Graphitization of Glassy Carbon after Compression at Room Temperature

Abstract

Glassy carbon is a technologically important material with isotropic properties that is nongraphitizing up to ∼3000 °C and displays complete or "superelastic" recovery from large compression. The pressure limit of these properties is not yet known. Here we use experiments and modeling to show permanent densification, and preferred orientation occurs in glassy carbon loaded to 45 GPa and above, where 45 GPa represents the limit to the superelastic and nongraphitizing properties of the material. The changes are explained by a transformation from its sp^{2} rich starting structure to a sp^{3} rich phase that reverts to fully sp^{2} bonded oriented graphite during pressure release.

In situ analysis of the structural transformation of glassy carbon under compression at room temperature

“…This most likely suggests a maximum error in pressure at the maximum pressure of a similar percentage. Note that a past study [18] shows that reversibility is maintained to ~35 GPa while compression to above ~45 GPa results in irreversibility. Both, the pan-DAC and the PP-DAC experiment yielded compression well into the irreversibility field.…”

“…We have recently shown [18] using electron microscopy, Raman spectroscopy, and atomistic modeling that after loading GC in a DAC up to 35 GPa, the recovered material (i.e. measured ex situ) is found to retain its tangled nanostructure, including its minority content of sp 3 bonding (∼5%).…”

Plastic Deformation of Single‐Crystal Diamond Nanopillars

“…Intriguingly, mechanical properties of bulk materials can be altered dramatically when the material dimensions are reduced to the micro‐ and the nanoscale as was demonstrated with metals or silica glasses . Of a particular scientific and technological interest, are carbon‐based materials that comprise a variety of allotropes . For example, 1D carbon nanotubes possess extreme stiffness and high tensile strengths of tens of gigapascals, compared to the poor mechanical stability of sp 2 graphite .…”

3D Laser Scribed Graphene Derived from Carbon Nanospheres: An Ultrahigh‐Power Electrode for Supercapacitors

“…Although high‐temperature treatment induces the graphitization of carbon precursors having a fair degree of lattice alignment (soft carbon), the high‐temperature treatment of amorphous carbon would only result in hard carbon, unless catalysis or high pressure is applied . There is great interest to develop simple, catalysis‐free and low‐temperature graphitization methods, such as electrochemical graphitization, and laser scribing graphitization .…”