The effect of sintering time on the Bi1.7Pb0.3Ca2Sr2Cu3 Oy sample was investigated through XRD, DC resistance, AC magnetic susceptibility, SEM and critical current density (Jc). The XRD patterns revealed that the intensity of the low angle line at 2θ = 4.7° which corresponds to the high Tc phase, increases gradually with sintering time and reaches a maximum for nearly 200-240 hours. It is also found that the percentage of the high Tc phase is around 94% and that of the low Tc is approximately 6%. DC resistance results also showed an increase in Tc with sintering time and reached a maximum of 110 K. The real part of the AC susceptibility showed a step which corresponds to the transition from a normal to a superconducting state which gradually shifts to higher temperatures with an increase in sintering time. The magnitude of the step, which is a measure of the Meissner signal, also increased gradually with sintering time. The χ″ vs. T plots showed that with increase in sintering time, the width at half maxima decreased and the height of the peak increased. For still longer sintering times (200-240 h) the loss peak became sharper. The Jc value increased linearly with increasing sintering time. SEM studies revealed that the grain size increases and an increase in Jc may therefore be due to a reduction in the number of grain boundaries and other defects such as voids.
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