Superconducting Transition in Granular Bi-Sr-Ca-Cu-O Superconductors

In this work we study the superconducting transition in the samples containing relatively small granules of high-T$\text{}_{c}$ Bi-Sr-Ca-Cu-O superconductors. The samples were obtained by the glass-ceramic technology. Two-stage character of the superconducting transition was studied. Pairing transition temperature depends on the magnetic field. Coherence transition is very sensitive to the current flowing through the sample, magnetic field and the phase composition and microstructure of the sample. The analysis of superconducting transition by means of the logarithmic derivative of the fluctuation conductivity shows the mesoscopic granularity of the samples.