Effect of B-site substitution on the stability of La0.2Sr0.8Fe0.8B0.2O3-δ, B = Al, Ga, Cr, Ti, Ta, Nb

Single phase, cubic perovskites of composition La0.2Sr0.8Fe0.8B0.2O3 - delta, B = Al, Ga, Cr, Ti, Ta and Nb, were prepared by spray pyrolysis from aqueous precursor solutions. The effect of B-site substitution on the stability in a H-2 containing atmosphere was investigated using temperature programmed reduction (TPR). High temperature X-ray diffraction (HT-XRD) was performed under conditions similar to those in the TPR experiments. La0.2Sr0.8FeO3 - delta forms a brownmillerite-type anion-deficient ordered perovskite upon reduction at T approximate to 500. B-site substitution suppresses oxygen vacancy ordering, maintaining a perovskite structure under the above reducing conditions up to T approximate to 700 degrees C. Trends in the kinetics of decomposition of B-site substituted La0.2Sr0.8FeO3 - delta are discussed. (c) 2012 Elsevier B.V. All rights reserved.