The observation of large concentric shell fullerenes and fullerene-like nanoparticles in laser pyrolysis carbon blacks

It has been shown that carbon blacks produced by iron carbonyl-catalyzed CO2-laser pyrolysis of benzene (laser pyrolysis carbon blacks) are characterized by a two-level nanostructure, i.e., they consist of amorphous carbon nanoparticles 30-40 nm in size and fullerene molecules where the fullerenes are predominantly represented by C-60 Heat treatment of the blacks at 3000 degrees C causes restructurization with the appearance of fullerenelike multishell nanoparticles of similar to 20 nm in size, higher fullerenes, and multishell fullerenes. Unlike classical fullerenes, which have a cage structure and are known to have been synthesized in a variety of sizes (C-60, C-70, C-84, C-102, etc.), multishell fullerenes have a cage-inside-cage structure. Direct transmission electron microscopy observation of the cage-inside-cage clusters shows the occurrence of at least three varieties: two-shell 14-Angstrom-sized C-60@C-240, two-shell 20-Angstrom-sized (C-240@C-560), and also three-shell 20-Angstrom-sized (C-80@C-240@C-560).