The reaction between BaCO
3 and TiO
2 has been studied in air and in CO
2 at 700-1020°C. Several products (Ba
2TiO
4, BaTiO
3, BaTi
3O
7, and BaTi
4O
9) were obtained when the mixtures of BaCO
3 and TiO
2 were heated in air, but, under the CO
2 atmosphere of 300-700mm Hg, BaTiO
3 with very small amounts of BaTi
3O
7 was observed.
The kinetics of the reaction between BaCO
3 and TiO
2 under the CO
2 atmosphere of 500mm Hg were studied. The process of the reaction is composed of two steps, i.e. a phase boundary reaction followed by a subsequent diffusion process. The kinetic data can be expressed reasonably by the first-order equation for the earlier stage, and by Tamman's equation for the later one. The activation energy for the earlier stage of rutile is about 43Kcal/mol. There is a discontinuity at about 830°C in the plotting of log k against l/T for the earlier stage of anatase. The activation energies are about 34 and l6Kcal/mol above and below 830°C respectively. The activation energy for the later stage is about 34Kcal/mol for both anatase and rutile.
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