Synthetic Routes to Perovskite Phase Mixed Metal Oxides

We are developing strategies to form single-component precursors to perovskite phase mixed metal oxides where the stoichiometry of the precursor is fixed at the molecular level to be that of the final desired phase. These strategies ean be applied to the formation of perovskite phase thin films. Two such methods are described herein, relying on ester elimination and alcohol elimination reactions. We have found the reaction between lead(II) acetate and titanium(IV) isopropoxide in ethanol results in ligand redistribution at room temperature. Reactions between (β-diketonate)2M(OR)2 where M = Ti, Zr and Sn and lead(II) acetate do not result in any detectable ester elimination under the reaction conditions employed, and this approach was not successful. Alcohol elimination experiments have been explored as an alternative strategy using a bifunctional glycolate ligand. Lead carbonate reacted with glycolic acid to form the corresponding lead glycolate complex Pb(O2CCH2OH)2. This compound reacted with (β-diketonate)2M(OR)2, M = Ti and Sn, to eliminate two equivalents of alcohol and form the corresponding single component (β-diketonate)2M(OCH2CO2)2Pb complexes. These complexes start to thermally decompose at 150°C and loss of weight is complete by 450°C to yield a product whose weight loss corresponds to the formation of PbTiO3 for M = Ti. Bulk thermolysis of a sample of (dpm)2Ti(OCH2CO2)2Pb at 400°C resulted in formation of crystalline perovskite phase lead titanate together with PbO, massicot and α-PbO phases.