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

Formation of stoichiometric lead titanyl oxalate from mixed solutions of le ad nitrate and potassium titanyl oxalate at different pH values was investi gated by thermal analysis. At very low pH of approximate to0.45 only lead o xalate was precipitated. Increase in pH from 0.45 to 2.5 did not yield stoi chiometric lead titanyl oxalate. However, at pH 3, the precipitate obtained corresponded to lead titanyl hydroxy oxalate, which on heat treatment at 5 50 degreesC 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. (C) 2001 Kluwer Academic Publishers.