Electrical Properties of Fe-doped Perovskite-like BaNb _0.75-xFe_xNa_0.25O_3-δ (0.05 < x < 0.5)

In this paper, we report the electrical properties of Fe-doped perovskite-like compounds with a nominal chemical formula of BaNb _0.75-xNa_0.25Fe_xO_3-δ (0.05 < x < 0.5) (BNF). Various solid-state structural and electrical characterization techniques, including powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), alternating current (AC) impedance spectroscopy and direct current (DC) methods were used for characterization. PXRD patterns for BNF members show the formation of perovskite-like structure. The total electrical conductivity values were determined under ambient air and wet air in the temperature up to 700 °C. The Fe concentration was strongly correlated to the conductivity response, with the x = 0.5 member exhibiting the highest conductivity in air. A relationship between the humidity content and conductivity in air was also observed in low Fe concentration BNF members (x = 0.5, 0.15), suggesting the presence of potential proton conduction; while the conductivity of high Fe content samples (x ≥ 0.3) showed little dependence on the humidity. The chemical stability of BNF samples was investigated in boiling H₂O and in flowing 100% CO₂ at elevated temperatures and the results demonstrated that all members were structurally stable under both conditions, except the x = 0.5 member which decomposed into BaCO₃ in the presence of CO₂ at 800 °C.