Thin film multilayers consisting of 9.5 mol-% Y2O3 doped ZrO2 (YSZ) and different rare earth oxides (RE2O3) with RE = Sc and Lu were prepared on (0001) sapphire substrates using pulsed laser deposition (PLD). These geometrically well defined samples serve as model systems for the investigation of structural influences, especially elastic lattice strain, on ionic transport in interfaces between two different materials. The interface density was varied by varying the number of individual layers while keeping the total thickness of the multilayers constant. To influence the grain boundary density of the typically polycrystalline samples, two different deposition rates, 10 Hz and 2 Hz, were used for the preparation of the samples.Structural characterisation of the samples was performed using X-ray diffraction (XRD), scanning electron microscopy (SEM) and (high-resolution) transmission electrons microscopy ((HR)TEM) methods. For the electrochemical characterisation, mainly AC impedance measurements were applied.All multilayer samples were crystalline directly after deposition and exhibit a columnar grain structure. The interfaces between YSZ and the rare earth oxides are sharp. Furthermore, the multilayers are highly textured and show a distinct orientation relationship between the substrate, YSZ and the rare earth oxides. For RE = Sc, the texture is better developed than for RE = Lu.Based on considerations concerning the influence of mismatch induced interfacial lattice strain on ionic transport, a decrease in total conductivity with increasing interface density was expected for RE = Sc, where a compressive lattice strain is present near the interfaces in YSZ. These assumptions could be proved by the electrochemical investigations. For RE = Lu, a small increase of the conductivity was expected because of the small positive misfit between Lu2O3 and YSZ. However, a small decrease was found instead for the samples deposited at 10 Hz.The investigations on samples deposited at 2~Hz result in data being difficult to analyse. Whereas a strong decrease of the conductivity for RE = Sc is in accordance with the expectations, the values obtained for RE = Lu were too scattered to allow a definite interpretation.
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