Bi(Pb)系超伝導多結晶薄膜の諸特性と磁電変換効率

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The Bi-Pb-Sr-Ca-Cu-O thin films with different composition were prepared on MgO single crystal (100) by rf magnetron sputtering using multi targets:Bi0.5Pb0. ?? Oz, CaCu0.75Oz, SrCu0.75Ox. The obtained films were two-step-annealed to crystallize. The crystalline phase of the annealed films were greatly depended on the 2nd annealing temperature. Low temperature(about 820°C) annealing films were composed of C-axis orintated low-Tc phase (Bi(Pb)2Sr2Ca1Cu2Ox). The high-Tc phase(Bi(Pb)2Sr2Ca2Cu2Ox) produced by higher temperature annealing and the films annealed at about 840°C contained both of C-axis orientated low-Tc phase and high-Tc phase. Moreover high temperature (about 850°C) annealing films were composed of C-axis orientated high-Tc phase. From the SEM photograhs of the films annealed at low temperature and at high temperature region. the plate-like crystals of low-Tc and high-Tc phase stacked on each other with C-axis orientation (orientation structure). However, the films annealed in temperature region between them were composed of the mixture of the plate-like crystals with C-axis orientation and with almost perpendicular to the substrate (mixed structure). The sensitivity in magnetic field showed low for the films with orientation structure. On the other hand, it showed high for the films with mixed structure. It implied that the weak-link well produced at grain boudary in the mixed structure.
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