liu.seSearch for publications in DiVA
Change search
ReferencesLink to record
Permanent link

Direct link
Growth and structure of fullerene-like CNx thin films produced by pulsed laser ablation of graphite in nitrogen
Show others and affiliations
2002 (English)In: Journal of Applied Physics, ISSN 0021-8979, Vol. 92, no 9, 4980-4988 p.Article in journal (Refereed) Published
Abstract [en]

The growth and structure of fullerene-like CNx films produced by laser ablation of graphite in low pressure nitrogen were investigated. Deposition conditions were selected based on investigations of CN and C-2 concentration at the condensation surface, vibrational temperature of CN radicals, and kinetic energies of atomic and molecular species. Films were characterized with x-ray photoelectron spectroscopy, Raman spectroscopy, high-resolution transmission electron microscopy, nanoindentation, and stress analyses. The nitrogen content in CNx films directly depended on the concentration of CN radicals at the condensation surface. Formation of fullerene-like structures required a high vibrational temperature of these radicals, which was maximized at about 4 eV for depositions at 10 mTorr N-2 and laser fluences of similar to7 J/cm(2). The presence of C-2 had only a minor effect on film composition and structure. Optimization of plasma characteristics and a substrate temperature of 300 degreesC helped to produce about 1-mum-thick solid films of CNx (N/C ratioapproximate to0.2-0.3) and pure carbon consisting of fullerene-like fragments and packages. In contrast to carbon films, fullerene-like CNx films exhibited a high elastic recovery of about 80% in using a Berkovich tip at 5 mN load and indentation depths up to 150 nm. Their elastic modulus was about 160 GPa measured from the unloading portion of an indentation curve, and about 250 GPa measured with a 40 Hz tip oscillation during nanoindentation tests. The difference was related to time dependent processes of shape restoration of fullerene-like fragments, and an analogy was made to the behavior of elastomer polymers. However, unlike elastomers, CNx film hardness was as high as 30 GPa, which was twice that of fullerene-like carbon films. The unusual combination of high elasticity and hardness of CNx films was explained by crosslinking of fullerene fragments induced by the incorporated nitrogen and stored compressive stress. The study demonstrated laser ablation as a viable technique for the growth of fullerene-like CNx films, which may be used as hard protective coatings resisting brittle fracture at high loads and extensive substrate deformations. (C) 2002 American Institute of Physics.

Place, publisher, year, edition, pages
2002. Vol. 92, no 9, 4980-4988 p.
National Category
Engineering and Technology
URN: urn:nbn:se:liu:diva-47845DOI: 10.1063/1.1509106OAI: diva2:268741
Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2016-08-31

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Hultman, Lars
By organisation
The Institute of TechnologyThin Film Physics
In the same journal
Journal of Applied Physics
Engineering and Technology

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 39 hits
ReferencesLink to record
Permanent link

Direct link