Transformations of C60 fullerite under high-pressure high-temperature conditions

Depending on pressure—temperature conditions, fullerite crystals can transform as to the well-known carbon phases, graphite and diamond, and to new metastable crystalline and amorphous modifications. The mechanical properties, density and structural data of the latter are reviewed. It is concluded that the crystalline C₆₀ phases possess mechanical characteristics 2—3 times lower than that for the diamond; amorphous states of carbon with a large share of the sp³ -configurations have mechanical properties close to those of the diamond. The analysis of current literature enables us to conclude that the diamond has the highest elastic moduli among the carbon materials studied up to date.