Preparation and characterization of Ln0.8Sr0.2Fe0.8Co0.2O3-x (Ln = La, Pr, Nd, Sm, Eu, Gd)

In the present study the oxides Ln(0.8)Sr(0.2)Fe(0.8)Co(0.2)O(3-x) (Ln = La, Pr, Nd, Sm, Eu, Gd) were prepared and characterized to study the influence of the host rare earth cation on their properties and their potential application as intermediate temperature solid oxide fuel cell cathodes with higher ionic conductivity, lower linear thermal expansion coefficient and better chemical compatibility with the electrolyte. The oxides were prepared by the amorphous citrate synthesis. From X-ray powder diffraction measurements it was deduced that all oxides were single-phased with the sensitivity of the method. However, irregularities during thermal expansion measurements indicated that some structural changes might occur during heating. Only after examination of the powders in a scanning electron microscope, the presence of a second phase (cobalt oxide) in most compositions became evident. (C) 2001 Elsevier Science Ltd.