Abstract
The first order Raman spectra for benzene-derived vapor-grown carbon fibers prepared with a seeding catalyst method and heat-treated at temperatures between 1800 and 3000°C with a step of 200°C for 30 min. were studied as a function of interlayer spacing d002. The d002 values were obtained as values between 0.3359 and 0.3428 nm. The first order Raman spectrum was measured by a Raman spectrometer equipped with a microscope system. The full width at half maximum intensity of the G band (G-FWHM) and the intensity of the D band relative to the G band (ID/IG) can be related well to d002 for the samples consisting of crystallites having a graphite structure. The values of G-FWHM for VGCF samples can be superimposed as a good fit to the previously obtained plots of G-FWHM against d002 for plane-oriented Kapton carbons having d002 values between 0.3356 and 0.3421 nm, except for plots of VGCFs with different average diameters heat-treated at 2600°C. The plots for the 2600°C-treated VGCFs could be associated with the polygonization observed for VGCFs heat-treated at temperatures above 2600°C with a scanning electron microscope. Other spectroscopic parameters, Raman frequencies for the D, D' and G bands, FWHMs for the D and D' bands and the relative intensity of the D' band to the G band ID/IG are discussed with relation to d002.
