Mechanism of Reaction between Lanthanum Manganite and Yttria‐Stabilized Zirconia

Abstract

The reaction of La 1‐ x Ca x MnO 3 ( x = 0, 0.1, 0.2) with ZrO 2 ‐8 mol% Y 2 O 3 (YSZ) has been investigated at temperatures ranging from 1300° to 1425°C in air. Substitution of Ca for La in LaMnO 3 depresses the reactivity with YSZ. A layer of La 2 Zr 2 O 7 is formed at the La 1‐ x Ca x MnO 3 /YSZ interface after an induction period, and its formation is accelerated when the La 1‐ x Ca x MnO 3 phase is porous. The reaction proceeds by unidirectional diffusion of La, Mn, and/or Ca ions, mainly Mn ions, into YSZ. The diffusion coefficients of La and Mn ions in YSZ, which are estimated using a LaMnO 3 /single‐crystal YSZ couple, are much lower than that of oxygen ion. From the experimental data, a reaction mechanism is proposed.