Physicochemical properties of proton-conducting SmNiO3 epitaxial films

摘要

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 773–973?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.