A new method for characterizing the degree of graphitization of carbon materials by laser Raman spectroscopy

Materials and Structures Laboratory, Tokyo Institute of Technology* Department of Chemical Engineering, Nagoya University**
â—‹Katsumi Suda* Hiromi Ohmiya* Yasuhiro Tanabe** Eiichi Yasuda*

Raman spectroscopy is used for the characterization of the local structures of carbon materials. The degree of graphitization of the materials is usually estimated by the ratio of intensities of D band (1360 cm-1) and G band (1580 cm-1). However, the ratio shows disagreement with powder X-ray diffractometry and depends on the orientation of the sample. In this study, a method to characterize the carbon materials using 2D band (2600-2700 cm-1 ) is investigated.
Raman spectra of highly orientated pyrotytic graphite (HOPG), glassy carbon, non-graphitizable carbon, and so on, were measured using Jobin-Yvon T64000 spectrometer with two different laser excitations (514.5 nm and 647.1 nm). Figure 1 shows the Raman spectra near 2D bands obtained with 514.5 nm excitation. The 2D band of highly graphitized carbon material (such as HOPG) is consisted of two peaks independent with the orientation of the sample, however the band of glassy carbon (GC) consisted of only one broad peak. It indicated that the shape of 2D band spectra reflects the structure of carbon materials and the method can be used to characterize the carbon materials.
The authors acknowledge profs H. Kaburagi and A. Yoshida, Musashi Institute of Technology, for valuable suggestions.