Oxygen Mobility of Samarium Doped Neodymium Nickelates Sintered by E-Beams

Abstract

Ruddlesden–Popper phases are known materials for electrochemical devices such as solid oxide fuel cells/electrolyzers, oxygen separation membranes. Doping A-site with lanthanides with less radii can allow increasing the oxygen mobility, however, this problem is still not studied well. This work aims at studying phase composition and transport properties of Sm doped Nd nickelates sintered by radiation-thermal technique using e-beams. Nd_{2 – x}Sm_xNiO_{4 + δ} (x = 0.2, 0.4) were synthesized by modified Pechini technique and sintered by e-beams at 1150–1250°C. The materials obtained were characterized by X-ray diffraction, X‑ray photoelectron spectroscopy and temperature-programmed isotope exchange of oxygen with C¹⁸O₂ in a flow reactor. The surface oxygen is present in two forms differing in binding energy. According to the temperature-programmed isotope exchange data, the samples exhibit nonuniformity in the oxygen mobility, and slow diffusion channel is present for the sample with x = 0.4. Such an oxygen diffusion features are probably related to the effect of doping and radiation-thermal sintering on the structure with formation of admixed phases, hampering the cooperative migration due to emergence of local defects and variation of the surface and grain boundary composition.