by R. Gago, M. Vinnichenko, H. U. Jäger, A. Yu. Belov, I. Jiménez, N. Huang, H. Sun and M. F. Maitz
Abstract:
The evolution of sp2 hybrids in amorphous carbon (a-C) films deposited at different substrate temperatures was studied experimentally and theoretically. The bonding structure of a-C films prepared by filtered cathodic vacuum arc was assessed by the combination of visible Raman spectroscopy, x-ray absorption, and spectroscopic ellipsometry, while a-C structures were generated by molecular-dynamics deposition simulations with the Brenner interatomic potential to determine theoretical sp2 site distributions. The experimental results show a transition from tetrahedral a-C (ta-C) to sp2-rich structures at ∼500K. The sp2 hybrids are mainly arranged in chains or pairs whereas graphitic structures are only promoted for sp2 fractions above 80%. The theoretical analysis confirms the preferred pairing of isolated sp2 sites in ta-C, the coalescence of sp2 clusters for medium sp2 fractions, and the pronounced formation of rings for sp2 fractions textgreater80%. However, the dominance of sixfold rings is not reproduced theoretically, probably related to the functional form of the interatomic potential used.
Reference:
R. Gago, M. Vinnichenko, H. U. Jäger, A. Yu. Belov, I. Jiménez, N. Huang, H. Sun and M. F. Maitz, “Evolution of sp2 networks with substrate temperature in amorphous carbon films: Experiment and theory”, Physical Review B, vol. 72, no. 1, pp. 014120.
Bibtex Entry:
@article{gago_evolution_2005,
title = {Evolution of sp2 networks with substrate temperature in amorphous carbon films: {Experiment} and theory},
volume = {72},
shorttitle = {Evolution of $s{p}{textasciicircum}{{textbackslash}mathit{2}}$ networks with substrate temperature in amorphous carbon films},
url = {https://link.aps.org/doi/10.1103/PhysRevB.72.014120},
doi = {10.1103/PhysRevB.72.014120},
abstract = {The evolution of sp2 hybrids in amorphous carbon (a-C) films deposited at different substrate temperatures was studied experimentally and theoretically. The bonding structure of a-C films prepared by filtered cathodic vacuum arc was assessed by the combination of visible Raman spectroscopy, x-ray absorption, and spectroscopic ellipsometry, while a-C structures were generated by molecular-dynamics deposition simulations with the Brenner interatomic potential to determine theoretical sp2 site distributions. The experimental results show a transition from tetrahedral a-C (ta-C) to sp2-rich structures at ∼500K. The sp2 hybrids are mainly arranged in chains or pairs whereas graphitic structures are only promoted for sp2 fractions above 80%. The theoretical analysis confirms the preferred pairing of isolated sp2 sites in ta-C, the coalescence of sp2 clusters for medium sp2 fractions, and the pronounced formation of rings for sp2 fractions {textgreater}80%. However, the dominance of sixfold rings is not reproduced theoretically, probably related to the functional form of the interatomic potential used.},
number = {1},
urldate = {2017-07-21},
journal = {Physical Review B},
author = {Gago, R. and Vinnichenko, M. and Jäger, H. U. and Belov, A. Yu. and Jiménez, I. and Huang, N. and Sun, H. and Maitz, M. F.},
month = jul,
year = {2005},
pages = {014120},
file = {APS Snapshot:E:\cmam_papers\files\455\PhysRevB.72.html:text/html;APS Snapshot:E:\Usuarios\Administrator\Zotero\storage\75PAJEKB\PhysRevB.72.html:text/html},
}