Rehydration Characteristics of Lithium Aluminium Silicon Hydroxy-Hydrogel

Abstract

Intermediate powder precursors of three different compositions in the system Li₂O-Al₂O₃-SiO₂ were synthesized in the form of gellike mass by wet-interaction technique in an aqueous medium. These intermediate powder precursors were zeolitic type materials, which were found to exhibit dehydration-rehydration behaviour up to considerably high temperatures, thus establishing the fairly high stability of the network forming structure. The substances retained their amorphous character up to around 600°C, the temperature at which the material became completely dehydrated. The rehydration studies of the dehydrated specimens were carried out at different relative humidities. The dehydration-rehydration characteristics revealed the existence of large cavities and channels which hold the water molecules. The skeleton structure that remains after dehydration consists of silica tetrahedra linked to alumina octahedra and alumina tetrahedra. The amorphous character of the material was found to persist up to around 600°C, the temperature at which the structure collapsed.