Effect of postcombustion denitration treatment in Pb-Bi-Sr-Ca-Cu-O ceramic superconductors

Lead-substituted Bi-Sr-Ca-Cu-O ceramic superconductors were prepared using the combustion method. Differential thermal analysis (DTA) of the postcombusted powder showed the presence of residual nitrates. Subsequent modifications to effectively reduce the amount of nitrates required the prolonged exposure of the combustion product to further heat treatment. The denitration treatment was found to raise the volume fraction of the 2223 phase in the samples, but also lowered the T c onset values when performed at higher temperatures.