Spectroscopic studies and electrical conductivity behavior of gamma-irradiated Li(2)So(4)-Na(2)So(4) mixed system

The Li2SO4-Na2SO4 mixed system was prepared by the precipitation technique. Electron paramagnetic resonance (EPR) spectra of the gamma -irradiated Li2 SO4-Na2SO4 mixed system were measured at room temperature. Two types of cen ters, A and B, identified as SO3- and SO4-, respectively were studied. The SO3- center is characterized by an intense isotropic signal with a g-value approximate to 2.0029, while the SO4- center appears as a weak and broad si gnal with a g-value of 2.02. Infrared spectra were recorded for unirradiate d and gamma -irradiated samples. A decrease in the intensity of the IR spec tra was observed after irradiation. The electrical conductivity, sigma, was measured for the Li2SO4-Na2SO4 system before and after gamma -irradiation in the temperature range from 30 up to 430 degreesC. A considerable decreas e in the conductivity value accompanied by an increase in the activation en ergy was observed after gamma irradiation. The energy of formation of Frenk el defects was estimated to be 3.2eV. The current-voltage characteristics w ere measured at different temperatures in order to estimate the type of con duction in the samples. Isothermal annealing kinetics were investigated at different temperatures before and after gamma -irradiation.