calque

Workshops

Computational Studies of Defects in Nanoscale Carbon Materials

May 11, 2009 to May 13, 2009
Location : CECAM-HQ-EPFL, Lausanne, Switzerland
   EPFL on iPhone
   Visa requirements

Defects as structure-defining features in Fullerene-like Carbon Nitride and Phosphorus-Carbide



Download file

[DOC File - 28.00 KB]

Abstract

Contrarily to most fullerene allotropes, fullerene-like carbon nitride (FL-CNx) can be synthesized in compound form by vapor phase deposition of thin solid films at a relatively low temperature [1]. In FL-CNx, the substitutional N at C sites in graphene layers promotes bending due to incorporation of shapes other than hexagons and cross-linkage, dramatically improving the properties of the CNx.

By developing the Density Functional Theory (DFT)-based Synthetic Growth Concept (SGC) understood as structural evolution by sequential steps where each one is defined by the previous relaxed state, we addressed the defects and structural evolution of FL-CNx [2].

Perceiving the FL solid compounds as an entirely new class of materials, we employed SGC to predict the feasibility of solid phosphorus-carbide FL-CPx. In the case of FL-CPx, phosphorus is seen as an alternative dopant to nitrogen in the graphene network. In comparison with FL-CNx, higher curvature of the graphene sheets and higher density of cross-linkages (some of which with a character of inter-linkages) between them were predicted and explained by stability and prevalence of P-containing tetragon defects. Cage-like and onion-like structures both containing tetragons are determined as typical for FL-CPx [3].

The purpose of the present presentation is to discuss and compare typical defects in FL-CNx and FL-CPx and their essential role as structure-defining features of these compounds [4]. Remarkable agreement of these theoretical results with results from characterization of FL-CNx and (recently deposited by us) FL-CPx will be also commented.



References

[1] L. Hultman, J. Neidhardt, N. Hellgren, H. Sjöström, J.-E Sundgren, MRS Bulletin 28 (2003) 19
[2] G. K. Gueorguiev, J. Neidhardt, S. Stafström, L. Hultman, Chem. Phys. Lett. 410 (2005) 228
[3] G. K. Gueorguiev, A. Furlan, H. Högberg, S. Stafström, L. Hultman, Chem. Phys. Lett., 426 (2006) 374
[4] G. K. Gueorguiev, E. Broitman, A. Furlan, S. Stafström, L. Hultman, manuscript in final stage of preparation