2009 Volume 50 Issue 7 Pages 1725-1729
To improve thermoelectric performance of p-type, Ca-Mg-Si alloys were synthesized by mechanical alloying (MA) and/or solid-liquid reaction (SLR). The Ca16.7Mg50.0Si33.3 − MA + SLR (synthesized by SLR with milling powder) and the Ca16.7Mg45.5Si33.3Ag0.5 − MA +SLR were composed of the phases of Mg2Si, CaMgSi and Ca7Mg7.25Si14. Their seebeck coefficient α showed positive, and their power factor P values were 0.02×10−3 W·m−1·K−2 (670 K) and 0.4×10−3 W·m−1·K−2 (730 K) respectively. The Ca25.0Mg25.0Si50.0 − SLR (synthesized by SLR) was composed of the single Ca7Mg7.25Si14 phase, and its α was metallic trend (α\\simeq0) with low electrical resistivity ρ. It is well-known that Mg2Si is n-type semiconductor. These results indicate that the CaMgSi is p-type. Its α was estimated at 750∼900 μV·K−1 (p-type) at 600 K and its ρ was lower than that of Mg2Si above 600 K. The P of CaMgSi single phase is expected more than 1.4×10−3 W·m−1·K−2 (600 K). Thus, CaMgSi is attractive material with high thermoelectric performance of p-type.
