Preparation and properties of Y2O3-doped ZrO2 thin films by the sol-gel process

Y2O3-doped ZrO2 (YZ) thin films were prepared on alumina substrates by the dip-coating process. The dip-coating solution consisted of a homogeneous sol, and was prepared by using the respective chlorides as raw materials, with ethylene glycol, 2-butanol and distilled water as solvents. The thin films containing 0-20 mot % Y2O3 were successfully produced by thermal treatment above 600 degrees C. The characterization for the film preparation was performed by means of thermogravimetric-differential thermal analysis for the thermal analysis, and scanning electron microscopy for the morphological analysis and thickness measurements. The properties of the films were characterized in terms of a study of the crystalline phase, the crystallite size, the microstructure and the electrical conductivity by using X-ray diffraction, scanning electron microscopy and the complex impedance techniques. In all YZ thin films, the tetragonal phase was stable at low temperatures as a result of the crystallite size effect. However, at higher temperatures, the tetragonal phase was transformed into either the monoclinic phase or the cubic phase, depending on the doping concentration. The YZ thin film of 8 mol % Y2O3 content was stabilized to almost cubic phase at 1000 degrees C. Resonable conductivity behaviour at YZ was observed for the YZ thin films. The electrical conductivity of YZ thin films was similar to the values of the sintered body.