SUPERCONDUCTIVITY AND CARRIER CONCENTRATION OF SINGLE PHASE (Bi,Pb) 2 Sr 2 Ca 2 Cu 3 O y SAMPLES

Single phase (Bi, Pb)2Sr2Ca2Cu3Oy samples have been prepared with different heat treatments. X-ray diffraction, the dependence of resistance on temperature, ac. susceptibility and Hall coefficient have been investigated. We find that all samples are of 2223 single phase, the midpoint superconducting transition temperatures (Tc) are above 100K, and Tc increases mo-notonically with the carrier concentration (nH). The experimental results show that the conditions of heat treatment affect the phase structure, Tc and nH for the Bisystem. We propose that Tc and nH. of the Bi-system are closely related to oxygen content, local composition and structure perfection.