pH dependent coprecipitated oxalate precursors - a thermal study of barium titanate

Effect of pH on the formation of stoichiometric coprecipitated precursors for BaTiO₃ from potassium titanyl oxalate and barium chloride was investigated in the pH range 2.0 to 10.0. Thermal analysis revealed that barium titanyl oxalate could be obtained only below pH = 3.0. Increase in pH up to 5.0 led to the formation of barium titanyl hydroxy oxalate, while a two phase mixture of barium oxalate and titanyl hydroxide was observed at pH = 7.0 to 10.0. Thermal decomposition of only barium titanyl oxalate yielded stoichiometric BaTiO₃ at 600 °C.