Photon-assisted synthesis of ultra-thin yttria-doped zirconia membranes: Structure, variable temperature conductivity and micro-fuel cell devices

We report on the synthesis and functional properties of nanoscale (∼50 nm) dense Y-doped zirconia (YDZ) electrolyte thin films by photon-assisted oxidation of Zr–Y precursor alloy thin films. Crystalline zirconia films with grain size of ∼5 nm were successfully grown at room temperature by oxidation under ultra-violet (UV) photon irradiation. Microstructure of the films was characterized by transmission electron microscopy. The electrochemical conductivity of UV grown YDZ electrolytes was investigated over a broad range of temperatures using Pt electrodes as a function of yttria doping concentration. The slightly lower electrical conductivity in UV grown films at intermediate temperature range (400–550 °C) is consistent with previous reports on oxygen defect annihilation under photo-excitation. Micro-fuel cells utilizing such ultra-thin YDZ membranes yielded ∼12 mW cm−2 power density at 550 °C. The results are of potential relevance in advancing low temperature ultra-thin oxide membrane synthesis for energy applications.