Single crystal EPR study of VO(II)-doped magnesium potassium Tutton's salt- Part 4

Single crystal EPR studies of VO(II)-doped magnesium potassium Tutton's sal t have been carried out at room temperature. The results indicate that the paramagnetic impurity has entered the lattice, both substitutionally and in terstitially and the maximum hyperfine for the substitutional site along th e a axis corresponds to the minimum hyperfine for interstitial site and vic e versa. The spin Hamiltonian parameters obtained from single crystal data for these sites are: Site 1, g(parallel to) = 1.954(1); g(perpendicular to) = 1.998(1), A(parallel to) = 19.80(2) mT; A(perpendicular to) = 7.61(2) mT ; Site 2, g(parallel to) = 1.997(1); g(perpendicular to) = 1.952(1), A(para llel to) = 7.66(2) mT; A(perpendicular to) = 19.85(2) mT. Superhyperfine fr om ligand protons have been observed at certain orientations for Site 2 imp urity. Powder spectrum shows a set of eight parallel and perpendicular feat ures indicating the presence of only one site and these values matched with Site 1 values. From these observations, it has been concluded that the two vanadyl impurities are approximately at right angles to each other. Coolin g the sample to 77 K does not change the spectra appreciably. The admixture coefficients have been calculated from Site 1 data, which agree well with the reported values. (C) 2000 Elsevier Science B.V. All rights reserved.