EPR STUDY OF VANADYL ION IN COO-CENTER-DOT-PBO-CENTER-DOT-B2O3 GLASSES

Glasses with composition xCoO .(0.4-x)PbO . 0.6B(2)O(3) containing 1.0 mol% and 2.0 mol% V2O5 have been prepared over the range O less than or equal to x less than or equal to 0.20. The electron paramagnetic re sonance spectra of VO2+ of these glasses have been measured in the X-b and (approximate to 9.3 GHz) at room temperature (RT approximate to 30 0 K). Glasses with 1.0 mol% of V2O5 were prepared by melting at 1173 K and 1373 K. Spin Hamiltonian parameters g(parallel to), g(perpendicul ar to), A(parallel to), A(perpendicular to), dipolar hyperfine couplin g parameter, P, and Fermi contact interaction parameter, K, have been calculated. It is found that these parameters are independent of the t emperature of the melt. Values of g(parallel to), P decrease; value of K increases and value of g(perpendicular to), A(parallel to), A(perpe ndicular to) are constant when V2O5 is increased from 1.0 mol% to 2.0 mol% in the binary lead borate glass. g(parallel to), g(perpendicular to), A(parallel to), A(perpendicular to), P and K change from 1.922+/- 0.001 to 1.927+/-0.001, 1.968+/-0.001 to 1.973+/-0.001, (166.9+/-1.0)x 10(-4) Cm-1 to (165.1+/-1.0)x10(-4) Cm-1, (58.8+/-1.0)x10(-4) Cm-1 to (62.6+/-1.0)x10(-4) Cm-1, 117.6x10(-4) Cm-1 to 111.2x10(-4) Cm-1 and 0 .7614 to 0.8270, respectively, showing that tetragonal distortion of t he V4+O6 complex increases with in the CoO:PbO ratio. It is also found that the increase in CoO:PbO ratio results in an expansion of the 3d( xy) orbit of unpaired electrons in the vanadium ion and that the spin Hamiltonian parameters do not depend on the value of theoretical optic al basicity.