Micro-structural Evolution in Processed Graphite

The microstructure evolution of graphite milled in n-dodecane and annealed at 1400 C in argon was investigated by Raman spectroscopy, near edge X-ray absorption fine structure (NEXAFS) spectroscopy and X-ray diffraction line broadening analysis (XRD). During milling, the n-dodecane molecular intercalation resulted in the increase in the interlayer spacing (d₀₀₂). The intercalation facilitated graphite cleavage reducing the average crystallite thickness (L_c ) from 175 nm to 6 nm. The results of carbon X-edge NEXAFS spectroscopy indicated that the pi-electron system of graphite was disturbed during milling. Annealing increased the crystallite thickness to 10 nm, restored the pi-electron system of graphite but produced a number of coiled sheets These results provided strong evidence that the increased energy potential due to presence of local structure defects and modification of graphite pi-electron system provide the driving force for rolling up of thin graphite particles during annealing