A single crystal EPR study of VO2+ ions doped in Cs2Co(SO4)2•6H2O Tutton salt

EPR spectra of VO2+ ions doped in single crystals of Cs2Co(SO4)(2) . 6H(2)O single crystals have been studied at various temperatures (390-103 K) on X-band frequency. The detailed EPR analysis shows three vanadyl complexes with differing intensities. The g and A tensors are found to be axially symmetric. The intense vanadyl complexes in the lattice are found to occupy the Co2+ substitutional sites, whereas the weak vanadyl complex at the interstitial sites. The optical absorption spectrum at room temperature shows three absorption bands characteristic of VO2+ ions in tetragonal symmetry. By correlating the EPR and optical data, the molecular bonding coefficients and the Fermi contact interaction terms have been evaluated and discussed. The line broadening of VO2+ spectra on cooling the crystal is explained on the basis of spin-lattice relaxation narrowing. The spin-lattice relaxation time for the host Co2+ ions has been estimated at various temperatures. (C) 1997 Elsevier Science B.V.