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We have studied losses of microwave electromagnetic radiation in granular amorphous hydrogenated carbon films a-C:H(Co) containing cobalt nanoparticles at cobalt concentrations below the percolation threshold and in the percolation threshold region. The difference between the experimental values of the losses in granular structures sputtered on corundum-based substrates and those on aramide tissues is observed. It is found that this is determined by the difference in localization sizes of cluster electron states in a-C:H(Co) films.We have found that losses grow with increasing concentration of cobalt nanoparticles and with increasing frequency. The frequency dependence of losses is determined by the fast spin relaxation of nanoparticles. The anisotropy of losses in a-C:H(Co) covers on aramide tissues is observed. [ABSTRACT FROM AUTHOR]

Co nanocrystals embedded into a hydrogenated amorphous carbon matrix have been studied. The formation of the nanocrystals has been detected by transmission electron microscopy. The local structure of the nanocrystals was investigated by x-ray absorption fine-structure spectroscopy. We found that in as-deposited samples, Co atoms are predominantly coordinated by carbon with the fraction of Co-Co bonds increasing with an increase in the Co content. In the annealed samples, Co nanocrystals are formed with a characteristic size of 20 nm and with the structural parameters similar to that of bulk Co. About 30% of Co atoms remain bonded to the amorphous carbon matrix in the annealed sample. [ABSTRACT FROM AUTHOR]

a-C:H layers were grown by dc magnetron reactive sputtering of a graphite target in Ar + H[sub 2] plasma. Ellipsometric measurements were carried out and analyzed at a wavelength of 6328 Å for three sets of a-C:H layers with different thicknesses (different sputtering times) on silicon, fused quartz, and glass-ceramic substrates. It was shown that the substrate material had a substantial effect upon a-C:H growth: a-C:H layers on Si substrates were uniform up to ∼7000 Å thickness; for thin layers (<1000 Å) the growth rate was greater on quartz than on Si; the refractive index values of a-C:H were slightly different on quartz and Si substrates (1.60-1.65 and 1.65-1.72, respectively); a-C:H layers on glass-ceramic substrates were not uniform and had variable refractive index. [ABSTRACT FROM AUTHOR]

It was found that the field electron emission from the surface of amorphous hydrogenated carbon is accompanied by the emission of negative ions of hydrogen and hydrocarbons. This ion emission is explained by the formation and degradation of the local surface emission centers. [ABSTRACT FROM AUTHOR]