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AN INVESTIGATION OF CRYSTAL IMPERFECTIONS BY X-RAY DIFFRACTION
BRISTOL UNIV (ENGLAND)
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All sections of the Si crystal showed a complex history of dislocation movement. Dislocation densities varied with distance from the crystal seed from 1000 to 100,000 linessq. cm. Interference of dislocations belonging to 2 or more slip systems gives rise to tangles. Several other reactions between individual dislocations were analyzed. X-ray topographs were made of Ge crystals in the form of tapering wedges to study 1 the contrast of images as a function of thickness, 2 the modulation of intensity of diffracted beams as a function of thickness, and 3 the effect of surface irregularities. Crystals of InSb were examined with dislocation densities ranging from about zero to 10,000 lines sqcm. Progress is reported in heat-treating, etching, and handling of LiF. X-ray topographs of quartz show localized regions of enhanced reflecting power. Work was continued on extending and developing a basic theory of refraction of energy flow and a new approach to the diffraction theory of a distorted crystal.
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