Thermoelectric properties of alkaline-earth silicides

The polycrystalline samples of BaSi₂, SrSi₂, and LaSi were prepared by spark plasma sintering (SPS). The electrical resistivity (rho) and Seebeck coefficient (S) were measured above room temperature. The S of BaSi₂ was negative and the absolute values were rather high (-669 muVK^-1 at 337 K). The S of SrSi₂ was positive and the absolute values were lower (118 muVK^-1 at 332 K) than those of BaSi₂. For LaSi, both the rho and S were very low (2.38 muOmegam and -1.5 muVK^-1 at 333 K, respectively) like metals. The power factor (S²/rho) was quite low (below 10^-5 Wm^-1K^-2 over the whole temperature range) for BaSi₂ and LaSi, while relatively high (1.19 x 10^-3 Wm^-1K^-2 at 331 K) for SrSi₂.