Conductivity and redox stability of perovskite oxide SrFe1-xTixO3-δ (x≤ 0.3)

A solid solution with the cubic perovskite structure was observed for SrFe1-xTixO3-δ (x = 0–0.3), with an increase in the lattice parameters noted upon increasing dopant concentration. Material stability in air was observed for all compounds, with a decrease in conductivity noted upon increasing dopant concentration attributed to a reduction in charge carrier concentration. A reduction in weight proportional to the titanium content was observed upon exposure to 5% H2/Ar, although reduction at 700 °C was observed to elicit a structural transitions and the formation of a secondary phase for samples SrFeO3-δ and SrFe0.9Ti0.1O3-δ respectively. Conductivity measurements at 600 °C demonstrated a larger decrease in the conductivity with increasing dopant concentration, while all investigated oxides are stable after reducing in 5%H2/Ar at 600 °C. It was found that the conductivity of SrFe0.8Ti0.2O3-δ and SrFe0.7Ti0.3O3-δ in 5%H2/Ar is insufficient to be used as anode for SOFCs. In the investigated compositions, SrFe0.9Ti0.1O3-δ exhibits desired conductivity and redox stability, reduced thermal expansion coefficient compared to SrFeO3-δ, which is a promising redox stable anode for IT-SOFCs.