A low melting-point ceramic exhibiting ultrahigh oxide-ionic conductivity and oxygen flux working at 300–500 °C

Oxide-ionic conductors are broadly used as catalytic, conducting and detecting materials under oxidizing, reducing, inert or mixed environments. However, their current issue is the demand of high work temperatures (> 600 °C) to maintain high oxide-ion conductivity (> 0.1 S cm −1 ). This work develops a Pb 5 CaBi 10 O 21 (PCBO) ceramic, and its low melting point corresponds to the low binding energy of metal-O, which facilitates the generation of lattice oxygen vacancies and the migration of oxygen ions. PCBO lowers the working temperature to 300–500 °C, and demonstrates the highest oxygen-ion transport of ever reported oxide-ionic conductors, showing 0.68 oxide-ionic transport number, 0.353 ml min −1 cm −2 oxygen flux and 0.16 S cm −1 oxide-ionic conductivity (3–5 orders of magnitudes higher than YSZ or SDC at 500 °C). The high oxide-ionic percentage and conductivity were further demonstrated by the voltage/power output of SOFCs with PCBO as electrolyte. The experimental investigation and density functional theory calculation both demonstrate the easy formation and migration of V O in PCBO, explaining its high oxygen-ion transport.