Intercalation of Water into Anhydrous Vanadyl Phosphate Studied by the Infrared and Raman Spectroscopies

The course of intercalation of water into alpha 1-VOPO4 and its monohydrate has been studied by infrared and Raman spectroscopy. The mechanism of hydration has been proposed on the base of these measurements. No formation of vanadyl phosphate monohydrate was observed during hydration of the anhydrous form under ambient conditions. The vanadyl stretching band appears to be especially sensitive to atoms coordinated to the vanadium within an octahedral arrangement in the host lattice structure. During the intercalation its position at 1035 cm-1 in the anhydrous form changes to 995 cm-1, typical for mono- and dihydrates. The additional peak at 1017 cm-1 occurring in the initial stages of intercalation has been explained by the random stacking of intercalated and nonintercalated layers in the sample.