STUDY ON THE FORMATION MECHANISM OF SUPERCONDUCTING PHASES DURING ANNEALING OF SPUTTERED BI-SR-CA-CU-O THIN-FILMS

Abstract

In order to understand the formation mechanism of the superconducting phases, amorphous Bi-Sr-Ca-Cu-O films prepared by RF magnetron sputtering were rapidly cooled after various annealing processes. The 2201 phase began to grow at 600-degrees-C and the 2212 phase with c-axis orientation was grown up to 870-degrees-C. Two kinds of needle-like secondary phases which were rich in Ca and Cu were also observed from 870-degrees-C, along with a partial melting in the matrix. After holding at 880-degrees-C and 890-degrees-C for 6 h, the matrix was mostly liquefied and transformed to the 2201 phase after rapid cooling. However, when slowly cooled at 1-degrees-C/min, the 2212 phase with the c-axis orientation was obtained. On the other hand, when slowly cooled after holding at 870-degrees-C for 6 h, the remaining 2212 phase and the co-existing liquid phase within the matrix could also produce the 2223 phase.