Stability and compatibility of lanthanum silicates electrolyte with standard cathode materials

Abstract Lanthanum silicate (LSO) electrolytes doped with different valence cations are successfully synthesized by solid state reaction. Crystal structure, electrical properties, stability and compatibility with cathode materials are characterized. The measured total conductivities of LSO electrolytes doped with In 3+ , Nb 5+ and W 6+ are relatively high compared with that of undoped La 10 Si 6 O 27 , which is attributed to more carriers including either excessive oxygen vacancies generated when doping with In 3+ or more interstitial oxide-ion O (5) generated when doping with Nb 5+ and W 6+ . The thermal expansion coefficients of La 10 Si 5.9 A 0.1 O 27± δ (A = In 3+ , Si 4+ , Nb 5+ , W 6+ ) electrolytes vary from 8.48 to 8.83 × 10 –6 K –1 at 1073 K. The doped LSO electrolytes match well with (La 0.75 Sr 0.25 ) 0.95 MnO 3± δ cathode at temperatures below 1573 K, which is highly stable, to some extent, in various atmospheres of CO 2 or H 2 O vapour.