Tracking competitive lattice distortions in strongly correlated VO2-based systems: A temperature-dependent EXAFS study

Temperature-driven phase transitions of V1−xCrxO2 (with x = 0.00 and 0.007) have been studied by means of vanadium K-edge X-ray absorption spectroscopy between 50 and 350 K. X-ray absorption near-edge structure (XANES) reveals the electronic changes occurring across the metal-insulator transition at ∼350 K. Extended X-ray absorption fine structure (EXAFS) spectroscopy enlightens the modification occuring to the VO6 octahedra across the different monoclinic (M1, M2, M3) and rutile (R) structures. The EXAFS results provide a complete local structural characterization of the competing lower-symmetry phases of the V1−xCrxO2 (with x = 0.00 and 0.007) and shed light on the major role of lattice relaxation energy in the degradation properties of several devices based on the metal-insulator transition.