Determination of crystallite size in polished graphitized carbon by Raman spectroscopy

A series of polished and unpolished sp(2)-nanostructured carbons "nanographites" obtained from the pyrolysis of various precursor types have been systematically studied by both Raman spectroscopy and x-ray diffraction. The ratio between the intensities of the disorder-induced D band and the first-order graphite G band (I-D/I-G) commonly used up to now to estimate the "crystallite" diameter L-a displays, in the case of polished graphitized sp(2) carbons, clear spatial heterogeneities and can lead to the overestimation of the intrinsic structural disorder. The full width at half maximum of the G band, which is shown to be insensitive to the polishing process, exhibits a linear dependence on the mean "crystallite" diameter [FWHM(G) = 14 + 430/L-a] and therefore can be used for an accurate structural characterization of these nanographites.