Structural analysis of inclusions in beta silicon carbide whiskers crown from rice hulls

Microcrystalline inclusions in the core of beta-SiC whiskers derived from the pyrolysis of rice hulls have been studied by transmission electron microscopy using conventional bright-field and dark-field imaging. The electron diffraction patterns from the whiskers show extra reflections arising from these inclusions. Dark-field images from these reflections are consistent with the presence of three different variants of inclusions, all of which are oriented with their [001] axes parallel to the heavily faulted [111] growth axis of the whiskers. A structural model for these inclusions is proposed which accounts satisfactorily for the extra reflections in the electron diffraction patterns.