On true crystallite thickness and interlayer spacing in graphitic carbons

Abstract

A simple method of analysis is described to determine the true crystallite thickness and the range of fluctuation of the layer spacing in graphitic carbon from results of x-ray diffraction line breadth measurement. This is not a new technique, but its remarkable usefulness in the field of carbon research has not been known widely. By plotting the reciprocal of the crystallite thickness Lc (00l) against the order of diffraction, one can obtain the true crystallite thickness by extrapolation of the curve and the lattice strain from its slope. For pyrolytic graphite it is shown that the true crystallite thickness is very large, being more than several thousand angstroms, even in as-deposited state, though the apparent Lc (002) is much smaller. Graphitization eliminates the strain, thus increasing the apparent crystallite thickness. A tentative equation correlating Lc (002) and the observed layer spacing in graphitic carbons is proposed.