Analysis of Crystal Structure of an Y-Ba-Cu Oxide

Results of the analyses on crystal structure and chemical composition of dark-green crystals mainly found in an Y-Ba-Cu oxide specimen which shows high- T c superconductivity are reported. Crystal structure is investigated by the electron diffraction method and is determined to be orthorhombic with lattice parameters a =1.22 nm, b =0.561 nm and c =0.714nm, and with a space group Pnma (No. 62) or Pna2 1 (No. 33). Expected d -values are presented and are successfully compared with the X-ray powder diffraction spectrum obtained from this oxide. Chemical composition is analyzed by the EPMA method and is determined to be Y 2 BaCuO 5- y for the oxide.