Thermoelectric Properties of Correlated Electron Systems Ln3Pt4Ge6 and LnPt4Ge12 (Ln = Ce, Pr) and Non-centrosymmetric X2T12P7 (X = Yb, Hf and T = Fe, Co)

We report measurements of the thermoelectric power S and electrical resistivity. for correlated electron systems Ln(3)Pt(4)Ge(6) and LnPt(4)Ge(12) (Ln = Ce, Pr) and X2T12P7 (X = Yb, Hf and T = Fe, Co). The thermoelectric power factor S-2/rho is utilized as a means to assess the potential viability of these materials for thermoelectric applications. S is observed to be sensitive to Ln in Ln(3)Pt(4)Ge(6) and LnPt(4)Ge(12) with Ce-based compounds providing a much larger S and S2/rho than Pr-based materials. The character of S for the Ce-based compounds is consistent with an intermediate Ce valence. In the case of X2T12P7 compounds reported herein, it appears that it is possible to tune the magnitude of S more effectively by varying T rather than X; the magnitude of S is significantly larger with T = Fe than when T = Co.