Vv. Pujar et Jd. Cawley, COMPUTER-SIMULATIONS OF DIFFRACTION EFFECTS DUE TO STACKING-FAULTS INBETA-SIC .1. SIMULATION RESULTS, Journal of the American Ceramic Society, 80(7), 1997, pp. 1653-1662
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.