Hydrothermal dissolution of perovskite (CaTiO3)

Perovskite (CaTiO sub 3 ) has been exposed to hydrothermal chemical attack in aqueous solution. Dependences on temperature (150-250 deg C) and on duration of attack (1-35 days) have been investigated. It was found that a precipitate surface layer was formed. The thickness of this layer ranged from a few monolayers to several hundred nanometres for the least and the most severe hydrothermal conditions, respectively. The composition of the layer, as deduced by surface analytical techniques, suggests that (i) there is congruent dissolution of the perovskite surface, (ii) a TiO sub 2 precipitate layer is formed, and (iii) the presence of silica and CO sub 2 in solution do not appear to substantially affect the mechanism or the rate of dissolution. 15 ref.--AA