Control of ceramic powder composition by precipitation techniques

Precipitation of metal salts of polyfunctional carboxylates is being investigated in our laboratory as a generic method for synthesizing ceramic powders with controlled compositions. The composition of powders can be controlled by synthesizing complexes such as barium titanyl oxalate where the Ba:Ti ratio is known to be 1:1. To prepare barium titanyl oxalate, the authors have investigated the reaction of titanyl ammonium oxalate with barium nitrate and barium acetate using hydrochloric and nitric acids to control the pH of the reaction. Similarly, the reaction between ammonium copper oxalate and barium salts produces BaCu(C2O4) · 6H2O, a complex copper salt which could form during the precipitation of Ba, Y, and Cu oxalates. They have also demonstrated that other polycarboxylic acids can be used to quantitatively precipitate precursors for ceramic powders, and prepared barium yttrium cuprate from the precipitate obtained by reacting tartaric acid with a solution of the barium, yttrium, and copper acetates