pH dependence of formation of stoichiometric precursors for calcium, cadmium and lead titanates - a thermal study

Formation of stoichiometric M[TiO(C2O4)(2)] x H2O where M= Ca, Cd and Pb fr om mixed solutions of Ca(NO3)(2), Cd(NO3)(2) and Pb(NO3)(2) with potassium titanyl oxalate were investigated at different pH values and the precipitat es obtained were studied by thermogravimetric and differential thermal anal ysis techniques. Stoichiometric phases of Ca[TiO(C2O4)(2)]6H(2)O, Cd [TiO(O H)(2)C2O4] 4 H2O and Pb [TiO(OH)(2)C2O4] 4 H2O resulted from precipitates o btained at pH=2.5 for Ca, pH=7.0 for Cd and pH=3.0 for Pb systems, while mi xed phases resulted from precipitates at other pH values, pH dependence on formation of stoichiometric precursor phases was found to be crucial in all the three systems.