Growth kinetics of high Tc phase in Bi–Sr–Ca–Cu–O thick films

Abstract

Thick films of Bi–Sr–Ca–Cu–O on (100) MgO substrates have been prepared by the screen printing technique with the starting composition of 1112. The annealing process involves a two-step heat treatment. The first-step temperature is chosen between 874 °C and 898 °C for 45 min followed by slow cooling (2 °C/min) to 864 °C. In the second step, the films are kept at 864 °C for a time varying from 0 to 104 h. The Tc (R = 0) and intensity of the characteristic peaks of the high Tc and the low Tc phases in the x-ray diffraction pattern are found to be dependent on the first-step temperature and the duration of the second step. The process of crystallization and the growth of plate-like grains as a function of annealing time at the second step are studied using Scanning Electron Microscopy (SEM). Kinetics of the growth of the high Tc phase has been explained in terms of a reaction mechanism involving the first and second annealing steps.