Sol-gel synthesis and properties of mixed hydrated oxides HxVxW1−xO3·nH2O

Compounds of the general formula H_xV_xW_1−xO₃·nH₂O have been prepared from peroxide solutions using the sol-gel process. Of these compounds, three phases are orthorhombic: WO₃·1.5H₂O (a = 7.68(3) Å, b = 13.81(5) Å, c = 7.39(3) Å), H_0.08V_0.08W_0.92O₃·1.2H₂O (a = 5.208(3) Å, b = 10.607(9) Å, c = 5.079(3) Å), and H_0.17V_0.17W_0.83O₃·1.5H₂O (a = 7.60(3) Å, b = 13.86(5) Å, and c = 7.37(3) Å); and two phases (with x = 0.25 and 0.33; n = 1) are amorphous as probed by X-rays. The thermal properties, IR, and X-ray photoelectron spectra of the compounds synthesized have been studied. The scenario of phase relations of the H₂O-H-WO₃-V₂O₅ system has been proposed.