| Abstract: | On the Thermal Dehydration of K2AlF5 · H2O The thermal dehydration of K2AlF5 · H2O was investigated by X-ray diffraction and thermal analysis. Two dehydrat phases were detected. K2AlF5 (II) is orthorhombic (a = 758 pm, b = 1257 pm, c = 1044 pm) and isotypical with α-(NH4)2FeF5 (cis-connected chains). The tetragonal phase is formed by a topotactic mechanism. This phase is instable and tends to rehydrate or to transform into the more stable orthorhombic phase. The irreversible transformation from I into II is connected with an exothermal DTA effect. |
