The effect of Au/Ag ratios on surface composition and optical properties of co-sputtered alloy nanoparticles in Au-Ag:SiO2 thin films

Sangpour, P ; Sharif University of Technology | 2009

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  1. Type of Document: Article
  2. DOI: 10.1016/j.jallcom.2009.06.201
  3. Publisher: 2009
  4. Abstract:
  5. Gold-silver alloy nanoparticles with various Au concentrations in sputtered SiO2 thin films were synthesized by using RF reactive magnetron co-sputtering and then heat-treated in reducing Ar + H2 atmosphere at different temperatures. The UV-visible absorption spectra of the bimetallic systems confirmed the formation of alloy nanoparticles. The optical absorption of the Au-Ag alloy nanoparticles exhibited only one plasmon resonance absorption peak located at 450 nm between the absorption bands of pure Au and Ag nanoparticles at 400 and 520 nm, respectively, for the thin films annealed at 800 °C. The maximum absorption wavelength of the surface plasmon band showed a red shift with increasing Au content. XPS results indicated that the alloys were in metallic state, and they had a greater tendency to lose electrons as compared to their corresponding monometallic state. Moreover, the positive and negative shift of the Au(4f) core-level binding energies was observed for low and high Au concentration, respectively. Also a negative shift of the Ag(3d) binding energies was increased by increasing Au concentration. Diffusion of the particles toward the surface by increasing the temperature has also been illustrated by AFM images. Based on AFM observations, we have found that the particle size reduced from 35 to 20 nm by increasing the annealing temperature from 600 to 800 °C, while particle size increased by increasing Au concentration in films. In addition, lateral force microscopy (LFM) analysis showed that the alloy particles were uniformly distributed on the surface. © 2009
  6. Keywords:
  7. Absorption band ; Absorption wavelengths ; AFM image ; AFM observation ; Ag nanoparticle ; Alloy nanoparticle ; Alloy nanoparticles ; Alloy particles ; Annealing temperatures ; Au-Ag alloy nanoparticles ; Bimetallic systems ; Co-sputtering ; Core levels ; Gold-silver alloy ; Lateral force microscopy ; Metallic nanoparticles ; Metallic state ; Negative shift ; Optical absorption ; Plasmon resonance absorption ; Reactive magnetron co-sputtering ; Red shift ; Sputtered alloys ; Surface compositions ; Surface plasmon band ; UV visible absorption spectrum ; XPS ; Absorption ; Alloys ; Atmospheric temperature ; Atomic force microscopy ; Binding energy ; Binding sites ; Concentration (process) ; Gold ; Gold deposits ; Light absorption ; Nanoparticles ; Nuclear energy ; Optical properties ; Particle size ; Plasmons ; Potential energy ; Silicon compounds ; Silver alloys ; Sputter deposition ; Surface diffusion ; Thin films ; Three dimensional ; X ray photoelectron spectroscopy ; Silver
  8. Source: Journal of Alloys and Compounds ; Volume 486, Issue 1-2 , 2009 , Pages 22-28 ; 09258388 (ISSN)
  9. URL: https://www.sciencedirect.com/science/article/abs/pii/S0925838809013565