Identification of the High Tc Superconductor in the System Y-Ba-Cu-O

In order to identify the superconducting phase in the Y-Ba-Cu-O system, phase search and electron microscopic study were performed. At least three unknown phases were found in a part of the system. Among these phases, perovskite-related compound (orthorhombic a=3.89, b=3.82, c=11.7 Å or possibly tetragonal a=3.83, c=11.7 Å) is the possible compound responsible for the superconductivity.