Phase Transformations of C₇₀ Fullerite under High Pressure of 6. 5-12. 5 GPa and Temperature 300-1720 K : Comparison with C₆₀

Abstract

High-pressure high-temperature polymerization of C₇₀ fullerite obtained at first time. New crystal structures of rhombohedrally distorted fcc type and bct type are found for the samples quenched after treatment at p = 6. 5-12. 5 GPa and T = 500-900 K. In the temperature range of 900-1720 K a disordered cross-linked layered structures are found. Samples with bct type crystal structure and with disordered structure have hardness in the range of 30-90 GPa and their density varies in the range of 2. 1-2. 8 GPa. These data are compared with the data for materials obtained from C₆₀ fullerite under the same conditions.