Synthesis and structural properties of stoichiometric and oxygen deficient CuV2O6 prepared via co-precipitation method

Copper vanadates were synthesized using co-precipitation method. Scanning electron microscopy showed that the crystallinity of the materials increased with heat treatment temperature. X-ray diffraction study showed the material heat treated at 600 DGC was stoichiometric triclinic a-CuV2O6, whereas the material heat treated at 400 DGC was an oxygen deficient counterpart of a-CuV2O6, which was CuV2O5.88 obtained from the thermogravimetric data. X-ray absorption near edge spectroscopy confirmed a valence state of +5 for V in a-CuV2O6, whereas a valence state lower than +5 in CuV2O5.88. The symmetrical degree of the [VO6] octahedron in a-CuV2O6 is higher than that of orthorhombic V2O5 and oxygen deficiency CuV2O5.88. The Raman band of the V-O1 stretching vibration showed a red shift for copper vanadates with respect to orthorhombic V205 because of the electrostatic attraction between Cu and 01 atoms. Moreover, the V4+-01 stretching vibration was observed for oxygen deficient CuV205.88.