ELECTRICAL EFFECTS AND CRACK NUCLEATION IN ALKALI-HALIDE CRYSTALS.

The results are given of experimental studies of electrical effects observed in alkali-halide crystals under linearly incremental loading and under pulsed loading. It was found that in the initial stage of the loading only an inelastic polarization process is observed, which is attributed to the motion of charged dislocations from surface sources to the central part of the crystal. The nucleation of submicrocracks, caused by the intersection of glide bands, give rise to a elastic polarization component. The emergence of piezoelectric properties is attributed to a dislocation mechanism of charge build-up near submicroscopic defects in the bulk of the specimen.