Electrical conductivity and infrared absorption of VO 2+ doped alkali halides

Abstract

The electrical conductivity and IR absorption of vanadyl doped alkali halides are reported. In alkali halides vanadyl is found to rotate in the lattice. The electrical conductivity measurements give evidence for the presence of a bound cation vacancy. The energy of association between the impurity and the vacancy is ≈0.2 eV. There is a shift in the “knee” point for different impurity concentrations and in the IR absorption the band intensities of V—O stretching are different for different concentrations of vanadyl. The vibrational frequencies observed in the host lattices are very different from the free vibrations of V—O in VOSO 4. The deviations are explained by considering the molecular orbital picture of vanadyl complexes. The metal-hallide d π  π * overlap is found to be dominant compared to the metal-oxygen d π - p π interaction.