Thermodynamic carbon onions

The question of the thermodynamic stability of carbon onions has been subject to controversial discussion ever since their discovery. Some groups postulate them to be the thermodynamically most stable phase for this size of particles, while... 

Other authors, on the contrary, postulate the spherical carbon onions to be extremely unstable at least upon observation (not irradiation ) in the HRTEM, so they would retain their ball shape only at sufficient electron intensity. They decompose into unordered graphitic material inward from the outer shell. The instabihty is attributed to the system being far from thermodynamic equihbrium. The electron radiation maintains a steady state of onion formation and decomposition balancing each other. When it stops, the structure will tend toward equilibrium. Thus, carbon onions are considered a high-energy modification of carbon in this case. 

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