The oxalate route to superconducting YBa2Cu3O7−x

Abstract High-Tc superconductors can be easily obtained via the coprecipitation of nitrates and acetates aqueous solutions by oxalic acid. The thermal behavior of the amorphous precipitate was followed by X-ray diffraction. The superconducting YBa 2 Cu 3 O 7−x , orthorhombic phase is obtained upon heating at 860°C. Moreover, a pure tetragonal phase is already formed at temperatures as low as 720°C. This new phase appears to be somewhat different from the usual tetragonal phase. It does not transform into the orthorhombic phase when heated in oxygen between 400°C and 500°C.