Abstract
Layer growth patters, concentric hexagonal and circular loops, have been observed on the artificial graphite prepared by heat-treatment of carbon black seast 116. Some electron microscope and diffraction data are given. And it is concluded that these patterns are taken as the spiral growth steps, in accordance with the prediction of Frank's theory, expected when some screw dislocation rows emerge on the crystal faces.From the view point of dislocation theory a brief discussion is tried on certain features of graphite. The numerical values of radii of the critical nuclei are calculated 80-270Aring; as well as the supersaturation of vapour pressure 2.5-8%. The step heights in spirals have been estimated to be 150-250A, which may suggest that scores of initial dislocation with unit strength are crowded in the core. of each crystal.A new concepts, termed as “turbinal layer structure”, is proposed to explain the characteristic structure of those crystals which produce circular growth patterns in micrograph and sporty Debye-Scherrer rings, accompanied by ellipses in diffraction diagram.
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