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 to 60 mol% strontium have been studied by scanning electron microscopy and energy dispersive X‐ray spectroscopy. Only the primary phases were observed after 120 h at 1200°C, while formation of secondary phases was identified already after 1 h heat treatment at 1350°C. The phase composition of the reaction layer altered from La 2 Zr 2 O 7 to SrZrO 3 at increasing Sr content in La x Sr 1‐ x MnO 3 . The thickness of the reaction layer was increasing with heat treatment time. In diffusion couples of La 0.4 Sr 0.6 MnO 3 formation of manganese oxide was observed in the perovskite layer after 1 h heat treatment at 1350°C, while isolated grains of SrZrO 3 relatively deep inside the zirconia were observed after longer heat treatment time. Diffusion of Mn into zirconia was observed preferenced along grain boundaries in the early stage of the interface reaction.