Fundamental electronic and structural properties of carbon onions in extreme environments

The purpose of this research is to investigate the fundamental tribological (frictional) and stability characteristics of the fullerene-related nano-materials, carbon onions, which are nested fullerenes of typically 5--10 shells. Due to their distinctive structures, the frictional performance of carbon onions in different surroundings seems to be enhanced compared to those of other nano-materials. The objectives of this research are to: (1) investigate the nanoscopic structural properties of carbon onions using high resolution electron microscopy (HRTEM) including the known structural change from spherical to polygonal as a function of synthesis temperature; (2) investigate the change in the sp2/sp3 ratio as a function of increasing synthesis temperature using electron energy loss spectroscopy (EELS); (3) investigate their oxygen functionalities using Raman spectroscopy; (4) investigate their film stability using scanning electron microscopy (SEM); and (5) assess their tribological performance in different environments using a ball-on-disc tribometer.;The practical merit of this research is to develop an environmentally benign solid lubricant that can be widely used in various applications. Experimental results have shown that these nano-materials have unique structures and an increasing sp2/sp3 bond hybridization ratio as a function of increasing synthesis temperature.