Phase modification and surface plasmon resonance of Au/WO₃ system

Highlights: • We have investigated the role of gold as catalyst and nucleation centers, for the crystallization and phase modification of tungsten oxide, in Au/WO₃ matrix. • The phase change from triclinic WO₃ to monoclinic W₁₈O₄₉ is found to enhance with gold incorporation. • The surface plasmon resonance is observed in gold/tungsten oxide system with the appearance of an absorption band near the wavelength 604 nm. - Abstract: We report the action of gold as catalyst for the modification of phase from triclinic WO₃ to monoclinic W₁₈O₄₉ and nucleation centre for the formation of W₁₈O₄₉ phase, in gold incorporated tungsten oxide films prepared by RF magnetron sputtering technique. A new band is observed near 925 cm⁻¹ in the Raman spectra of gold incorporated tungsten oxide films which is not observed in the pure tungsten oxide film. The intensity of this band enhances with gold content. A localized surface plasmon resonance (LSPR) band is observed near the wavelength 604 nm in gold incorporated tungsten oxide films. The integrated intensities of LSPR band and Raman band (∼925 cm⁻¹) can be used for sensing the quantity of gold in the Au/WO₃ matrix.