THE EFFECTS OF SUBSTITUTION OF SN FOR CU IN BI1.75PB0.25SR2CACU2.3-XSNXSNXOY

The influence of Sn doping on superconductivity in the Bi-based 2212 p hase is studied in this paper. For the samples R-T relations and magne tic hysteresis loops were measured. X-ray powder diffraction analysis was also performed. For Bi1.75Pb0.25Sr2CaCu2.3-xSnxOy, the experimenta l results show that by adding the proper amount of Sn the superconduct ivity of the samples can be improved. As x=0.15, the critical temperat ure T-c, the critical current density J(c), and the magnetic pinning f orce density F reach a maximum. At T=77 K, the critical state paramete rs H-c1, H-c2, kappa, lambda, and xi are calculated and compared with the results reported by other researchers. The experimental results al so show that the Sn doping is able to speed up the growth of the 2223 phase. In brief, Sn doping is an effective way of improving the superc onductivity in Bi-based superconductors.