A local structural phase transition of VO₂ studied using EXAFS

The local structural properties around a vanadium atom from a VO2 film were quantitatively determined using extended X-ray absorption fine structure (EXAFS) measurements at K edge of vanadium at different temperatures. A VO2 film was synthesized using a DC sputtering deposition. In order to eliminate the model dependence in EXAFS data analysis, we applied the M1-, M2-, and R-phase models to all temperature data. EXAFS revealed that VO2 was in the M2 phase over a wide temperature range from 40 to 100 ^◦C, although the M1 and the R phases were dominant at low and high temperatures, respectively. This result is somewhat in contrast to previous observations.