POSSIBLE ROLE OF Pb IN Bi_2−xPb_xSr₂Ca₂Cu₃O_y SYSTEM

Abstract

The preliminary study on the electron spin resonance (ESR) for the Bi 2−x Pb x Sr 2 Ca 2 Cu 3 O y system has been made at room temperature. It is found that no significant ESR signal appears for Pb-substituted BiPbSrCaCuO system at RT, but a strong ESR signal was found for BiSrCaCuO system with 90 K superconducting transition under the same experimental conditions. These might be attributed to the Cu 3+ / Cu 2+ ratio in the bismuth based systems. A possible role of Pb in the Bi 2−x Pb x Sr 2 Ca 2 Cu 3 O y system is discussed.