On the optical, structural, and morphological properties of ZrO 2 and TiO 2 dip-coated thin films supported on glass substrates

Abstract

This article reports the optical and morphological properties of dip-coated TiO 2 and ZrO 2 thin films on soda-lime glass substrates by metal-organic decomposition (MOD) of titanium IV and zirconium IV acetylacetonates respectively. Thermogravimetric and differential thermal analysis (DTA–TG) were performed on the precursor powders, indicating pure TiO 2 anatase and tetragonal ZrO 2 phase formation. Phase crystallization processes took place in the range of 300–500 °C for anatase and of 410–500 °C for ZrO 2. Fourier Transform Infrared Spectroscopy (FT-IR) was used to confirm precursor bidentate ligand formation with keno-enolic equilibrium character. Deposited films were heated at different temperatures, and their structural, optical and morphological properties were studied by grazing-incidence X-ray Diffraction (GIXRD) and X-Ray Photoelectron Spectroscopy (XPS), Ultraviolet Visible Spectroscopy (UV-Vis), and Atomic Force Microscopy (AFM) respectively. Film thinning and crystalline phase formation were enhanced with increasing temperature upon chelate decomposition. The optimum annealing temperature for both pure anatase TiO 2 and tetragonal ZrO 2 thin films was found to be 500 °C since solid volume fraction increased with temperature and film refractive index values approached those of pure anatase and tetragonal zirconia. Conditions for clean stoichiometric film formation with an average roughness value of 2 nm are discussed in terms of material binding energies indicated by XPS analyses, refractive index and solid volume fraction obtained indirectly by UV-Vis spectra, and crystalline peak identification provided by GIXRD.