Oxygen transport properties of La2Ni1-xCuxO4+δ mixed conducting oxides

Materials formulated La2N1-xCuxO4+delta (0 less than or equal to X less than or equal to 1) have been prepared and characterized using various techniques: a particular attention has been paid to their mixed conduction properties in view of application as SOFC cathode. These oxides show a good thermal stability in terms of oxygen over-stoichiometry and thermal expansion coefficient (TEC approximate to 13 x 10(-6) K-1). In addition, they exhibit high electrical conductivity (approximate to100 wS(.)cm(-1)) as well as high values of oxygen diffusion and surface exchange coefficients (D* and k) which have been determined using secondary ion mass spectroscopy (SIMS) of the O-18 isotope. Highly dense ceramics have been prepared for these measurements, which has required a specific study of the densification of these materials. They exhibit D* and k coefficients one order of magnitude higher than those of the best perovskite materials. The pure nickelate seems to show the most promising properties for the oxygen reduction electrocatalysis. (C) 2003 Editions scientifiques et medicales Elsevier SAS. All rights reserved.