pH dependent coprecipitated oxalate precursors: a thermal study of lead titanate

Formation of stoichiometric lead titanyl oxalate from mixed solutions of lead nitrate and potassium titanyl oxalate at different pH values was investigated by thermal analysis. At very low pH of ≈0.45 only lead oxalate was precipitated. Increase in pH from 0.45 to 2.5 did not yield stoichiometric lead titanyl oxalate. However, at pH 3, the precipitate obtained corresponded to lead titanyl hydroxy oxalate, which on heat treatment at 550°C for 1 h yielded phase pure PbTiO3. Precipitation at pH 9 showed persistence of oxalate as an impurity. Mixed hydroxides of Pb and Ti with no traces of oxalate impurity occurred at pH 10.5.