Cation transport behavior in SOFC cathode materials of La0.8Sr0.2CoO3 and La0.8Sr0.2FeO3 with perovskite structure
Haruo Kishimoto, a, , Natsuko Sakaia, Teruhisa Horitaa, Katsuhiko Yamajia, Manuel E. Britoa and Harumi Yokokawaa
aNational Institute of Advanced Industrial Science and Technology (AIST) AIST Tsukuba Central No.5, Higashi 1-1-1, Tsukuba 305-8565, Japan Received 26 December 2006; revised 29 June 2007; accepted 7 July 2007. Available online 13 August 2007.
Cation transport behavior, diffusion and interface reaction were investigated for La0.8Sr0.2CoO3 (LSC) and La0.8Sr0.2FeO3 (LSF) perovskite cathodes for solid oxide fuel cells (SOFCs). Diffusion couples between two perovskite pellets were annealed around SOFC operating temperatures such as 1071 K, 1175 K, 1279 K and 1379 K. Mass transfer of the iron component from the LSF into the LSC was clearly observed by energy dispersed X-ray analysis (EDX) and secondary ion mass spectrometry (SIMS). At the interface, the precipitation of CoFe2O4 spinel phase was observed on the LSF side. On the LSC side interface, Sr-rich thin layer was observed; iron component diffused through the CoFe2O4 and the Sr-rich thin layer at high temperature. The grain boundary diffusion of iron was faster than bulk diffusion. The interdiffusion coefficients in bulk are determined by fitting curves of SIMS profiles as follows:
Corresponding author. Fuel Cell Group, Energy Technology Research Institute National Institute of Advanced Industrial Science and Technology (AIST) AIST Tsukuba Central No.5, Higashi 1-1-1, Tsukuba 305-8565, Japan. Tel.: +81 29 861 4542; fax: +81 29 861 4540.