Under compressive stress, certain so-called "amorphous" carbon coatings will self-organize (self-heal) into graphene matrices. From my experience, these coatings will initially appear amorphous on TEM observation, but closer analysis of the edges reveals they are organized in planar (graphene-like) sheets that will change to graphene over time with compressive stress.
This is a good comment. We have done limited TEM and have not observe the graphetization. As we move forward in this work with our industry collaborators, we will pay attention to this effect.
This effect may be related not only to compression stress but due to heating by e-beam and activation of carbon atoms mobility by electrons and X-rays. Graphite structure thermodynamically is most stable and would form eventually from all carbon allotropes, heating and radiation damage would accelerate transition from amorphous to graphene lattice. Years ago people have obtained merging of carbon nanotube bundles into larger diameter nanotubes during TEM measurements (I think, Terrones group).
Yes Oleg, the TEM e-beam can excite carbon atoms and increase their mobility; this causing effects such as planar graphene sheets (or nanoribbons) curling into CNTs, etc. But the documented process I am describing occurs with compressive stress on the bonds over time.
We did not subject our samples to excessive enough TEM beam heating to induce any such effect. We observed the 2D planar sheet orientation of the samples from the beginning.
You are likewise correct regarding the Third Law of Thermodynamics, in that those carbon atoms inherently desire the most stable (lowest entropy) ground state and given sufficient time, will orient themselves into a perfect hexagonal matrix (graphene/graphite). You just don't want to have to wait for that to happen naturally, as you will be waiting a very long time.
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