A review of Raman spectroscopy of vanadium oxides

Abstract

This review summarizes Raman scattering data for different stable and metastable phases of vanadium oxides. We analyze literature data on crystal structures existing in the binary vanadium‐oxygen system. If available, we combine these data with experimental Raman spectra and relations of vibrational modes with the atomic arrangements and motions in crystals. Further, we employ arc sputtering to produce vanadium oxide films, including α and β‐vanadium, V 14 O 6, VO, V 2 O 3, V 3 O 5, several phases of VO 2, V 6 O 13, V 3 O 7, and V 2 O 5, as confirmed by X‐ray diffraction analysis. All the films are studied using Raman spectroscopy: low‐ and high‐temperature V 3 O 5 and VO x (1.67 < x < 2) are investigated for the first time. We demonstrate that a significant change in the V 3 O 5 spectrum takes place along the phase transition occurring at approximately 140 °C. Moreover, we describe differences between the spectra of VO 2 polymorphs produced without doping impurities, VO 2 (M1), VO 2 (M2), and VO 2 (T). Finally, we analyze conflicting data on V 7 O 16 and V 3 O 7 and provide an explanation of the observed spectra. Overall, 21 spectra are identified for 53 known phases. Our work is aimed at laying the groundwork for easy identification of vanadium oxide phases in thin films, using Raman spectroscopy.