X-ray characterization of faults in close-packed structures

Abstract

Single-crystal diffractometer studies of SiC crystals containing a high concentration of stacking faults are described. It is shown that when the faults occur in the course of a solid-state transformation, they are not disturbed randomly and the usual theories of diffraction from randomly-faulted structures cannot be applied to analyze such crystals. Depending on the mechanism of the transformation, a model for non-random faulting has to be developed to calculate the diffraction effects before comparing them with experimental values. Such an analysis provides a means of determining the mechanism of phase-transformation involved. Results of such studies performed on a heavily faulted as-grown 2H SiC crystal and another undergoing a 2H to 6H solid-state transformation are reviewed.