THERMODYNAMICS OF THE HYDROTHERMAL SYNTHESIS OF CALCIUM TITANATE WITH REFERENCE TO OTHER ALKALINE-EARTH TITANATES

A thermodynamic model for hydrothermal synthesis of alkaline-earth titanates has been utilized to predict the optimum conditions for the synthesis of phase-pure CaTiO3. The predictions have been experimentally validated using Ca(NO3)(2) or Ca(OH)(2) as sources of calcium and crystalline or hydrous TiO2 as a source of titanium at moderate temperatures (433-473 K). Practical experimental techniques have been developed to avoid the contamination of the calcium titanate with undesirable solid phases (e.g., calcium carbonate or hydroxide). These conditions were compared with those previously determined for the Ba-Ti and Sr-Ti hydrothermal system.