Thermoelectric property of Na-Doped Mg2Si

Abstract

First-principles calculation revealed that Na atoms were expected to be primarily located Mg sites in Mg2Si. Densities of electronic states of the Na-doped MgaSi showed p-type. To obtain a good p-type thermoelectric material, Na-doped Mg2Si (Mg66.7-xSi33.3Na x) were fabricated by solid-liquid reaction using spark plasma sintering. The X-ray diffraction experiments showed that the prepared samples were composed of a single Mg2Si phase. Electrical resistivity, p, and Seebeck coefficient, α, were measured in the temperature range from room temperature to around 600 K for samples with various Na contents. The a of samples in the Na composition range of x≥0.5 were positive values (p-type). The results of first-principles calculation and experiment showed that Na was employed as acceptor in Mg2Si system. The maximum power factor of 0.44 × 10-3 W·m-1·K-2 was obtained at 313 K for the Mg65.7Si33.3Na1.0 sample. © 2008 The Japan Institute of Metals.