Yttria-stabilized zirconia (YSZ) film produced from an aqueous nano-YSZ slurry: preparation and characterization (original) (raw)
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Matéria (Rio de Janeiro)
In this work, sol-gel/dip-coating process for obtaining yttria stabilized zirconia (YSZ, ZrO 2-8% Y 2 O 3) films deposited onto LSM-YSZ (lanthanum strontium manganite (LSM, La0.7Sr0.3MnO3) mixed with YSZ) with different proportions (20/80, 50/50, 80/20) was investigated. The films were deposited on substrate varying the number of layers deposited. LSM powders were obtained by the combustion method using metal nitrates and urea and YSZ was commercial. LSM-YSZ composite powders were obtained by the solid state method, through ball-milling of a mixture of LSM-YSZ (mass ratio) powder for 4 h with 500 rpm using ZrO2 balls as milling media. For LSM-YSZ substrate a study of sintering temperature was performed, where the optimum sintering temperature for each LSM-YSZ studied proportion was obtained. According to our results, it was found that 1100 ºC is the optimum sintering temperature for 20/80, 950 ºC is the optimum sintering temperature for 50/50 and 900 ºC is the optimum sintering temperature for 80/20 because of the good phase formation. The films were characterized by X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The films showed LSM, YSZ, SrZrO3 and La2O3 phases. Crack-free, homogeneous and well adhered films were obtained with a thickness between 3 and 38 µm. In this work, YSZ films with appropriate thickness were obtained for application as SOFC electrolyte.
On the Properties of Yttria-Stabilized Zirconia Thin Films Prepared by Sol-Gel Method
Materials Science, 2011
The synthesis of nanostructured films of 20 mol% Y2O3 stabilized ZrO2 on corundum (Al2O3) substrates was performed from different sols using dip-coating technique. All obtained samples were repeatedly annealed at 800 °C temperature after each dipping procedure and fully characterized by X-ray diffraction (XRD) analysis. XRD data exhibited that at 800 °C temperature nano-sized Y0.2Zr0.8O2 thin films with cubic (Fm-3m) crystal structure have been formed. The morphological features of obtained coatings were investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The surface tension and hydrophility of the synthesized films were determined by contact angle measurements (CAM).http://dx.doi.org/10.5755/j01.ms.17.2.491
Journal of Power Sources, 2011
Si-diffusion from Si-based substrates into yttria-stabilized-zirconia (YSZ) thin films and its impact on their microstructure and chemistry is investigated. YSZ thin films used in electrochemical applications based on micro-electrochemical systems (MEMS) are deposited via spray pyrolysis onto silicon-based and silicon-free substrates, i.e. Si x N y -coated Si wafer, SiO 2 single crystals and Al 2 O 3 , sapphire. The samples are annealed at 600 • C and 1000 • C for 20 h in air. Transmission electron microscopy (TEM) showed that the Si x N y -coated Si wafer is oxidized to SiO z at the interface to the YSZ thin film at temperatures as low as 600 • C. On all YSZ thin films, silica is detected by X-ray photoelectron spectroscopy (XPS). A particular large Si concentration of up to 11 at% is detected at the surface of the YSZ thin films when deposited on silicon-based substrates after annealing at 1000 • C. Their grain boundary mobility is reduced 2.5 times due to the incorporation of SiO 2 . YSZ films on Si-based substrates annealed at 600 • C show a grain size gradient from the interface to the surface of 3 nm to 10 nm. For these films, the silicon content is about 1.5 at% at the thin film's surface.
A novel strategy for the preparation of yttria-stabilized zirconia powders
Journal of Non-Crystalline Solids, 2011
In the present work, an alternative to the traditional sol-gel method is reported. The gel is deposited on a wide flat glassy surface so that a very thin film of solid is obtained after evaporation of the solvent. The yttriastabilized zirconia powders are recovered by removing the referred film from the glassy surface and subsequent milling. The samples have been characterized by Scanning Electron Microscopy (SEM), nitrogen adsorption at −196°C and Fourier Transform Infrared (FT-IR) spectroscopy. The experimental results show that the 3 mol% yttria-stabilized zirconia (3YSZ) powders prepared by drying of thin films at 100°C exhibit extremely low values of specific surface area and pore volumes. Furthermore, the proportion of solvent or the type of alcohol used in the preparation of the powders play a very important role in the textural properties of the 3YSZ powders. In this connection, for samples prepared by varying the propanol proportion an increase in the volume of this solvent leads to larger values of specific surface area and pore volumes. On the other hand, an increase in the molecular size of the alcohol used as the solvent leads to a noticeable development of the textural parameters.
Journal of Materials Science, 2000
A stable yttria-stabilized zirconia (YSZ) sol has been synthesized by the controlled hydrolysis of zirconium n-butoxide. Acetic acid and nitric acid were used as chelating agent and catalyst, respectively. The addition of acetic acid and increasing the amount of nitric acids to the system significantly enhanced the sol stability. The viscosity of YSZ sol with the concentration less than 0.80 mol/ was independent on the shear rate, whereas those with the concentration over 1.2 mol/ showed shear-thinning behavior. The reduced viscosity of YSZ sol had linear relationship with sol concentration. These rheological behaviors are attributed to the polymeric nature of YSZ sol. XRD diffractograms of calcined YSZ xerogel confirmed that fully stabilized cubic zirconia phase was formed at a temperature as low as 600 • C. Spin coating of YSZ sol on Si substrate followed by heat treatment at 600 • C for 2 h in air produced uniform crack-free YSZ films of 70-135 nm thickness. C 2004 Kluwer Academic Publishers