Orientational (EPR) study of vanadyl ion in potassium hydrogen oxalate lattice

The EPR spectra of VO²⁺ doped KHC₂O₄ crystals revealed two sites with intensity ratio 2:1 and indicated two nearly parallel orientations of the ion in the lattice. On the basis of comparison of the experimentally determined and the calculated direction cosines, only one of the sites could be identified as the substitutional. The other site is suggested to be due to the interstitial occupation of VO²⁺ in the lattice. While the g? tensor is axially symmetric, the à tensor does not show such perfect axial character. The features are explained in terms of the covalency effects arising from hydrogen bonding in the lattice.