Structural, morphological and electrical characterization of ceria-based nanostructured thin films obtained by ultrasonic spray pyrolysis

Abstract

In this work, the synthesis and the structural, morphological and electrical characterization of Ce1−xSmxO2−δ solid solution, with x=0, 0.10, 0.15, 0.20, 0.25 and 0.30mol, are reported. Nanocrystalline, homogeneous, and adherent samarium doped cerium oxide thin films were deposited onto glass (Pyrex®) substrates by a simple and cost effective ultrasonic spray pyrolysis system, at a low substrate temperature of 450°C and further annealing treatment at 500°C for 2h. For all the samples, X-ray diffraction results showed the formation of single phase and well crystalline thin films, with cubic fluorite type structure. Scanning electron microscopy analyses showed homogeneous surfaces for all the samples; from SEM micrographs crystallite sizes were found to be in the range 23–37nm. From atomic force microscopy, surface roughness in the range of 20–95nm was measured and the formation of smooth films with an average grain size of 45nm was observed. For the best sample in the solid solution, high oxygen ion conductivity of 1.71×10−1Scm−1, at 450°C, was determined by impedance spectroscopy, with an activation energy of 0.93eV. Results suggest that these films may have a potential application as electrolytes in intermediate temperature solid oxide fuel cells, IT-SOFC.