Formation of needle shaped twin domains in cordierite: A computer simulation study

Abstract

The formation of needle shaped domains in cordierite is simulated using a simplified two-dimensional computer model with hexagonal symmetry and nonlocal (strain-induced) atomic interactions. Domain walls form along elastically soft directions as expected and sometimes needle domains appear during annealing. During annealing needles are then consumed by the coarsening process or retract into the domains to which they are attached. Needles have rounded, parabolic tips symptomatic of cordierite’s comparatively low anisotropy energy. Needle splitting is not observed but a novel wetting mechanism by which auxiliary domains form at the needle tip is observed. These domains form such as to make a section of the needle tip a strain allowed domain wall and so reduce the bending energies of the domain walls in this region. At higher temperatures, needle domain walls become only poorly orientated along soft directions and needle domains become patchy with blunt tips and increased “wetting” at the needle tips.