Synthesis and characterization of La0.6Sr0.4Fe0.8Cu0.2O3− oxide as cathode for Intermediate Temperature Solid Oxide Fuel Cells

Abstract

Nanocrystalline La 0.6 Sr 0.4 Fe 0.8 Cu 0.2 O 3 (LSFCu) material was synthetized by combustion method using EDTA as fuel/chelating agent and NH 4 NO 3 as combustion promoter. Structural characterization using thermodiffraction data allowed to determine a reversible phase transition at 425 1C from a low temperature R-3c phase to a high temperature Pm-3m phase and to calculate the thermal expansion coefficient (TEC) of both phases. Important characteristics for cathode application as electronic conductivity and chemical compatibility with Ce 0.9 Gd 0.1 O 2 (CGO) electrolyte were evaluated. LSFCu presented a p-type conductor behavior with maximum conductivity of 135 S cm 1 at 275 1C and showed a good stability with CGO electrolyte at high temperatures. This work confirmed that as prepared LSFCu has excellent microstructural characteristics and an electrical conductivity between 100 and 60 S cm 1 in the 500-700 1C range which is sufficiently high to work as intermediate temperature Solid Oxide Fuel Cells (IT-SOFCs) cathode. However a change in the thermal expansion coefficient consistent with a small oxygen loss process may affect the electrode-electrolyte interface during fabrication and operation of a SOFC.