Layered structures of hydrated vanadium oxides. Part 2.—Vanadyl intercalates (VO)xV2O5·nH2O

Abstract

Layered structures of hydrated vanadium oxides V₂O_{5 –δ}·nH₂O have been analysed from X-ray (00l) reflections by the Rietveld method. Vanadyl ions (VO²⁺) were found to exist between V₂O₅ layers yielding the formula (VO)_xV₂O₅·nH₂O (x= 0.10). Three phases appearing in the dehydration process were studied: phase I (14.21 Å, n= 2.30) at room temperature, phase Iα(11.64 Å, n= 1.20) at 70 °C and phase Iβ(10.21 Å, n= 0.45) at 122 °C. The structures are approximated by atomic sheets: two V₂O₅ sheets and an interlayer sheet of VO²⁺ ions and water molecules. The two V₂O₅ sheets form a double-sheet V₂O₅ layer 2.7 Å apart. With the phase transition four interlayer sheets in phase I are contracted into two in phase Iα and then into one in phase Iβ.