The Bi-Pb-Sr-Ca-Cu-O thin films with various Ca/Sr ratios were prepared by r.f. magnetron sputtering using multi-targets (Bi0.5Pb0.50x, CaCu0.750x, SrCu0.75Ox. The high Tc phase (2223 phase) was obtained by firing these films. The film with the highest Ca/Sr ratio (Ca/Sr > 1.0) produced the largest amount of 2223 phase on firing at 850 °C. The highest Ca/Sr ratio (=1.17) film contained 91% volume ratio of 2223 phase compared with the low Tc phase (2212 phase) after 15 h firing. However, the 2223 phase decreased with increasing long-term firing (65 h). The resistance curve of the film with the highest Ca/Sr ratio fired for 65 h showed tailing, until the temperature fell below 20 K, suggesting that this phenomenon was due to the segregation of excess calcium and copper components around the grain, in the amorphous state.
Polymer Calcium Copper Thin Film Volume Ratio
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