Precipitation of dopants on acceptor-doped LaMnO_3±δ revealed by defect chemistry from first principles

Perovskite oxides degrade at elevated temperatures while precipitating dopant-rich particles on the surface. A knowledge-based improvement of surface stability requires a fundamental and quantitative understanding dopant precipitation mechanism these materials. We propose that is consequence variation solubility between calcination operating conditions in solid oxide fuel cells (SOFCs) electrolyzer (SOECs). To study precipitation, we use 20% (D = Ca, Sr, Ba)-doped LaMnO3+δ (LDM20) as model system. employ defect taking input from density functional theory calculations. The considers equilibration LDM20 with reservoir consisting (DO), peroxide (DO2), O2 gas phase. equilibrated non-stoichiometry A-site B-site function temperature, T, oxygen partial pressure, p(O2), reveals three regimes for LDM20: deficient (oxidizing conditions), rich (atmospheric near-stoichiometric (reducing conditions). Assuming an initial A/B non-stoichiometry, compute boundaries p–T phase diagram. Our predicts both under reducing (DO) highly oxidizing (DO2). found anodic, SOEC to be promoted by large size, cathodic, SOFC excess. main driving forces are uptake condensed release assisted vacancies conditions. Possible strategies mitigating electrolytic cell discussed.