Inkjet Printed Y-Substituted Barium Zirconate Layers as Electrolyte Membrane for Thin Film Electrochemical Devices

In this work, the inkjet printing of proton conducting Y-substituted barium zirconate (BZY) thin films was studied. Two different kinds of precursor inks, namely a rather molecular BZY precursor solution and a BZY nanoparticle dispersion, have been synthesized and initially investigated with regard to their decomposition and phase formation behavior by thermal analysis, X-ray diffraction, and scanning electron microscopy. Their wetting behavior and rheological properties have been determined in order to evaluate their fundamental suitability for the inkjet process. Crystalline films have been already obtained at 700 °C, which is significantly lower compared to conventional solid-state synthesis. Increasing the temperature up to 1000 °C results in higher crystal quality. Permittivity measurements gave values of around 36 that are in good agreement with the literature while also proving the integrity of the materials. A modification of the as-synthesized BZY stock solution and nanoparticle dispersion by dilution with propionic acid improved the jetability of both inks and yielded homogeneous BZY coatings from both inks. In order to study the electrochemical properties of BZY films derived from the two printed inks, BZY coatings on sapphire substrates were prepared and characterized by electrochemical impedance spectroscopy.