1984 Volume 92 Issue 1061 Pages 14-19
Thermal decomposition of barium titanium (IV) bis (oxalate) oxide and the formation of barium titanate have been studied by means of TG, DTA, XRD, GC and IR. The result shows that the formation of BaTiO3 from oxalate is described as follows: BaTiO(C2O4)2⋅4H2O→BaTiO(C2O4)2→BaCO3+TiO2→BaTiO3. It is supposed that TiO2 produced in the process of the decomposition is amorphous and BaCO3 transforms from an amorphous form to an orthorhombic form via a strained cubic form as temperature increases. The formation of BaTiO3 is supposed to take place at a temperature above 720°C by the reaction between BaCO3 (amorphous, strained cubic or orthorhombic) and amorphous TiO2. The activation energy for the formation of BaTiO3 has been calculated to be 46kcal/mol and it is much lower than that of the conventional process (58kcal/mol). The rate-determining step of the formation of BaTiO3 from oxalate is decomposition process of BaCO3, whereas that of the conventional process is diffusion.
