The structures of C60-phases, formed by thermobaric treatment:: HREM-studies

The present study was undertaken for determination of microstructures of C-60 phases, formed at different stages of high pressure and high temperature (HPHT) treatment by TEM methods. A sequence of fcc-lattices was found after HPHT treatment at moderate temperature and pressure conditions. Increasing the pressure and temperature values further results in the formation of distorted fcc-phases, explained by the formation of chains of bonded C-60-molecules. Curved carbon structures-ellipsoids and onions with compressed inner layers were observed in C-60-specimens after next stage of thermobaric treatment. Diffraction patterns of the structure, formed after higher parameters, show diffuse arc reflection, separated by a 70 degrees angle. We can conclude, that the materials's hardness increases with increasing temperature and pressure. The hardest material has a structure consisting of onions and 70 degrees disoriented fringes.