Reactions between strontium-substituted lanthanum manganite and yttria-stabilized zirconia: I, Powder samples

Abstract

Sintered submicrometer powder mixtures of strontium-substituted lanthanum manganite and yttria-stabilized zirconia have been studied in order to investigate the chemical stability of these materials as respectively electrode and electrolyte in solid oxide fuel cells. Formation of secondary phases was observed after 1 h heat treatment at 1350 °C and more than 13 h at 1200 °C. La2Zr2O7 was formed in mixtures with LaMnO3 at 1350 °C, while SrZrO3 was formed in mixtures containing La0.6Sr0.4MnO3 or La0.4Sr0.6MnO3. Only minor amounts of secondary phases were observed in mixtures with La0.7Sr0.3MnO3. Chemical analysis revealed considerable interdiffusion between the primary phases as well as A-site deficiency of LaMnO3 and La0.7Sr0.3MnO3 when exposed to cubic zirconia. The oxidative/reductive nature of the chemical reaction between strontium-substituted lanthanum manganite and yttria-stabilized zirconia is discussed in relation to the Sr content in LSM. The lattice parameter of cubic zirconia was observed to be quite sensitive to the interdiffusion and is an excellent tool for investigating reactions on heterophase interfaces involving stabilized zirconia.