INFLUENCE OF THE ANNEALING PARAMETERS ON THE VOLUME FRACTION OF THE HIGH-TC PHASE IN THE BI-SR-CA-CU-O SYSTEM

The influence of the annealing parameters (time and temperature) on the synthesis of the high critical temperature phase (110 K) of the Bi-Sr-Ca-Cu-O system was investigated using the microwave absorption technique. The experimental results show that, for both annealing temperatures investigated, the volume fraction of the 110 K phase increases with annealing time, goes through a maximum and then starts to drop, approaching zero for very long annealing times. When the annealing temperature is 1148 K, the maximum volume fraction of the 110 K phase is attained after 224 h; for an annealing temperature of 1153 K, the maximum volume fraction is attained after 48 h. The disappearance of the 110 K phase for long annealing times is attributed to the loss of bismuth.