Structural evolution in the graphitization process of activated carbon by high-pressure sintering

Activated carbon was treated at 5 GPa up to 1600 degrees C, and the structural evolution in the graphitization process was investigated. The graphitization temperature is equal to 1200 degrees C at 5 GPa, reflected by X-ray diffraction (XRD) patterns. Honeycomb-like structures in micron scale come into being in the high-pressure sintering temperature range of 1000-1100 degrees C and slice-like structures appear after graphitization. The existence of D and D'lines in the Raman spectra for the graphitized-activated carbon indicates that there are still some disordered structures. The continuous occurrence of variable-range hopping, the approximately linear rho-T relationship, and semimetal conduction mechanism accords with the graphitization process. (C) 2008 Elsevier Ltd. All rights reserved.