Effect of gamma irradiation on internal friction in lithium tetraborate

The effect of gamma irradiation on the mechanical properties of lithium tetraborate Li2B4O7 in the single-crystal and vitreous states is investigated. It is found that, after irradiation of the Li2B4O7 single crystal, the temperature range of the dissipative process initially occurring at 380–420 K becomes broader and the fine structure of the peak in the temperature dependence of the internal friction Q−1(T) undergoes a substantial trans-formation. After irradiation of the vitreous Li2B4O7 sample, the increase in the internal friction, which is characteristic of the onset of the α relaxation in this material, is not observed in the dependence Q−1(T) up to a temperature of 570 K. It is shown that the mechanical properties of the irradiated samples are almost completely recovered after annealing at 570 K for 1 h.