Effect of high-pressure high-temperature treatment on the structure of a hexagonal modification of fullerite C60

Abstract

Powder X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, and molecular dynamics have been employed to investigate structural transformations in hexagonal and cubic modifications of fullerite C60 after the action of high pressure (4 GPa) within the temperature range 20–1450°C. It has been found that fullerene molecules polymerize to afford polymer structures only in the case of face-centered cubic samples. Under the effect of high pressure and temperature, fullerite C60 with a hexagonal close-packed structure is initially transformed into the cubic modification and, then, forms polymerized structures, which, during an increase in the treatment temperature, become less stable and ordered than the same polymerized structures obtained directly from cubic fullerite C60. X-ray photoelectron spectroscopy measurements suggest deformation of the cages of fullerene molecules in the polymerized structures.