An X-ray test of the polarity of silicon carbide crystals

Silicon carbide is a polar crystal consisting, in all its structural modifications, of identical networks of silicon and carbon atoms mutually displaced along the c axis. Opposite surfaces are formed by either silicon or carbon layers. The sense of the crystallographic polarity may be determined by means of the small X-ray anomalous dispersion effect. In order to minimize the experimental errors a simultaneous reflection technique has been devised using photographic recording. The results are consistent with theory and agree with those given by etching.