Fig. 2: Mechanical properties of amorphous carbon nanopillar and its nanoporous structures.

a SEM snapshots of microcompression test of 59% porosity nanoporous carbon nanopillar. \({{{\boldsymbol{\varepsilon }}}}_{{{\bf{p}}}}\) represent plastic strain and \({{{\boldsymbol{\varepsilon }}}}_{{{\bf{e}}}}\) represent elastic strain. (See also Supplementary Movie 1); SEM images of 59% porosity nanoporous carbon nanopillar b before and after plastic deformation, and c after shear fracture; d Representative engineering stress-strain curves; e Young’s modulus as a function of porosity. Error bars represent standard deviation of 64 tests. The inset shows the power law relation between Young’s modulus and relative density; f Fracture strength and yield strength as a function of porosity. Error bars represent standard deviation of 10 tests. The blue color line indicates the magnitude of the Suquet upper bound. The inset shows the power law relation between strength and relative density; g (left) fracture, elastic, and plastic strains as a function of porosity. (Right) fracture, elastic, and plastic strains as a function of pore size. These specimens have the 51% porosity, but different pore sizes: 21.8 ± 3.3 nm (small), 39.4 ± 4.0 nm (medium), and 79.4 ± 10.0 nm (large). Error bars represent standard deviation of 10 tests. The black arrows in both figures show the presence of transition in fracture strain.