The grain boundary effect on dysprosium doped ceria

In this work the Pechini method has been employed to obtain 10, 15 and 20 at.% Dy-doped ceria rendering precursors with an average particle size below 50 nanometers. The powders have been compacted and sintered in the temperature range of 1350-1500 degrees C resulting in average grain sizes ranging from 1 to 10 microns. The electrical conductivity has been examined by Electrochemical Impedance Spectroscopy (EIS) and the bulk and grain boundary contributions for the overall conductivity evaluated by means of the brick layer model. Although bulk conductivities for Dy-doped ceria were lower to those reported for Sm and Gd-doped cerias, the overall conductivity using conventional sintering temperatures is rather similar, due to enhanced grain boundary conductivity in smaller grain size samples. The cause of this enhancement is the decrease in the space layer potential, if a Mott-Schottky model is assumed. (C) 2010 Elsevier B.V. All rights reserved.