Physicochemical properties of proton-conducting SmNiO3 epitaxial films

Proton conducting SmNiO_(3)(SNO)thin films were grown on(001)LaAlO_(3)substrates for systematically investigating the proton transport properties.X-ray Diffraction and Atomic Force Microscopy studies reveal that the as-grown SNO thin films have good single crystallinity and smooth surface morphology.The electrical conductivity measurements in air indicate a peak at 473 K in the temperature dependence of the resistance of the SNO films,probably due to oxygen loss on heating.A Metal-Insulator-Transition occurs at 373 K for the films after annealing at 873 K in air.In a hydrogen atmosphere(3%H_(2)/97%N_(2)),an anomalous peak in the resistance is found at 685 K on the first heating cycle.Electrochemical Impedance Spectroscopy studies as a function of temperature indicate that the SNO films have a high ionic conductivity(0.030 S/cm at 773 K)in a hydrogen atmosphere.The activation energy for proton conductivity was determined to be 0.23 eV at 473-773 K and 0.37 eV at 773e973 K respectively.These findings demonstrate that SNO thin films have good proton conductivity and are good candidate electrolytes for low temperature proton-conducting Solid Oxide Fuel Cells.