Electrical conductivity of Gd-doped ceria film fabricated by aerosol deposition method

Abstract

Gd-doped ceria (GDC) films were deposited on various substrates using aerosol deposition (AD) method in order to determine whether this process is useful for the fabrication of thin (similar to 1 mu m) electrolyte layers. The AD method is attractive because no vacuum equipment or target material is required. Although the AD method utilizes pre-calcined powder for the deposition of film, the particle size and microstructure of films are largely dependent upon the choice of substrate (sapphire, glass, Si-Pt). The film deposited on sapphire substrate had a relatively dense microstructure and the smallest particle size. Total conductivity of film was measured using either in-plane or across-plane mode depending upon the substrate. Across-plane measurement gave a lower conductivity than in-plane measurement, possibly due to the difficulty of current collection or anisotropic microstructure. The magnitude of in-plane conductivity was comparable to the conductivity of a bulk sample, i.e., similar to 1.2 x 10(-3) S/cm at 450 degrees C for the film deposited on sapphire. The activation energy of electronic conductivity at 300-450 degrees C was also similar, similar to 2.23 eV. However, the activation energy of ionic conductivity differed depending upon the substrates: similar to 0.71 eV for the film on sapphire substrate and 0.93-0.94 eV for other films. The Po-2 dependence had a - 1/4 slope, similar to that of bulk or film form of GDC at higher (>500 degrees C) temperature. Overall, the AD method may be useful for the deposition of thin-film GDC since the conductivity was similar with that of film or bulk samples fabricated by conventional methods. (c) 2013 Elsevier B.V. All rights reserved.