EPR study of vanadyl ion in CoO · PbO · B2O3 glasses

Abstract

Glasses with composition x CoO · (0.4 - x )PbO · 0.6B 2 O 3 containing 1.0 mol% and 2.0 mol% V 2 O 5 have been prepared over the range O ≤ x ≤ 0.20. The electron paramagnetic resonance spectra of VO 2+ of these glasses have been measured in the X-band (≈ 9.3 GHz) at room temperature (RT ≈ 300 K). Glasses with 1.0 mol% of V 2 O 5 were prepared by melting at 1173 K and 1373 K. Spin Hamiltonian parameters g | , g ⊥ , A | , A ⊥ , dipolar hyperfine coupling parameter, P , and Fermi contact interaction parameter, K , have been calculated. It is found that these parameters are independent of the temperature of the melt. Values of g | , P decrease; value of K increases and value of g ⊥ , A | , A ⊥ are constant when V 2 O 5 is increased from 1.0 mol% to 2.0 mol% in the binary lead borate glass. g | , g ⊥ , A | , A ⊥ , 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) × 10 −4 Cm −1 to (165.1 ± 1.0) × 10 −4 Cm −1 , (58.8 ± 1.0) × 10 −4 Cm −1 to (62.6 ± 1.0) × 10 −4 Cm −1 , 117.6 × 10 −4 Cm −1 to 111.2 × 10 −4 Cm −1 and 0.7614 to 0.8270, respectively, showing that tetragonal distortion of the V 4+ O 6 complex increases with increase 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 optical basicity.