Preparation and characterization of vanadyl phosphates modified with two trivalent metal cations

The layered crystalline solids with the general formula Mx1Mz2(H2O)x+z(VO)1−x−zPO4·nH2O (M1, M2 = trivalent Al, Cr, Fe, Mn; x, z = 0.04–0.15, n = 2–3) were prepared by refluxing V2O5 with aqueous solutions of phosphoric acid and M1 and M2 metal salts. Compounds were characterized by X-ray diffraction (XRD) and thermogrametric and differential thermal analysis (TG-DTA) techniques. The elementary cell of these compounds is tetragonal, with space symmetry group either P4/nmm or P4/n. The dependence of basal spacings on different relative humidities of atmosphere was followed. The hydration water of the as-prepared compounds depends on the nature and amount of the trivalent metals M1and M2.