Shock-induced phase transitions of C70 fullerite

Shock-induced phase transitions of C70 fullerite were studied at the pressure range up to ∼52 GPa with use of recovery assemblies of planar geometry. The starting material consists of two crystalline phases: phase with hexagonal close-packed (HCP) and phase with rhombohedral structure. We have found that C70 fullerite undergoes a series of polymorphic phase transitions in conditions of step-like shock-wave compression. In the specimens, recovered from 9, 14 and 19 GPa, a dominant phase was fullerite C70 with cubic structure. Also, some amount of C70 with HCP structure was observed. The quantity of HCP phase was decreasing with increasing of intensity of shock loading. With further growth of shock pressure, destruction of C70 molecules occurs. In the samples, recovered after shock loading, the main phase was graphite with a low degree of three-dimensional regularity.