Abstract
The diamond nanowires (DNW) films have been deposited by N2-based microwave plasma enhanced chemical vapor deposition. Hydrogen plasma treatment is carried out on these films for various treatment times which result in microstructural and chemical modification. Morphology of as-grown DNW films resemble symmetry of dense grains composed in nanowires; however the wires break into ultrasmall, randomly distributed spherical shaped grains after 15 minutes of H2 plasma treatment. Transmission electron microscopy depicts that as-grown DNW films mainly consist of diamond nanocrystals with graphitic sp 2 C C bonded grain boundaries. However, the graphitic grain boundaries do not exist after H 2 plasma treatment on DNW films. Raman spectroscopy and near edge X-ray absorption fine structure spectroscopy studies reveal that after H 2 plasma treatment the films possess large fraction of sp 3 C C and C H bonding in the form of trans-polyacetylene symmetry of sp 2 CHx. Interestingly, the friction coefficient of 0.0001 is obtained for the 15 minutes H 2 plasma treated DNW films. Such an extent of low valued friction coefficient is described by the passivation of uncompensated carbon dangling bonds by hydrogen content and adsorption of H 2 O molecules. Furthermore, in low humid atmosphere, the friction coefficient is found to be consistently increased which confirms the insufficient chemical passivation of carbon dangling bonds. © 2013 by American Scientific Publishers.