Influence of thermal activation on dislocation inelasticity of LiF crystals with different impurity compositions

The method of double piezoelectric oscillator is used to investigate the influence of thermal activation (293–573 K) on the dislocation inelasticity and dislocation structure of the annealed LiF crystals having different impurity compositions. On curves illustrating the dependence of the internal friction on the strain amplitude δ(ε₀), a peak having a hysteresis nature is established; it is displaced toward smaller ε₀ values with increasing temperature. A subsequent increase in δ(ε₀) after passage of the peak is caused by the processes of dislocation multiplication upon exposure to ultrasound. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 90–96, August, 2008.