The hydrothermal decomposition of aluminum fluoride trihydrate. Kinetics and mechanism

The hydrothermal decomposition of AlF₃.3H₂O in water suspension was investigated by chemical and X-ray analyses at temperatures ranging from 114 to ca. 143°C. It was found that this process runs from a trihydrate to a monohydrate composition according to a zero order rate equation to give subsequently Al(OH,F)₃.H₂O and β -AlF₃.H₂O direct from solution and α -AlF₃.H₂O by conversion of solid trihydrate. Reactions involved in the process are discussed in detail.