Preparation of YBa2Cu3O7-x by the oxalate coprecipitation method and its powder characterization.

The oxalate coprecipitation method was applied to the preparation of high-Tc superconducting oxide powder. The process of forming the oxide through the pyrolysis and subsequent heat treatment was studied in connection with powder characterization. The oxalate copreciptate, being fine powder with -0.3μm in size, consisted of Y-Ba complex and Cu oxalates. The pyrolysis proceeded mostly by three steps in the order of dehydration, decomposition of Cu oxalate and that of Y-Ba oxalate, resulting in CuO and BaC03 phases at 500°C for 2h without changing particle shape. Heat treatment avobe 850°C was favorable to obtain the oxide powder with single phase. Its particles were less than 2μm in size when treated below 925°C and drastically grew to more than 10μm above 950°C with plate-like shape.