A number of SiC crystals having extremely large period unit cells and one-dimensionally disordered structures have been studied by x-ray diffraction and lattice imaging in the electron microscope. It has been observed that structures of extremely large periodicities (>100 nm) can be conveniently studied by lattice imaging technique which simply give continuous streaks in their x-ray diffraction patterns. This has been shown in the case of 150R, 150RA, 900R and another structure whosec-repeat period is more than 100 nm. SiC crystals showing streaks alongc*-direction in x-ray diffraction are found to possess either completely ordered structures with extremely large periodicities or non-random disorder.
Volume 42 | Issue 6
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