INVESTIGATION OF INSTABILITY OF LATTICE OF BI2SR2CACU2OX

Bi2Sr2CaCu2Ox superconductor was studied by differential scanning calo rimetry (DSC) and thermogravimetry (TG) in different atmospheres. It i s discovered that there is a thermal anomaly in the DSC curve, associa ted with a weight loss in the TG curve before the melting of the sampl e. Careful thermal analysis and high temperature X-ray diffraction rev eal that the thermal anomaly and the weight loss show an instability o f the crystalline lattice. By annealing the sample in oxygen and argon , respectively and then by T-C measurement and thermal analysis, the c oincidence of transition temperature with the instability is found. Th e coincidence is further confirmed by Y-doped 2212 phase.