Reactions between strontium-substituted lanthanum manganite and yttria-stabilized zirconia: II, diffusion couples

Formation of secondary phases and diffusion of cations in diffusion couples of yttria-stabilized zirconia and lanthanum manganite substituted with 0 t o 60 mol% strontium have been studied by scanning electron microscopy and e nergy dispersive X-ray spectroscopy. Only the primary phases were observed after 120 h at 1200 degrees C, while formation of secondary phases was iden tified already after 1 h heat treatment at 1350 degrees C, The phase compos ition of the reaction layer altered from La2Zr2O7 to SrZrO3 at increasing S r content in LaxSr1-xMnO3. The thickness of the reaction layer was increasi ng with heat treatment time. In diffusion couples of La0.4Sr0.6MnO3 formati on of manganese oxide was observed in the perovskite layer after 1 h heat t reatment at 1350 degrees C, while isolated grains of SrZrO3 relatively deep inside the zirconia were observed after longer heat treatment time. Diffus ion of Mn into zirconia was observed preferenced along grain boundaries in the early stage of the interface reaction.