EPR and Optical Absorption Studies of VO2+ Doped Trisodium Citrate Dihydrate Single Crystals

The electron paramagnetic resonance of VO2+ doped trisodium citrate dihydrate (Na3C6H5O7·2H2O) single crystals and powder has been examined at room temperature. The angular variation of the EPR spectra has shown that two different VO2+ complexes are located in different chemical environments, each environment containing two magnetically inequivalent VO2+ sites in distinct orientations occupying substitutional positions in the lattice and showing a very large angular dependence. The crystalline field around the VO2+ ion is nearly axial. The optical absorption spectrum shows three bands, centered at 24631, 16892, and 12195 cm−1. The spin Hamiltonian parameters and the molecular orbital coefficients are calculated from the EPR and optical data, and result are discussed.