Thin‐Film Proton BaZr 0.85 Y 0.15 O ₃ Conducting Electrolytes: Toward an Intermediate‐Temperature Solid Oxide Fuel Cell Alternative

A novel method for the preparation of a thin oxidic proton‐conducting electrolyte is presented. This kind of supported film was studied in detail as it is applicable for IT–SOFC, H 2 membranes, and advanced catalytic converters. Thin‐film (∼5 μm) proton‐conducting membranes with the nominal composition BaZr 0.85 Y 0.15 O 3−δ (BZY) were prepared over porous Ni–8YSZ/Ni–BZY substrates by the solid‐state reaction of a gastight 8YSZ layer and a coated BaCO 3 layer. The resulting asymmetric membranes are of a homogeneous composition and are gastight. Indeed, XRD analysis showed a highly crystalline cubic perovskite. The solid‐state reaction promoted the formation of (i) an electrolyte with very fine (∼100 nm) grains and high packing density and (ii) an unexpected porous needle‐like top layer with a nominal composition similar to that of the protonic electrolyte, to which it is intimately attached. The layer morphology, phase distribution, and lattice composition were investigated by EDS–SEM, EDX as well as SIMS. Conduction properties of the protonic material were investigated by DC conductivity of pressed bars under different gas compositions and also by impedance spectroscopy of a supported thin film.