RELATIONSHIP BETWEEN OXYGEN-CONTENT AND SEEBECK COEFFICIENT OF BI-BASED SUPERCONDUCTING OXIDES

The correlations among Seebeck coefficient, oxygen content and superco nducting property were examined for four Bi-based oxides (2223 and 221 2 phases). Each oxide underwent reversible sorption and desorption of small amounts of oxygen (ca.3x10(-5)mol/g) in the temperature range 10 0-600 degrees C. In good agreement with such behavior, the Seebeck coe fficient (Q) of each oxide was found to change reversibly with changin g temperature, suggesting that Q is a reversible function of oxygen co ntent. It was further found that the highest Tc was reached at the oxy gen content at which Q was incidentally brought to be around zero at 1 00 degrees C for each oxide.