Abstract

The electrical resistivity and Seebeck coefficient of (R_0.9Ca_0.1)CoO₃ (R = Gd, Sm, Nd, Pr) rapidly decrease with increasing ionic radius of the rare-earth element, and the Seebeck coefficients (p-type) are fairly high at low temperatures and attain low and constant values at high temperatures; (Pr_0.9Ca_0.1)CoO₃ shows the highest figure-of-merit, 1.3 × 10⁻⁴ K⁻¹ at 85 °C, although this rapidly decreases with temperature above 300 °C due to the decreasing Seebeck coefficient and increasing electronic thermal conductivity.