Observation and recovery of pressure-induced structural damage in the 2223 phase of (Bi,Pb)-Sr-Ca-Cu-O superconductors

Sintered samples of the high-Tc 2223 phase were densified by uniaxial pressing at room temperature. The bulk AC susceptibility was then dominated by a component with Tc ∼ 65K, typically that of the 2212 phase in this system, although this phase was not seen in X-ray diffraction (XRD). Annealing the sample for ∼ 5 min at 860C restored the bulk high-Tc properties. The authors believe that, during pressing, regions consisting effectively of 2212 material were formed on a scale too small to be detected by XRD, yet extensive enough to govern the bulk superconductivity. The rapid healing of the mechanically induced damage supports this interpretation