ANOMALIES OF CELL PARAMETERS BEFORE SUPERCONDUCTING TRANSITION FOR BISMUTH BASED OXIDE SUPERCONDUCTOR

The results of X-ray diffraction analysis at low temperatures for bismuth-based high-Tc oxide superconductors are reported in this letter. There is no significant structural phase transition during superconducting transition. However, it appears that the cell parameters change anomalously before superconducting transition. This anomalous change in cell parameters is repeated for different bismuth-based high-Tc oxide superconductors.