Influence of deposition temperature on growth and electrical properties of Gd-doped ceria electrolyte films

Nanocrystalline Gd-doped CeO2 (GDC) ion conductor electrolyte thin films were synthesized by reactive magnetron sputtering on amorphous quartz substrates at different temperatures. The thin films were characterized by X-Ray diffraction, atomic force microscope and alternating current impedance analysis. The results show that the growth orientation of GDC films varies with the deposition temperature from strong (111) texture at 300-400 degrees C to random growth at 500-600 degrees C. Growth morphologies of GDC films also transform from well-oriented big prismatic growth islands to dense small round ones with increase of the deposition temperature. The activation energy (similar to 1.3eV) of GDC films closed to the reported value for the grain boundary conductivity indicates that grain boundary resistance dominates the electrical properties of GDC films. Conductivity varies with grain size of GDC films due to the grain boundary space charge effect, the smaller the grain size, the higher the conductivity and vice versa.