Effect of Ion Assistance on the Formation of Composite Carbon-Silver Coatings Obtained by Pulsed-Plasma Deposition

We study composite coatings based on amorphous carbon with encapsulated silver nanoparticles, synthesized by pulsed-plasma sputtering in an argon atmosphere. The deposition is assisted by 100-300 eV argon ions using a KLAN-53M source; samples without ion assistance are also prepared for comparison. Transmission electron microscopy, electron diffraction, and characteristic electron-energy-loss spectroscopy are used to analyze the effect of the ion-assistance parameters on silver nanoparticles and the properties of the carbon matrix. The maximum fraction of sp(3)-hybridized atoms in the amorphous carbon matrix is achieved at an assistance energy of 100 eV and a current density of 22 mu A/cm(2), which is due to material densification and the cross-linking of graphite layers by the ion beam at the specified parameters. The effect of ion-induced processes on the size distribution of silver nanoparticles is described. Ion assistance initiates several processes during deposition: defect formation promoting the formation of nucleation centers for particles 3-5 nm in size, surface diffusion enhancing the coalescence of adatoms and nuclei, and the selective sputtering of silver. The combination of these effects leads to the formation of silver particles of two characteristic sizes: 3-5 and 20-30 nm.