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Investigation of Palladium Growth on Nanostructured Tungsten Oxide Films

Tahmasebi Garavand, Nemat | 2008

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 39042 (04)
  4. University: Sharif University of Technology
  5. Department: Physics
  6. Advisor(s): Mahdavi, Mohammad; Iraji Zad, Azam
  7. Abstract:
  8. We have studied making and characterization of gasochromic thin films that are used as gas sensors. Gasochromic films consist of an electronchromic layer and a catalyst layer. Addition of palladium to the surface , increased the sensitivity and decreased the working temperature. The used electrochromic layer was tungsten oxide. WO3 films were fabricated by (PLD) method. The substrates were slide glasses. Structure, morphology and composite of tungsten oxide and optical property of films depend on condition of deposition. The pressure of oxygen gas in chamber and temperature of substrate are two factors that can affect in deposition. We can make layers with different morphology by variation of this condition. We investigate the growth of palladium particles on the surface of tungsten oxide by using electroless technique. This particles act as catalyst on the surface. The results show that the growth of palladium particles on the tungsten oxide films depends on morphology of the surface. Palladium particles grow uniformly on the less roughness surface. Response time of different samples of (Pd/WO3) is measured with hydrogen gas. The results show that the samples deposited on substrate with temperature more than room temperature in the presence of oxygen gas have better transparency compared to other samples. Then PdCl2 is used instead of Pd as catalyst on the tungsten oxide. Gasochromic response shows that samples are made by this method have response time and suitable reversibility. In this method the morphology of tungsten oxide film does not have high effect on the gasochromic response
  9. Keywords:
  10. Tungsten Oxide ; Palladium ; Pulsed Laser Deposition (PLD) ; Electroless ; Gasochromic

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