Internal friction of solid neon and argon films

The internal friction of solid neon and argon films, with thicknesses of several hundred nanometers, was measured at temperatures up to 25% of the triple point temperature, Ttr. At temperatures higher than 0.12Ttr, the internal friction increased strongly, following an Arrhenius law. The activation energy scaled with triple point temperature and was independent of film thickness. The value suggests that lowered energy barriers for dislocation motion enhance the plasticity and give rise to the internal friction peak.