ChemInform Abstract: Chemical Synthesis and Content of Oxygen of the High-Temperature Superconductor YBa2Cu3O7-x.

ChemInform Abstract

Larger quantities (ca. 500 g) of the title ceramic are best prepared by coprecipitation of Y and Cu as oxalates, subsequent addition of Ba acetate and heating to 1225 K under oxygen. Slow cooling under oxygen affords the single-phase title ceramic, which is a superconductor at 106 K with a transition width ΔT_c < 1 K and a critical current density J_c < 200 A/cm² at 77 K. Furthermore, samples are prepared with up to 5% replacement of Y by Gd, Sm, Eu, Nd, Dy, Ho and Tb, which also display superconductivity, though at lower temperatures.