Microstructure and ionic conductivity properties of gadolinia doped ceria (GdxCe1-xO2-x/2) electrolytes for intermediate temperature SOFCs prepared by the polyol method

Abstract

Gd0.1Ce0.9O1.95 and Gd(0.2)Cc(0.8)O(1.9) powders were prepared through the polyol process without using any protective agent. Microstructural and physical properties of the samples were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetry (TG) and impedance analysis methods. The results of the thermogravimetry/differential thermal analysis (TG/DTA) and XRD indicated that a single-phase fluorite structure formed at the relatively low calcination temperature of 500 degrees C. The XRD patterns of the samples revealed that the crystallite size of the samples increased as calcination temperatures increased. The sintering behavior and ionic conductivity of pellets prepared from gadolinia doped ceria (GDC) powders, which were calcined at 500 degrees C, were also investigated. The relative densities of the pellets, which were sintered at temperatures above 1300 degrees C, were higher than 95%. The results of the impedance spectroscopy revealed that the GDC-20 sample that was sintered at 1400 degrees C exhibited an ionic conductivity of 3.25 x 10(-2) S cm(-1) at 800 degrees C in air. This result clearly indicates that GDC powder with adequate ionic conductivity can be prepared through the polyol process at low temperatures. (C) 2013 Elsevier Ltd and Techna Group S.r.l. All rights reserved.