Chemical Compatibility between Strontium‐Doped Lanthanum Manganite and Yttria‐Stabilized Zirconia

Abstract

Equimolar powder mixtures and multilayer pellets of single‐phase Sr‐doped lanthanum manganite perovskite materials Lay‐xSrxMnO3 with La content y = 1 and 0.95 and Sr content 0 ≤ x ≤ 0.5 were annealed in air with 8 mol% Y2O3‐ZrO2 at 1470 K, up to 400 h and at 1670 K. up to 200 h. X‐ray diffraction and electron probe microanalysis confirmed the formation of La2Zr2O7 or SrZrO3 depending on the composition of the perovskites. No reaction products could be detected for La0.95‐xSr xMnO3 with 0.2 ≤ x ≤ 0.4 after annealing for 400 h at 1470 K, and for the perovskite La0.65Sr0.3MnO3 even after annealing for 200 h at 1670 K. The results demonstrate the improved chemical compatibility of La‐deficient perovskites against reaction with zirconia and can provide a basis for the selection of a sufficiently chemically stable material for the air electrode of solid oxide fuel cells.

Materiais cerâmicos para células a combustível

“…Em termos de estabilidade do catodo em relação aos outros componentes da célula, o LSM pode ser considerado estável quando em contato com um eletrólito de zircônia-ítria na temperatura de trabalho de uma célula a combustível; no entanto, para temperaturas maiores que 1250-1350 °C, conforme mencionado anteriormente, é formada uma camada intermediária da fase pirocloro La 2 Zr 2 O 7 e/ou SrZrO 3 [45]. Em geral, nos LSM a substituição de pequenas quantidades de Sr nos sítios A aumenta a estabilidade com relação aos eletrólitos de zircônia-ítria (menor tendência de formação de La 2 Zr 2 O 7 ).…”

Ceramic Materials for Advanced Solid Oxide Fuel Cells

“…These perovskites are electronic p-type conductors for which the electrical properties are determined by the La/Sr ratio. The formation of La 2 Zr 2 O 7 and SrO is inhibited by incorporating an excess of Mn (1±10 %) in the composition and keeping the sintering temperature below 1300 C. [26] These two compounds impair cathode performance due to solid state reactions.…”

Characterization of yttria-stabilized zirconia films deposited by dip-coating on La0.7Sr0.3MnO3 substrate: Influence of synthesis parameters

“…The formation of these secondary phases is more pronounced for the samples prepared with lower viscosity. It is well known that LSM can react with YSZ at high temperatures to form insulating phases of La 2 Zr 2 O 7 (LZ) and SrZrO 3 (SZ) [3,16,17]. Both phases weaken the electrical contact of cathode/electrolyte because the conductivity of these zirconates is at least 2-3 orders of magnitude lower than that of YSZ electrolyte [18].…”