Influences of Sintering Time on the TC of Bi2-xCuxPb0.3Sr2Ca2Cu3O10+δ High Temperature Superconductors

Solid state thermodynamical reaction method involving mixing, calcinations and sintering were used to prepare a high temperature superconductor with a nominal composition Bi2-xCuxPb0.3Sr2Ca2Cu3O10+δ for Cu (0 d x d 0.5). The effect of sintering time and substituting Cu on Bi sites have been investigated by X-ray diffraction, resistance measurements and oxygen content to obtain the optimum conditions for the formation and stabilization of the high TC phase (2223-phase). The results showed that the optimum sintering time for the composition Bi2-xCuxPb0.3Sr2Ca2Cu3O10+δ is 140 hr at sintering temperature 860 oC. Substitution for Cu equals to 0.2 and 0.3 led to increase the transition temperature to TC =127 K and 130 K respectively but for 0.4, TC decreased to 125 K. The X-ray diffraction (XRD) analysis showed that all samples have almost two phases: high-TC phase (2223-phase) and low-TC phase (2212-phase) in addition to the existing of very low phase in the sample x=0.4. It was found that the all samples having an orthorhombic.