Thermal change of unstable stacking faults in beta-SiC

The thermal change of unstable stacking faults (USFs) in ultrafine and high ly pure beta -SiC powder synthesized by the plasma chemical vapor depositio n (plasma-CVD) method was studied by high-resolution transmission electron microscopy (HR-TEM). The number of USFs, which were frequently observed in as-synthesized powder, decreased at elevated temperatures in an Ar atmosphe re. In contrast, the number of general stacking faults (GSFs) increased wit h decreasing number of USFs. Moreover, a type of stacking fault that was ge ometrically more unstable than USF was observed in the specimen after heat treatment. In the present study, the annihilation process of USFs observed in the specimen before heat treatment is discussed.