Dark-Field Electron Microscopy: II. Studies of colloidal carbon

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Abstract
Several commercial carbon blacks were examined with dark‐field illumination in the electron microscope. Anomalous intensities in the dark‐field images are interpreted as resulting from coherent scattering by parallel layer groups of graphitic planes, which were previously identified by Biscoe and Warren using x‐ray diffraction. The dark‐field micrographs indicate that in a nonreinforcing and a semireinforcing black, the parallel layer groups near the surface of the roughly spherical particles are oriented with their representative vector approximately normal to the surface. No definite evidence was obtainable for such an arrangement in a reinforcing channel black with average particle diameter about 300A. After prolonged heat treatment to the point where graphitization occurs the channel black exhibits numerous diffraction images in darkfield, indicating the presence of crystals with dimensions in the range 20 to 90A.

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