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 °C was stoichiometric triclinic α-CuV 2O6, whereas the material heat treated at 400 °C was an oxygen deficient counterpart of α-CuV2O5, which was CuV2O5.88 obtained from the thermogravimetric data. X-ray absorption near edge spectroscopy confirmed a valence state of +5 for V in α-CuV2O6, whereas a valence state lower than +5 in CuV2O5.88. The symmetrical degree of the [VO6] octahedron in α-CuV2O6 is higher than that of orthorhombic V2O5 and oxygen deficiency CuV 2O5.88. The Raman band of the V-O1 stretching vibration showed a red shift for copper vanadates with respect to orthorhombic V2O5 because of the electrostatic attraction between Cu and O1 atoms. Moreover, the V4+-O1 stretching vibration was observed for oxygen deficient CuV2O5.88.
Bibliographical noteFunding Information:
This work was supported by the Ministry of Information and Communication of Korea [“Support Project of University Information Technology Research Center” supervised by the Institute of Information Technology Assessment (IITA)] and by KOSEF through the Research Center for Energy Conversion and Storage (RCECS), Korea Science and Engineering Foundation (No. 2000-2-30100-012-3). One of the authors, Y. J. Wei, is grateful to Yonsei University and the RCECS for financial support.
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Condensed Matter Physics