Characterization of stabilized ZrO2 thin films obtained by sol-gel method

Abstract

In this work, the characterization of ZrO2 thin films synthesized by the sol-gel method, using two different routes, is presented. Thin films were deposited by dip-coating on glass and Zircaloy-4 (Zry-4) substrates, and heat treated at 500 °C under atmospheric air. Characterization was carried out using X-Ray Diffraction (XRD), Grazing Incidence X-Ray Diffraction (GIXRD), High Temperature X-Ray Diffraction (HT-XRD), Raman Spectroscopy (RS), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Electrical properties of films were studied by conductivity measurements. These films present a thickness of 90 and 200 nm on glass, depending on the synthesis route, and consist of nanocrystals with predominantly tetragonal phase. On coated Zry-4, a non-uniform but dense ZrO2 layer without cracks grows, in contrast with the un-coated Zry-4, where a thicker layer was formed with the presence of micro-fissures. A GIXRD study showed that both tetragonal and monoclinic phases are present in the oxide layer. Conductivity measurements indicated that these films have excellent insulating properties, with resistivity values that exceed 0.5 M Ω.cm below 300 °C. These exceptional properties and the retention of high symmetry phases make this method very attractive for growing good electrical insulator and anti-corrosion ZrO2 thin film coatings.