Structural and electrochemical characterization of La2LxSrxNiTiO6-d

Abstract

Materials of the series La2-xSrxNiTiO6-d (0 < x < 0.5) have been characterized by both structural and electrochemical methods in order to assess their possible use as electrodes for SOFCs. Neutron and X-ray powder diffraction experiments have shown that they are stable under both oxidizing and reducing conditions while chemically compatible with YSZ at SOFC operating temperatures. Moreover, the thermal expansion has been determined to be isotropic with alpha = 10.0(3) x 10-6 K-1. This value is similar to that found for other perovskite materials used in SOFCs. However, polarization resistances reveal modest values of electrochemical response under oxygen (1.5 Ohms cm2 at 900 C) and are quite poor in 5%H2/N2 mixtures (15 Ohms cm2) at the same temperature. Nevertheless, microstructure has not been optimized fully enough to discard the material as a potential SOFC cathode.