Electrode redox properties of Ba1−xLaxFeO3−δ as cobalt free cathode materials for intermediate-temperature SOFCs

A DFT+U study of A-site and B-site substitution in BaFeO3−δ

“…20,21 Although a recent study demonstrated the successful fabrication of the cubic phase for low temperature (200 o C) upon oxidation in ozone, this structure also exhibited a high oxygen site occupancy. 22 The stabilization of the cubic structure and the high oxygen deficiency has also been obtained by substituting Sr, Ce, La, Y, Ca 16,21,[23][24][25][26][27] into the A-stability, and cell performances comparable to cobalt-based cathodes. 16,21 Although the strategy of stabilizing BFO by substitution is commonly employed, significant ambiguity exists as to the electronic and geometric effects of each site doping.…”

“…In addition, other studies have identified different structural and crystal characteristics for the same materials, for example, an oxygen deficiency of δ=0.27 27 (for iodometry at 930 o C) and δ=0.38 25 (for iodometry at room temperature) for La Ba at 10% substitution level. Most often the substitution location (A site or B site) is determined from the initial stoichiometry of the material constituents and analysis of XRD data.…”

Enhanced oxygen reduction activity on surface-decorated perovskite La 0.6 Ni 0.4 FeO 3 cathode for solid oxide fuel cells

“…[47]. BLF is recently reported as a promising cobalt-free cathode and the electric conductivity BLF was 17 S cm À1 at 800 C [48,49]. Because of the absence of cobalt element in BLF, the electrocatalyst activity of BLF was less than that of BSCF whose electric conductivity achieved to 37 S cm À1 at 800 C. Because of the high conductivity and high oxygen vacancy concentration, a composition near x = 1.0 for Ce 1Àx Pr x O 2Àd (i.e., PrO 2Àd ) is favorable for the active layer material of an SOFC cathode [50].…”

Pulsed laser deposition of La 0.6 Ca 0.4 Fe 0.8 Ni 0.2 O 3−δ thin films on SrTiO 3 : Preparation, characterization and electrical properties

“…Compared with cobalt-based cathode materials such as Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3 − δ and Ln 1 −x A x CoO 3 − δ (Ln = lanthanides) typically like La 1 − x Sr x CoO 3 despite having excellent electrochemical performance, suffers from problems such as a very high thermal expansion coefficient and high reactivity with the SOFC electrolyte material (yttria stabilized zirconia (YSZ)), which makes it necessary to apply additional barrier layers or to use alternative solid electrolytes in the cell. On the other hand, chemical instability and high temperature volatility of perovskite iron-based cathodes such as Ln 1 − x A x FeO 3 − δ phases (for example, La 0.3 Sr 0.7 FeO 3 − δ , and La 0.6 Sr 0.4 Fe 0.9 Ni 0.1 O 3 − δ ), show close thermal expansion coefficient with electrolyte, good long-term stability and high Cr-resistance sacrificing partly electrochemical activity [8,9]. In this materials, when the Fe fraction is higher than 0.5 the materials exhibit a high electronic conductivity.…”