Identification and preparation of single phase 90 K oxide superconductor and structural determination by lattice imaging

We have investigated various compositions of Ba-Y-Cu-O, resulting in the preparation of single phase 90 K superconducting material of composition (Ba0.67Y0.33)CuO3-δ and the identification of the structure of this superconducting phase by lattice imaging as a layered perovskite. The single phase material had a resistive transition with a midpoint at 92 K and a 1.3 K width (10%-90%) as well as a sharp low-field (H = 0.01 Oe) susceptibility transition. © 1987.