Study of TiO2, SnO2 and nanocomposites TiO2:SnO2 thin films prepared by sol-gel method: Successful elaboration of variable–refractive index systems

Abstract

In this research TiO _2 , SnO _2 and TiO _2 :SnO _2 nanocomposite thin films were fabricated by the sol–gel dip coating technique. The mixture was prepared by varying the molar ratio of SnO _2 to TiO _2 , i.e. TiO _2 :SnO _2 (9:1), TiO _2 :SnO _2 (8:2) and TiO _2 :SnO _2 (6:4)). The obtained samples were characterized by means of the Raman microscopy, Scanning Electron Microscopy (SEM), UV–Vis spectrophotometry and m-lines spectroscopy (Prism coupler). Raman analysis shows that pure TiO _2 and SnO _2 thin films are characterized by the vibrational modes of anatase and rutile cassiterite, respectively. Furthermore, the Raman spectra of the TiO _2 :SnO _2 nanocomposites show the presence of a mixture of anatase and rutile TiO _2 phases. The SEM images reveal that the morphology is clearly modified with SnO _2 content. The ripples in the transmittance spectra decreased with increasing SnO _2 content. Also, the evolution of the optical band gap seems to be consistent with the Raman analysis. A great attention has been paid to the refractive index measurements by the prism coupler technique. In this way, variable–refractive index systems have been successfully obtained using TiO _2 :SnO _2 nanocomposite thin films.

Keywords

• TiO2
• SnO2
• TiO2:SnO2
• sol-gel
• variable-refravtive Index