Raman spectra of ground natural graphite

Abstract

Structural changes in Ceylon natural graphite with grinding were studied by Raman spectroscopy along with X-ray diffraction. The natural graphite shows a single Raman band at 1580 cm⁻¹, but the ground graphite samples exhibit two Raman bands at 1360 and 1620 cm⁻¹ in addition to the 1580 cm⁻¹ graphite band. The 1360 cm⁻¹ band increases in intensity with increasing grinding time, and becomes much stronger than the 1580 cm⁻¹ band after 200-hr grinding. Raman results are compared with structural parameters such as effective Debye parameter and C₀ spacing obtained from X-ray diffraction measurements, and discussed in terms of structural defects introduced into the crystal lattice of natural graphite. A linear relationship was obtained for the ground graphite when the relative intensity of the 1360 cm⁻¹ band is plotted as a function of effective Debye parameter. The slope of the linear plot is different for the ground graphite from that for the graphitized cokes, indicating a difference in the type of structural defects involved.