Crystal structure of [Rb0.24(H2O)0.76]VO(H2O)(PO4), a new monoclinic variety in the series of layered vanadyl phosphates

The crystal structure of a new monoclinic variety of hydrous rubidium vanadyl phosphate [Rb0.24(H2O)0.76]VO(H2O)(PO4) doped with Al3+ ions is studied by X-ray (R = 0.054) diffraction: a = 6.2655(4) Å, b = 6.2712(3) Å, c = 6.8569(5) Å, β = 107.805(7)°, space group P21/m, Z = 2, and Dx = 2.792 g/cm3. The new phase obtained by the hydrothermal synthesis in the V2O5-Rb2CO3-AlPO4-H2O system has a layer-type structure in which Rb atoms and water molecules are located between layers of vertexsharing [VO5(H2O)] octahedra and [PO4] tetrahedra. Rb intercalates based on VOPO4 · 2H2O are described by general formula [Rbx(H2O)1 − x]V1−xVVxIVO(H2O)(PO4), where x ≤ 0.5, and the amount of reduced vanadium and interlayer water molecules is determined by the amount of introduced rubidium atoms.