Beyond ?- C3 N4 -Fullerene-like carbon nitride: A promising coating material

• Published in: Journal of vacuum science & technology. A, Vacuum, surfaces, and films Vacuum, surfaces, and films, 2007, Vol.25 (4), p.633
• Main Authors: Neidhardt, Jörg, Hultman, Lars
• Format: Article
• Language: English
• Subjects: TECHNOLOGY; TEKNIKVETENSKAP
• ISSN: 1520-8559; 0734-2101
• DOI: 10.1116/1.2738505

Even though the synthesis of super-hard-crystalline ?- C3 N4 remains elusive, noncrystalline C Nx compounds are of increasing importance owing to their competitive properties. Especially the fullerene-like allotrope of C Nx exhibits outstanding elasticity in combination with low work of indentation. This new class of thin solid film materials is characterized by a microstructure of bent and intersecting basal planes. Substitutional incorporation of nitrogen into the predominantly s p2 hybridized graphitic layer triggers the formation of curvature-inducing pentagons and interplanar cross-links at a much lower energy cost as compared to carbon-only materials. The term "fullerene- like" was coined to reflect the nanometer scale of curved structural units. Thus, fullerene-like C Nx deforms by bond angle deflection and compression of the graphitic interplanar lattice spacing, whereas the superior strength of the s p2 bonds inhibits plastic deformation giving the material an extremely resilient character. The orientation, radius of curvature of basal planes, and density of cross-linking can be adjusted by the synthesis conditions. Here, the existence of significant numbers of precursor molecules is a determining factor. The inherent resiliency of the material in combination with the carbon-based beneficial friction promises to give rise to numerous tribological applications. © 2007 American Vacuum Society.