Phase transitions as studied by electron microscopy and electron diffraction

Electron microscopy is used to study phase transitions and pretransitional phenomena in a few different solids. In situ electron microscopy observations of specimens mounted in a microfurnace at temperatures in the vicinity of the transition temperature often reveal instabilities. Recent results are presented on some alloy systems and on a Cu-intercalated layer structure. A movie on the α to #betta# phase transition in quartz shows evidence for domain mobility and domain wall functions at temperatures close to the phase transition temperature of 573deg C. Particularly striking are the low frequency oscillations of interfaces which could be identified as Dauphine twin boundaries. A crystallographic model is proposed of changes in the atomic configuration involved in the successive stages of the transformation process. (author)