SYNTHESIS OF HIGH-PRESSURE PHASES AT ROOM TEMPERATURE, STRUCTURE AND PROPERTIES OF FULLERITE C60

Studies of the structure and properties of C60 fullerite phases, including ultrahard ones, continue to be relevant. Such interest is associated with the need to obtain large-scale samples suitable not only for comprehensive research, but also for expected practical applications. The complexity of the synthesis of such materials stimulates the search for new approaches in the field of materials science of nanostructured carbon materials and technologies for their production. The article describes studies of changes in the structure of C60 fullerite under high pressure at room temperature using microwave acoustics, Raman scattering and high-resolution transmission electron microscopy (HRTEM). To achieve pressure up to 25 GPa, a high-pressure chamber on diamond anvils with a built-in microwave resonator on a longitudinal bulk acoustic wave (BAW-resonator) was used. The Raman spectra of the stressed top of the diamond anvil and fullerite were used to determine both the pressure and the fullerite phase, respectively. The dependence of the relative frequency shift of the control overtone of the BAW-resonator at a frequency of f = 1.3746 GHz on the pressure as the Δf/f(P) was obtained. Features of the Δf/f(P) curve are associated with structural changes in fullerite, in particular, with the transitions of fullerite from the first to the second and from the third to the fourth phases. At a pressure above 18 GPa, a partial transformation into an amorphous ultrahard phase V is detected, in which fullerite has a hardness higher than that of diamond. The results of such methods as Raman, HRTEM and microwave acoustics confirm the stability of phase V at room temperature. The obtained results can be used, with appropriate scaling, to develop a technology for the synthesis of fullerite in the ultrahard phase V under simpler thermodynamic conditions. For citation: Sorokin B.P., Yashin D.V., Ovsyannikov D.A., Popov M.Yu., Kulnitskiy B.A., Asafiev N.O., Blank V.D. Synthesis of high-pressure phases at room temperature, structure and properties of fullerite C60. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2025. V. 68. N 9. P. 66-74. DOI: 10.6060/ivkkt.20256809.10y.