This is the first paper reporting that lanthanum tungstate, earlier believed to be La₆WO₁₂, is in fact La_28−xW_{4 +}xO_54+δ , where tungsten dissolves in lanthanum sites to form a stable solid-state electrolyte, exhibiting proton conduction by hydration at intermediate temperatures.

Redox stable SrFe_0.75Mo_0.25O_3-δ and SrFe_0.5Mn_0.25Mo_0.25O_3-δ electrode materials were studied in terms of their physicochemical properties and electrochemical performance in symmetrical SOFCs, with focus on their tolerance toward carbon deposition and sulfur poisoning. Both materials possess cubic, B-site cation-disordered Pm-3m structure in air up to high temperatures. SrFe_0.5Mn_0.25Mo_0.25O_3-δ was found to transform to a B-site cation-ordered structure after reduction in dry 5 vol% H₂/Ar at 1100°C, while no structural changes were observed for SrFe_0.75Mo_0.25O_3-δ. Weight change upon annealing up to 850°C in air and in dry 5 vol% H₂/Ar indicated an increase in oxygen deficiency on the order of δ = 0.2. Seebeck coefficient and conductivity dependence on the oxygen partial pressure pO₂ showed that both oxides exhibit p-type conductivity in air and n-type conductivity under reducing conditions. Carbon deposition was found to depend on temperature, gas composition (CO or CH₄), and presence of Ce_0.8Gd_0.2O_1.9 electrolyte in the composite-type electrode. Stable fuel cell performance, without carbon deposition, was obtained for SrFe_0.75Mo_0.25O_3-δ-based SOFC in 10 vol% of CO in CO₂. Also, SOFC operation with CH₄ as fuel was achieved without coking at temperatures ≤ 700°C. However, both oxides suffer from sulfur poisoning-related effects in atmosphere with 800 ppm H₂S.

The defect chemistry of foreign transition metals in perovskite oxides was investigated by first-principles calculations in combination with experiments with focus on Ni and Zn in Y-doped BaZrO₃.

Enhanced oxide ion diffusion by 3 to 5 orders of magnitude along grain boundary core in Sr-doped LaMnO₃.