PREDICTION OF STACKING-FAULTS IN BETA-SILICON CARBIDE - X-RAY AND NMR-STUDIES

The X-ray powder diffraction profiles of SiC were calculated on the ba sis of the matrix intensity equation method in order to investigate th e stacking sequence in beta-SiC powders. In the case of ''reichweite'' R = 4, where R represents the correlation distance over which the occ urrence of a layer type affects the probability of occurrence of a giv en layer, the structural relationship of the stacking sequence among 2 H, 3C, 4H, and 6H polytypes can be discussed. High-resolution solid-st ate nuclear magnetic resonance (NMR) spectroscopy has been used to obt ain the information concerning the different kinds of sites in 2H, 3C, 4H, and 6H polytypes. This approach reveals that it is possible to de termine the amounts of stacking faults and the kinds of stacking modes in SiC by comparing the calculated X-ray powder diffraction profiles and by the simulation of each deconvoluted signal in the NMR spectra. The calculated result indicates that all of the beta-SiC samples used consist; of mainly the beta C type and some amount of the 6H type stac king modes.