Near-Ir Raman Spectroscopy of Graphitic B–C–N Materials

Raman scattering (RS) by graphitic phases BCxN (g-BCxN), obtained by different methods, was studied using an excitation laser operating in the near-IR (NIR) range. With such excitation the most characteristic peaks for g-BCxN are 1300 cm–1 (D-peak) and 1505 cm–1 (G-peak). It is shown that the D- and G-peaks are associated with disordered graphite: the D-peak is observed because the selection rules change, and its intensity is correlated with the size of the graphite cluster sp2 in a polycrystalline graphite; the G-band is associated with thegraphite mode that is RS-active in the E2g plane. The shift of the D-peak in g-BCxN (1300 cm–1 ) as compared with its position in graphite (1355 cm–1 ) can be explained by the positional dispersion of the D-peak with excitation wavelength. The RS line centered at 1260 cm–1, which could be associated with a RS-active mode, is observed only for samples with high crystallinity and for RS spectra obtained at high pressures and high temperatures.