Polyhedral carbon nanoparticles at high pressures

Abstract

The solid-phase transformations of polyhedral nanoparticles at a pressure of 8.0 GPa and various temperatures have been investigated by X-ray diffraction, small-angle X-ray scattering, and transmission electron microscopy. It has been found that the graphene layers of the inner cavities of polyhedral particles are transformed into onion-like structures at temperatures above ∼1000°C. This transformation gives rise to the formation of hybrid-type sp2 carbon nanoparticles, which combine the outer polyhedral shape with the quasispherical onion-like core. Polyhedral nanoparticles smaller than ∼40 nm are completely transformed into onion-like particles at 1600°C.