By using a fast multi-window nuclear magnetic resonance technique, in situ measurements were made of the mean jump width, x, of mobile dislocations during plastic deformation of single crystals doped with various Ca2+ contents. Together with immobile forest dislocations, the Ca2+ impurities presented additional obstacles to moving dislocations; thus decreasing the value of x. It was found that Ca2+-related obstacles had a markedly non-random distribution, resulting in a correspondingly wide distribution of x-values. The data could be evaluated by using a distribution function with an unusual dependence of the observed fitting parameters upon the Ca2+ content. Quenching the samples led to a more uniform distribution of the Ca2+-related obstacles and resulted in a corresponding narrowing of the distribution function.

In situ NMR Study of Dislocation Motion in Ca2+-Doped NaCl Crystals. K.Michael, O.Kanert, R.Küchler, J.T.M.De Hosson: Solid State Communications, 2004, 129[11], 727-31