Preparation of single crystals under hydrothermal conditions

Abstract

The capability of preparing carbonates and hydroxides that decompose in air at high temperatures is one of the advantages of hydrothermal reactions as a preparation technique for inorganic materials. In this study, new hydrothermal techniques to prepare single crystals of calcite (carbonate) and hydroxyapatite (hydroxide) were described. For hydrothermal crystal growth of calcite, organic salt solutions were used as a mineralizer for the first time and a solution of ammonium acetate was found to be an excellent mineralizer to obtain high growth rate under mild hydrothermal conditions. Single crystals of hydroxyapatite were prepared from chlorapatite single crystals by ion exchange in alkaline solutions under hydrothermal conditions. The transformation mechanism was explained by dissolution and precipitation of clusters.