TEM OBSERVATION OF DISPROPORTIONATION OF MULLITE AND SILLIMANITE UNDER SHOCK COMPRESSION

Abstract

Shock recovery experiment on sillimanite was conducted using a two‐stage light‐gas gun to clarify origin of the peculiar nano‐frgmentation observed in mullite. Recovered sillimanite was examined by X‐ray powder diffraction (XRD) and transmission electron microscopy (TEM). Shock recovered sillimanite showed amorphization by XRD measurements as seen in mullite. However, microtexture observed by TEM showed characteristic planar deformation structures and following amorphization, which are considerably different from those observed in mullite. Importance of oxygen vacancies in crystal structure of mullite for the nano‐fragmentation was inferred from comparison to the present result on sillimanite.