Microstructure of Nanocrystalline Yttria-Doped Zirconia Thin Films Obtained by Sol–Gel Processing
Abstract:Nano- and microcrystalline yttria-stabilized zirconia (YSZ) thin films with a dopant concentration of 8.3±0.3 mol% Y2O3 were prepared with a variation in grain size by two orders of magnitude. A sol–gel-based method with consecutive rapid thermal annealing was applied to fabricate YSZ films, resulting in about 400 nm YSZ on sapphire substrates. The average grain sizes were varied between 5 nm and 0.5 m by heat treatment in the temperature range of 650°–1350°C for 24 h. High-resolution (HRTEM) and conventional transmission electron microscopy analyses confirmed specimens—irrespective of the thermal treatment—consisting of cubic (c-)ZrO2 grains with nanoscaled tetragonal precipitates coherently embedded in the cubic matrix. Energy-dispersive X-ray spectroscopy and HRTEM on a large number of specimens yielded a homogeneous yttria concentration within the grains and at the grain boundaries with the absence of impurities, i.e. silica at the grain boundaries.
Document Type: Research Article
Affiliations: 1: Laboratorium für Elektronenmikroskopie, Universität Karlsruhe (TH), 76128 Karlsruhe, Germany 2: Fraunhofer-Institut für Silicatforschung ISC, 97082 Würzburg, Germany 3: Institut für Werkstoffe der Elektrotechnik, Universität Karlsruhe (TH), 76128 Karlsruhe, Germany 4: Ernst Ruska-Centrum für Mikroskopie und Spektroskopie mit Elektronen, Forschungszentrum Jülich, 52425 Jülich, Germany
Publication date: July 1, 2008