Raman spectroscopic characterization of submicron vapor-grown carbon fibers and carbon nanofibers obtained by pyrolyzing hydrocarbons

摘要

Variations of the properties of submicron vapor-grown carbon fibers (VGCFs) and nanofibers, with diametersaround 0.1-0.2 #mu#m and 80-100 nm, respectively, are observedby Raman spectroscopy as a function of heat-treatmenttemperature. The microstructural evolution strongly depends onthe original properties of the material, such that the main transitiontemperatures associated with the onset for establishing two-dimensional graphene ordering are defined below 1500 beg C forthe nanofibers and 2000 beg C for the submicron VGCFs,respectively. The relative intensities (I_D/I_G) of the as-grownphase for submicron VGCFs and nanofibers are 3.44 and 1.35,while those for the corresponding graphitized samples are 0.393and 0.497, respectively.