Formation of onion-like structures from pitch coke under pressure

Carbon structures containing oxygen are promising in regard to their industrial application. In this work, we studied coke pitch produced on the basis of melted coal tar pitch mixed with thermally expanded graphite. A mixture of pitch and foamed graphite was fired and then subjected to high pressure in a diamond anvil cell. The obtained samples were studied by Raman spectroscopy, and scanning and transmission electron microscopy. Two types of onion-like structures were found: dense and loose structures. It is established that the concentration of oxygen in the loose structures reaches 5 atomic percent.