Influence of magnetic field on superconducting transition in Bi-Sr-Ca-Cu-O glass-ceramics

The crystallization and superconducting properties of Bi4Sr3Ca3Cu4Ox glass-ceramics have been investigated. The glass was prepared using the conventional melt-quenching method. X-ray diffraction pattern has shown that the annealing at temperature above 800degreesC converted the glass into glass-ceramics with Bi2Sr2CaCu2Ox superconducting phase (2212-phase). The amounts of 2212 phase in the samples after a different time of annealing (0.5 h-216 h) have been determined by magnetic susceptibility measurements. The superconducing transition exhibits the change in the slope that is characteristic for two different superconducting phases. It is observed that T-c (zero) increases from 20 K to 80 K with increasing time of annealing. The influence of magnetic field on the superconducting transition has been investigated. Our studies revealed a remarkable broadening of the resistive transition with increasing field. The temperature width (T-c-T) of the transition for both phases increases with magnetic field according to Tinkham model. In this model the resistivity related to the normal-state resistivity, R/R-n, varies as (T-c-T)(3/2) with magnetic field.