POSSIBLE ROLE OF Pb IN Bi2−xPbxSr2Ca2Cu3Oy SYSTEM

The preliminary study on the electron spin resonance (ESR) for the Bi2−xPbxSr2Ca2Cu3Oy 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 Cu3+/Cu2+ ratio in the bismuth based systems. A possible role of Pb in the Bi2−xPbxSr2Ca2Cu3Oy system is discussed.