Acta Crystallographica Section A Foundations of Crystallography · 1987 · 22 citations · 0 references
Natural SciencesMaterials EngineeringMaterials ScienceCrystal StructureMaterials CharacterizationMaterials ChemistryCrystal SymmetryCrystallographyDefect CharacterizationDefectsX-ray CrystallographyX-ray DiffractionCrystallographic DefectsDefect AnalysisEffective Particle DiameterLine Profile FittingPlanar DefectsPyrolytic GraphiteSingle-crystal Diffraction
A detailed X-ray study of HOPG reveals extensive wings on the 00.l Bragg reflections whose width in a scan normal to 00.l is comparable to the mosaic spread. These wings, which are absent in single-crystal profiles, are attributed to rotational or twist (T) defects between perfect substacks of pyrolyzed graphite. Along 11.l, the twists destroy coherence and produce an effective 'particle-size' broadening. The average substack size, or spacing between T defects, is estimated through profile fitting to be about 110 Å. The lateral extent of T defects is comparable to a mosaic-block size.