Effect of Aluminum on the Formation of Silver Metal Quantum Dots in Sol–Gel Derived Alumino-Silicate Glass Film

The effect of aluminum incorporation on silver metal quantum dots formation in the alumino-silicate glass film processed by sol–gel process was investigated. The sol–gel derived glass was coated onto the silica glass plate by spin coating with the mixture solution of tetraethyl orthosilicate (TEOS), C₂H₅OH, H₂O, AgNO₃, Al(NO₃)₃·9H₂O, and HNO₃ with the molar ratios of Ag/Si = 0.12 and Al/Si varying from 0 to 0.12. The formation of the silver metal quantum dots was confirmed by the measurements of the UV/VISoptical spectra, the X-ray diffraction patterns, and the transmission electron microscope images. While the radius of silver metal quantum dots increased with the increase of aluminum concentration, the concentration of the silver metal quantum dots decreased. The formation of the silver metal quantum dots was found strongly suppressed by incorporation of aluminum ions in the glass. The change in the glass structure due to the aluminum incorporation was investigated by the analysis of the Raman spectra. The silver ions in the glass contributed to form stable (Al:Ag)O₄ tetrahedra by pairing with aluminum ions and thus clustering of silver metal quantum dots was hindered.