Influence of sintering time and quenching on the formation of high T _c phase

Influence of sintering time and quenching in Bi_{2 -x} Pb _x Ca₂Sr₂Cu₃O _y (x=0.0, 0.1, 0.2, 0.25, 0.3 and 0.4) samples have been studied by resistance and XRD measurements. In samples sintered at 850°C for 4 days, T _c(0) increases with Pb concentration. T _c(0) increased from 81 K for x=0.0 to 109 K in x=0.30 sample and then decreased. Increasing the sintering time to 10 days decreased the T _c Quenching further decreased the T _c(0). From X-ray diffraction patterns, the intensity peaks of low and high T _c phases have been measured. The addition of Pb promotes high T _c-phase. Sintering time, slow cooling and rapid quenching studies show that there is an optimum sintering time and cooling rate to produce a high T _c-phase.