Characterisation of nano-crystalline titanium dioxide films grown by atmospheric pressure plasma electrolytic deposition

摘要

A new atmospheric pressure plasma electrolytic process has been developed for the deposition of TiO_2 crystalline thin films on metal substrate. Contrary to the other deposition techniques, the process occurs in a liquid precursor, composed of titanium tetraisopropoxide and absolute ethanol. A plasma discharge is created and confined around the cathode in a superheated vapour sheath surrounded by the liquid phase, inducing the production of a thin TiO_2 coating at the surface of the cathode. Because of the flexibility of the operating parameters, this technology allows the rapid deposition of thin films with a wide range of structural and physical properties. This process enables therefore the production of nano-crystalline titania films with adjustable morphology and structure (anatase, rutile) by adjusting the operating voltage, current intensity, the treatment time and calcination temperature. The analysis of the structure and composition of these TiO_2 coatings have been carried out by Scanning Electron Microscopy, Transmission Electron Microscopy, Raman spectroscopy, X-ray Photoelectron Spectroscopy and X-Ray Diffraction. A thorough study has been performed to understand the influence of the operating parameters on the properties and structure of the coatings.