Anisotropic Carbon Phases Prepared from Fullerite C70 under High Pressure

Abstract

We present the structural and ultrasonic study of carbon phases prepared by quenching after heating of fullerite C₇₀ in the temperature range 300–1100°C at pressures 4 and 7.5 GPa. The main aspect of the work concerns the structural and elastic anisotropy of samples resulted as consequence of quasi hydrostatic pressure with an additional pressure component along the axis of pressure load. Structural anisotropy correlates with anisotropy of the tensor of effective elastic constants taken for the medium with single axis of anisotropy. Comparison of the data obtained with anisotropy effects, earlier observed in the phases synthesized from C₆₀ in the similar quasi hydrostatic conditions, clarifies the role of non‐spherical symmetry of C₇₀ molecule.