)Si₃₀]_1-x[Al_27.5(Mn₂₉W₃Fe₁)Si_39.5]_x at x = 0, 0.01, 0.02, 0.03, 0.05, and 1, and found that the magnitude of Seebeck coefficient remained unchanged at x < 0.03, while the lattice thermal conductivity and electrical resistivity were moderately decreased with increasing x. The maximum ZT has consequently increased up to ZT = 0.42 at x = 0.03 from ZT = 0.38 of the C54-phase at x = 0.