High-Tc Hydroxide- and Fluoride-Containing Ceramic Superconductors

Experimental data for maximum T _c , up to 125 K with temperature cycling, are reported with regard to Y-Ba-Cu-O.OH systems. This increase in T _c is presumably associated with structural transition or phase equilibrium for [CuO₆] local octahedra, occupied by hydroxyl or fluorine ions in the oxygen vacancy sites. Possible improvement in T _c using hydroxide ceramic compounds is described briefly.