Thermoelectric Power of Impurity-Substituted YBa₂Cu₃O_7-yat Elevated Temperatures

Abstract

Seebeck coefficients (S) of undoped YBa₂Cu₃O_7-y (YBCO) are negative below about 500°C and changes the sign to plus around 500°C, followed by the sharp increase with temperature up to 900°C. Fe, Co, Ni and Zn are substituted for Cu, La and K for Ba, and Ca for Y. The values of S of impurity-substituted YBCO show the strong dependence on the valency of substituted atoms.