Spectroscopic studies and electrical conductivity behavior of γ-irradiated Li2SO4—Na2SO4 mixed system

Abstract

The Li2SO4—Na2SO4 mixed system was prepared by the precipitation technique. Electron paramagnetic resonance (EPR) spectra of the γ-irradiated Li2SO4—Na2SO4 mixed system were measured at room temperature. Two types of centers, A and B, identified as SO− 3 and SO− 4, respectively were studied. The SO− 3 center is characterized by an intense isotropic signal with a g-value ≈ 2.0029, while the SO− 4 center appears as a weak and broad signal with a g-value of 2.02. Infrared spectra were recorded for unirradiated and γ-irradiated samples. A decrease in the intensity of the IR spectra was observed after irradiation. The electrical conductivity, σ, was measured for the Li2SO4—Na2SO4 system before and after γ-irradiation in the temperature range from 30 up to 430°C. A considerable decrease in the conductivity value accompanied by an increase in the activation energy was observed after gamma irradiation. The energy of formation of Frenkel defects was estimated to be 3.2eV. The current-voltage characteristics were measured at different temperatures in order to estimate the type of conduction in the samples. Isothermal annealing kinetics were investigated at different temperatures before and after γ-irradiation.