An energy landscape for carbon network solids

Carbon network solids show a rich diversity with many distinct structural classes. Transitions between classes can be induced by annealing and mechanical compression, frequently with unexpected results. We have constructed an energy landscape based on atomistic simulations that includes both amorpho...

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Bibliographic Details
Published in:Carbon (New York) 2013-11, Vol.63, p.416-422
Main Authors: Powles, R.C., Marks, N.A., Lau, D.W.M., McCulloch, D.G., McKenzie, D.R.
Format: Article
Language:English
Subjects:
Annealing
Carbon
Compressing
Construction
Cross-disciplinary physics: materials science
rheology
Density
Exact sciences and technology
Free energy
Fullerenes and related materials
diamonds, graphite
Landscapes
Materials science
Networks
Physics
Specific materials
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Summary:Carbon network solids show a rich diversity with many distinct structural classes. Transitions between classes can be induced by annealing and mechanical compression, frequently with unexpected results. We have constructed an energy landscape based on atomistic simulations that includes both amorphous and crystalline bonded networks. The landscape, representing a minimum free energy surface, is constructed as a function of density and the degree of crystallinity and is used to explain experimental observations. We use the landscape to explain: (1) why some carbon structures show full recovery from deformation while others deform permanently, (2) why annealing of non-crystalline materials grown in a low pressure pure carbon vapor quenching process always lead ultimately to graphite and not to diamond and (3) why room temperature compression of graphitic carbons leads to a reversible amorphization. The tetrahedrally bonded amorphous structure is predicted tohave the lowest free energy at sufficiently high pressures and temperatures and therefore is expected to occur as the endpoint of rapidly quenched shock compression processes of carbon structures.
ISSN:0008-6223
1873-3891
DOI:10.1016/j.carbon.2013.07.002