Observation of dislocations in non-metallic layer structures

Transmission electron microscopy of thin foils, as developed by Hirsch, Whelan and co-workers¹, has become an important tool in studying the static^1,2 and kinetic³ behaviour of dislocations in metals. Very few observations on non-metals have been published as yet. We have applied this technique to a number of non-metallic layer structures. One has then the advantage that very thin cleavage flakes can easily be prepared and, moreover, that the main glide plane usually coincides with the cleavage plane. In such cases extensive dislocation patterns will appear in the plane of observation. In particular, we have studied in some detail the following substances: bismuth telluride and antimony telluride, graphite, muscovite and talc. A few examples of patterns observed are reproduced in Figs. 1-3.