• 61.43.Jq;
  • 62.20.F–;
  • 62.40.+i;
  • 63.50.Lm;
  • 78.30.Ly


A synopsis of various photoinduced changes of rheological, mechanical and elastic properties is presented in the first part of the article. After a critical appraisal of a large body of experimental data, it is suggested that the photoviscous effect, that is, the athermal decrease of viscosity of a non-crystalline chalcogenide upon illumination, is the key for a plethora of photoinduced effects reported so far in the literature under different names. Morphic effects (shape or surface morphology) may appear either in the presence or absence of external mechanical stimuli leading to the fabrication of a variety of technologically important photoprocessed structures. A few representative examples of photoplastic effects are described in some detail in the second part of the paper, based on information provided by in situ Raman scattering and nanoindentation experiments.