Disorder in ball-milled graphite revealed by Raman spectroscopy

High-energy ball milling has been used to produce nanocrystalline and amorphous structures in nature graphite, but Raman spectroscopy analysis shows that the structure of the amorphous phase produced by ball milling is less disordered than the amorphous structures in ion-beam bombarded graphite and sputtered amorphous carbon. The band intensity ratio (ID/IG) increases first and then drops to 1.1 after 40 h of milling treatment, and remains constant during extended milling up to 100 h. Electron microscopy observation and surface area measurement show that the formation of some nanosized clusters during the extended milling period might be responsible for the less disordered structure in the milled graphite.