ONE MAJOR PHASE IN HIGH TC Y-Ba-CU-O DETERMINED BY ELECTRON DIFFRACTION

A major phase in high T_c Y-Ba-Cu oxide with zero resistance at 91K and high volume fraction of diamagnetic superconductive phase has been identified by electron diffraction. It appears to be an orthorhombic twinned structure with a=3.89Å, b=3.82Å and c=11.7lÅ. Some defects were observed by TEM.