Comparative performance of X-ray diffraction and Raman microprobe techniques for the study of carbon materials

This paper compares the information provided by X-ray diffraction and Raman spectrometry in terms of the structural order in a wide set of carbon soli ds. A special emphasis is placed in checking the validity of the commonly u sed formula of Tuinstra and Koenig and establishing the magnitude of errors potentially derived from its application. For this, a total number of 45 c arbon materials aiming to cover the whole spectrum of properties and applic ations of these solids were jointly characterised by X-ray diffraction and Raman microprobe spectrometry. The comparison of d(002) interlayer spacing and the ratio of D to G Raman band intensities allows one to conclude that both techniques are complementary rather than equivalent. The different typ es of factors affecting the D and G band intensities and widths are discuss ed, it being concluded that their contributions are difficult to separate. The overall conclusion is that Tuinstra and Koenig's formula is valid only as a first approximation to L-a values, and that errors as high as 100% are possible, so that, whenever feasible, direct measurement's by XRD are reco mmended.