Neutron diffraction discriminates between models for the nanoarchitecture of graphene sheets in glassy carbon

TB Shiell and DG McCulloch and JE Bradby and B Haberl and DR McKenzie, JOURNAL OF NON-CRYSTALLINE SOLIDS, 554, 120610 (2021).

DOI: 10.1016/j.jnoncrysol.2020.120610

Glassy carbon is a chemically inert, biocompatible, disordered material with the graphene sheet as its basic building block. Structural characterisation techniques have so far been unable to provide definitive distinction between the many proposed models for its structure. Computer based simulation methods have made a step forward by predicting structure from interaction potentials, but the results are sensitive to the choice of the potential. Here we use the white neutron beam of the Spallation Neutron Source at Oak Ridge National Laboratory coupled with the SNAP time-of-flight diffractometer to sample the reciprocal space of glassy carbon and calculate accurate radial distribution functions. From the radial distribution information, we determine graphene sheet dimensions, registration, curvature, and assess defect content to rank the proposed structures in terms of their agreement with experimental data. We find that the recent models derived from empirical potentials give the best agreement.

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