COMPUTER-SIMULATIONS OF DIFFRACTION EFFECTS DUE TO STACKING-FAULTS INBETA-SIC .1. SIMULATION RESULTS

X-ray diffraction (XRD) patterns from nominally beta-SiC specimens oft en differ from those expected for the cubic crystal structure. These d ifferences include the presence of additional peaks, enhanced backgrou nd intensities, peak broadening, changes in relative peak heights, and shifts in peak positions. It has long been recognized that they are d ue to the presence of stacking faults, and models relating the experim ental observations to stacking fault population have continued to evol ve. The presence and relative magnitude of these features vary among d ifferent beta-SiC specimens. In this work, computer simulations were u sed to show that the variations are closely related to differences in the type and spatial distribution of stacking faults in each specimen. In these simulations, stacking sequences were generated using a selec tively activated 1-D Ising model with a Boltzmann-type probability fun ction for specifying errors, which allows a wide variety of fault conf igurations to be generated, Direct correlations between different feat ures in the XRD data to the underlying fault population are demonstrat ed, which are discussed in this paper. It is also shown that this comp uter model is general, in the sense that many of the models presented in prior work can be interpreted as limiting cases of it.