Oxygen mobility and surface reactivity of Sm-doped Pr nickelates as promising materials for solid oxide cell air electrodes

First-order Ruddlesden–Popper phases A2BO4+δ are promising air electrode materials for solid oxide fuel cell and electrolyzer due to their high oxygen mobility. Doping the A site with smaller lanthanide cations offers a potential route to further enhance this property, yet experimental results remain controversial. In this work, for the first time, Pr2−xSmxNiO4+δ (x = 0.2 and 0.4) are synthesized using both conventional furnace sintering and radiation-thermal sintering by electron beam, and their oxygen transport properties are systematically evaluated. Single-phase materials are obtained at 1150 °C, and scanning electron microscopy reveals porous ceramics — a key microstructural feature for electrodes. Oxygen mobility and surface reactivity are assessed by temperature-programmed isotope exchange with C18O2 and 18O2. The oxygen heteroexchange rate shows minimal dependence on Sm content, but is strongly influenced by sintering technique and temperature, reflecting surface-sensitive effects. The oxygen tracer diffusion coefficients of Sm-doped Pr nickelates are lower compared to those for undoped Pr nickelate; however, they remain sufficiently high for practical application. Radiation-thermally sintered samples exhibit the highest oxygen tracer diffusion coefficients (up to 2.5·10−7 cm2/s at 700 °C) amongst Sm-doped Pr nickelates, attributed to electron-beam-induced structural disordering, strain, and defect generation. These findings establish Sm-doped praseodymium nickelates as promising electrode materials and highlight radiation-thermal sintering as an effective route for fabricating porous ceramics with enhanced transport properties.