On the charge flow during plastic deformation in rocksalt

In order to find out if the Gyulai–Hartly effect is really an increase of the ionic conductivity, produced by the plastic deformation, as has been accepted so far, the electrical signals associated with micro-indentations on rocksalt single-crystal specimens, to which either no field or a reversible electrical field was applied, have been studied. The technique enables many reproducible indentations to be made on a specimen, giving comparable signals. When the electric field was applied it was found that an interaction exists between the dislocations and the space-charge polarization, but there is no evidence of the production of free carriers; the negative charge transported by the dislocations, the alteration of the space-charge polarization by them, and creep, can account for the observations of Gyulai and Hartly.