The interplay between grain boundaries and disclinations in condensed matter physics

Abstract

Abstract The concept of grain boundary, much studied for its relationship with dislocation motion in plastic deformation, is here developed and associated with that of disclination. After defining a disclination in terms of a Volterra process, we investigate the nature of the interplay between both, with application to two cases: i) in polycrystals the triple junctions result from the stress free merging of disclinations bordering the incident grain boundaries; the plastic properties of nanocrystals, which cannot be attributed directly to dislocations, are related to these disclinations; ii) in lamellar liquid crystalline phases grain boundaries are often the place not only of dislocations, but also of focal conic domains, a stunning disclination system described by G. Friedel one hundred years ago.