Preparation of Barium Titanates from Oxalates

The decomposition of mixed barium titanium oxalates was studied by means of various thermochemical as well as spectroscopic methods. Infrared (IR) spectra of the mixed oxalates indicate the existence of an octahedral complex with Ti chelated by oxalate groups. In general, the results of both IR and the thermochemical analyses suggest that the oxalates are first converted to unidentate carbonate, then to ionic carbonate, and finally to mixed oxides of perovskite structure. The decomposition processes were found to depend upon the atmosphere. In the presence of oxygen the stoichiometrically mixed oxalates decompose by forming TiO₂ and BaCO₃ as intermediates. Under vacuum, two routes of decomposition occur in parallel. In one route, TiO₂ and BaCO₃ are formed as intermediates; in the other, partially reduced TiO_x(x < 2) is formed, which further reacts with BaCO₃ to produce also BaTiO₃, CO₂ and CO.