EPR Spectroscopy of the Mn2+and Cu2+Centres in Lithium and Potassium-Lithium Tetraborate Glasses

Abstract

The electron paramagnetic resonance spectra of the glasses with Li2B4O7 and KLiB4O7 compositions doped with Mn and Cu were investigated. On the basis of obtained EPR spectra analysis it was shown that the Mn and Cu impurities are incorporated into the glass network as Mn (S5/2, 3d) and Cu (D5/2, 3d) ions. The Mn EPR spectra in the glasses with Li2B4O7 and KLiB4O7 compositions are characterised by the following parameters, measured at T = 300 K: isotropic g-factor (giso = 2.00± 0.05), isotropic hyperfine constant (Aiso = (8.65 ± 0.05) mT) and peak-to-peak linewidth of hyperfine components ∆Bpp = (3.50 ± 0.05) mT. The Cu EPR spectra in the glasses with Li2B4O7 and KLiB4O7 compositions, registered at T = 300 K are characterised by the same g-values (g‖ = 2.34 ± 0.05, g⊥ = 2.06 ± 0.05) and peak-to-peak line width of hyperfine components (∆B‖ pp = (5.11 ± 0.05) mT, ∆B⊥ pp = (1.80 ± 0.05) mT), whereas anisotropic hyperfine constants show some differences (A‖ = (14.28 ± 0.05) mT, A⊥ = (2.34 ± 0.05) mT for glass with Li2B4O7 composition and A‖ = (14.21±0.05) mT, A⊥ = (2.55±0.05) mT for glass with KLiB4O7 composition). The possible local structure of the Mn and Cu centres in the lithium and potassium–lithium tetraborate glass network has been considered.