LAYERED STRUCTURES OF HYDRATED VANADIUM-OXIDES .2. VANADYL INTERCALATES (VO)XV2O5.NH2O

Layered structures of hydrated vanadium oxides V2O5-delta.nH2O have been analysed from X-ray (001) 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 l (14.21 angstrom, n = 2.30) at room temperature, phase l-alpha (11.64 angstrom, n = 1.20) at 70-degrees-C and phase l-beta (12.21 angstrom, n = 0.45) at 122-degrees-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 angstrom apart. With the phase transition four interlayer sheets in phase l are contracted into two in phase l-alpha and then into one in phase l-beta.