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Comparative microstructural analysis of non-graphitic carbons by wide-angle X-ray and neutron scattering

DOI: 10.1021/acs.jpcc.9b03590 DOI Help

Authors: Torben Pfaff (Justus Liebig University) , Felix M. Badaczewski (Justus Liebig University) , Marc Oliver Loeh (Justus Liebig University; Schunk Carbon Technology) , Alexandra Franz (Helmholtz Zentrum Berlin für Materialien und Energie) , Jens-Uwe Hoffmann (Helmholtz Zentrum Berlin für Materialien und Energie) , Manfred Reehuis (Helmholtz Zentrum Berlin für Materialien und Energie) , Wolfgang G. Zeier (Justus Liebig University) , Bernd M. Smarsly (Justus Liebig University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: The Journal Of Physical Chemistry C

State: Published (Approved)
Published: July 2019
Diamond Proposal Number(s): 13560

Abstract: Non-graphitic carbons (NGCs) represent the most abundant class of \(sp^2\)-hybridized carbon materials (coal, char coal, activated carbon, etc.). These carbons consist of small graphene layer stacks possessing significant structural disorder both in the single graphene sheets and the stacking. In this study an advanced evaluation approach for the wide-angle neutron scattering (WANS) was developed, based on the method introduced by Ruland and Smarsly (2002). In particular, we elucidated if and how the enhanced WANS data quality and larger values of the modulus of the scattering vector \(s\)-range affect the accuracy and the values of the size and disorder parameters - being fitting parameters by themselves - in comparison to wide-angle x-ray scattering (WAXS), which is usually performed by laboratory equipment. We find a reasonable agreement for the parameters \(L_\mathrm{a}\) and \(L_\mathrm{c}\), i.e. the lateral dimension and stack height, within the error bars, while for the disorder parameters different results for WAXS and WANS were found, the origin of which is discussed. Thus, this study addresses the general issue of how reliably microstructural parameters can be determined from WAXS/WANS, by fitting simulated WAXS and WANS curves, which are quality-impaired by added Gaussion noise at different levels and cut-off at different \(s\)-values. From this analysis we estimated the minimal data quality required for a reliable NGC microstructural analysis based on WAXS/WANS. As an important finding, these simulations show that typical, standard WAXS laboratory setups are sufficient to provide reliable values for the most relevant structural parameters. Furthermore, pair-distribution function (PDF) analyses were performed on WAXS data obtained from a Synchrotron facility. Comparing PDF and WAXS/WANS fitting analysis thus suggests the presence of small highly ordered oligoaromatic domains embedded in the larger graphene sheets, questioning the classical view on the NGC microstructure.

Journal Keywords: Diseases and disorders; Layered materials; Carbon; Two dimensional materials; Scattering

Subject Areas: Materials

Instruments: I15-1-X-ray Pair Distribution Function (XPDF)

Added On: 17/07/2019 11:31

Discipline Tags:

Materials Science

Technical Tags:

Scattering Pair Distribution Function (PDF)