Elucidation of the Transport Properties of Calcium‐Doped High Entropy Rare Earth Aluminates for Solid Oxide Fuel Cell Applications

Solid oxide fuel cells (SOFCs) are paving the way to clean energy conversion,relying on efficient oxygen-ion conductors with high ionic conductivitycoupled with a negligible electronic contribution. Doped rare earth aluminatesare promising candidates for SOFC electrolytes due to their high ionicconductivity. However, they often suffer from p-type electronic conductivity atoperating temperatures above 500°C under oxidizing conditions caused bythe incorporation of oxygen into the lattice. High entropy materials are a newclass of materials conceptualized to be stable at higher temperatures due totheir high configurational entropy. Introducing this concept to rare earthaluminates can be a promising approach to stabilize the lattice by shifting thestoichiometric point of the oxides to higher oxygen activities, and thereby,reducing the p-type electronic conductivity in the relevant oxygen partialpressure range. In this study, the high entropy oxide (Gd,La,Nd,Pr,Sm)AlO3issynthesized and doped with Ca. The Ca-doped (Gd,La,Nd,Pr,Sm)AlO3compounds exhibit a higher ionic conductivity than most of thecorresponding Ca-doped rare earth aluminates accompanied by a reduction ofthe p-type electronic conductivity contribution typically observed underoxidizing conditions. ... mehrIn light of these findings, this study introduces highentropy aluminates as a promising candidate for SOFC electrolytes.