Synthesis and preliminary study of La4BaCu5O13 + δ and La6.4Sr1.6Cu8O20 ± δ ordered perovskites as SOFC/PCFC electrode materials

Abstract

La4BaCu5O13+δ (LBCu) and La6.4Sr1.6Cu8O20±δ (LSCu) oxygen deficient perovskites, synthesized by a Pechini-type gel combustion method, have been investigated as potential cathode materials for IT-SOFC applications. The thermal stability and chemical compatibility with SOFC/PCFC electrolyte materials are examined using X-ray diffraction technique. For both compounds, no structural change is detected in air until 900°C. The evolution of cell parameters with temperature shows thermal expansion coefficients (TEC) of 17.3×10−6K−1 and 12.1×10−6K−1 for LBCu and LSCu, respectively. For LBCu, the formation of oxygen vacancies is evidenced between 700 and 900°C in air. Chemical reactivity tests with several SOFC electrolyte materials reveal a high reactivity of both cuprates with YSZ, GDC and, to a lesser extent, with LSGM. On the other hand, and contrary to what occurs for LSCu, LBCu presents an excellent chemical compatibility with doped barium cerate and zirconate, opening further perspectives for this material as possible SOFC or PCFC cathode. LBCu material presents a quite high electrical conductivity with metallic-type behavior.