Systematics in the enthalpies of formation of anhydrous aluminosilicate zeolites, glasses, and dense phases

A wealth of anhydrous zeolitic, glassy and dense aluminosilicate phases (see figure) have varying Al/Si ratios and cation contents. The enthalpies of formation of all these materials can be predicted using data for a few selected phases and crystal chemical systematics. The energy associated with the substitution of silicon by aluminum and a charge balancing cation depends strongly on the ionic potential of the cation but only weakly on the type of framework or whether the material is crystalline or glassy. Data for glasses can be used to estimate thermodynamic parameters for anhydrous zeolites.