Fig. 3: Deformation mechanisms of amorphous carbon.
a EELS measurements of the fraction of sp2 bonded carbon atoms in nanopillar (left graph) and in base (right graph); b Raman spectroscopy data before and after compression; c Schematic diagram of energy barriers for elastic loading and unloading; d Engineering stress-strain curve of cyclic compression test. Black curves show the recoverable hysteresis deformation. Blue curves show the non-linear recovery after plastic deformation. Red broken lines show how the slope of unloading curve changes; e Simulated sp2/sp3 fraction of fully dense amorphous carbon. f Simulated stress-strain curve of fully dense amorphous carbon and the snapshots of microstructural evolution during loading and unloading (see also Supplementary Movie 3). Blue-colored and red-colored atoms represent sp2-bonded and sp3-bonded atoms, respectively. Red broken lines in the graph show how the slope of unloading curve changes.
