Sol-gel preparation and optical properties of amorphous TiO₂·P₂O₅ films

Abstract

The transparent, homogeneous and amorphous TiO₂·P₂O₅ composite films with high TiO₂ content were prepared for the first time by sol–gel dip-coating method. The gel and film were characterised by thermo gravimetric–differential thermal analyser, X-ray diffraction, scanning electron microscope and UV-vis-NIR. The effect of TiO₂ content on the morphological, structural and optical properties of gel and film were investigated. The refractive index, band gap and Urbach energy of the films were calculated. The results show that the TiO₂·P₂O₅ films exhibit high refractive index (>2.0) which is similar to that of TiO₂·P₂O₅ bulk glass with the same composition. With the rising of TiO₂ content, the band gap of the TiO₂·P₂O₅ film decreased while their refractive index and Urbach energy increased. Furthermore, the sol–gel process developed in this study offer an efficient route to for preparation such TiO₂·P₂O₅ films into optical devices.

Keywords:

• Amorphous TiO₂·P₂O₅
• Thin films
• Sol–gel method
• Optical properties

Acknowledgment

This work has been supported by science and technology department of Guizhou province (grant no. SY(2014)3058).