The reactivity of the Bi-Pb-Sr-Ca-Cu-O (BPSCCO) superconductors with a number of oxides was studied and found to be dependent on the acidity of the oxides. BPSCCO shows higher tolerance to these oxide additions than YBa2Cu3O7-x(YBCO) due to its more flexible composition and more open structure than YBCO. SiO2, ZrO2and Al2O3react with BPSCCO and depress the Tcto varying degrees, while MgO is soluble up to the level of 10 mol. replacement for CaO. MgO shows no effect on Tcat addition levels as high as 1.25 times that of the CaO content. The nonpoisoning behaviour of MgO is of significant technical importance for thin and thick film processing, single-crystal growth and melt processing. It may also serve as possible centres for pinning the flux lines.
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