Low-itemperature anomalies in plastic flow of high-purity single crystals of LiF (<i>T</i> = 0.55−4.2 K)

Temperature dependences of the critical shear stress and the strain-rate sensitivity of the flow stress are obtained for high-purity LiF at very low temperatures. Thermal insensitivity interval (0.55−2 K) for the above parameters is determined and a considerable temperature dependence of plasticity at higher temperatures is detected, which is typical of thermally activated processes. The threshold temperature decreases slightly with increasing rigidity of the crystal and its prestrain. Basic characteristics of athermal deformation make it possible to attribute it to quantum tunneling of dislocations through Peierls barriers.

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