Nanoscale structure and texture of highly anisotropic pyrocarbons revisited with transmission electron microscopy, image processing, neutron diffraction and atomistic modeling

We present a comparative study of the structure and texture at the nanoscale of two well-known high-textured laminar pyrocarbons (PyCs), the rough laminar (RL) and regenerative laminar (ReL) PyCs. Structure is assessed with diffraction data in the reciprocal space (coherence lengths La and Lc), and...

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Bibliographic Details
Published in:Carbon (New York) 2014-12, Vol.80, p.472-489
Main Authors: Farbos, B., Weisbecker, P., Fischer, H.E., Da Costa, J.-P., Lalanne, M., Chollon, G., Germain, C., Vignoles, G.L., Leyssale, J.-M.
Format: Article
Language:English
Subjects:
Computer Science
Cross-disciplinary physics: materials science
rheology
Electron microscopy
Exact sciences and technology
Fullerenes and related materials
diamonds, graphite
Graphene
Heat treatment
Laminar
Materials science
Nanoscale materials and structures: fabrication and characterization
Nanostructure
Other topics in nanoscale materials and structures
Physics
Regenerative
Signal and Image Processing
Specific materials
Surface layer
Texture
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Summary:We present a comparative study of the structure and texture at the nanoscale of two well-known high-textured laminar pyrocarbons (PyCs), the rough laminar (RL) and regenerative laminar (ReL) PyCs. Structure is assessed with diffraction data in the reciprocal space (coherence lengths La and Lc), and in the real space, using a pair distribution function analysis, to finely describe the in-plane features. Texture is characterized from high resolution transmission electron microscopy (HRTEM) images, by analyses of the 002 fringe properties (length and tortuosity) and of new descriptors based on the spatial variations of local orientations, allowing the measurement of the average misorientation angle between crystallites. However, the structure and texture of the RL PyC are recovered when the ReL PyC is heat-treated at 1500°C. In addition, atomistic models are generated from HRTEM images and thoroughly validated against structural and textural indicators. The latter, essentially containing three-coordinated atoms arranged in hexagonal rings, show that the materials differ from the way these rings are clustered together in large hexagonal graphene domains and connected by grain boundaries (pentagon/heptagon pairs), interlayer crosslinks (screw dislocations) and hydrogen-saturated edges.
ISSN:0008-6223
1873-3891
DOI:10.1016/j.carbon.2014.08.087