A model was developed in order to explain the high-temperature dependence of the plastic flow stress of highly covalent crystals of -Al2O3, Si and GaAs. The model assumed the existence of high and steep Peierls potentials which were of the form: Px2 + Qxn (n > 2) for x-values of less than a/2, where a was the period. The kink pair formation energy was deduced from the elastic interaction energy of a trapezoidal kink pair. The results predicted the occurrence of narrow and abrupt kink pairs. The activation energy which was deduced explained the linear decrease in flow stress with temperature. The results suggested that kink pair formation was the rate-controlling process for dislocation motion in covalent crystals.

T.Suzuki, H.Koizumi, H.O.K.Kirchner: Philosophical Magazine A, 1995, 71[2], 389-97