ESR identification of radiation-induced oxygen vacancy centers in paratellurite

Abstract

The ESR spectrum of paratellurite (\ensuremath{\alpha}-${\mathrm{TeO}}_{2}$) exposed to 1-MeV electron irradiation reveals a single spin-(1/2) defect in eight inequivalent sites with an anisotropic g value close to the free-electron value. Principal g values are 2.0105\ifmmode\pm\else\textpm\fi{}0.0005, 1.9705\ifmmode\pm\else\textpm\fi{}0.0005, and 1.9358\ifmmode\pm\else\textpm\fi{}0.0005. Resolved hyperfine structure is attributed to magnetic isotopes of tellurium in seven different sites neighboring each defect site. The g-value anisotropy together with the hyperfine structure suggest a positively charged, oxygen-vacancy model (${V}_{0}$(bu) with properties intermediate between those of the ${E}_{1}^{\mathcal{'}}$ center in ${\mathrm{SiO}}_{2}$ and the ${F}^{+}$ center in alkaline-earth oxides.