Mechanochemical synthesis and physicochemical properties of La1-xBaxFeO3-delta (0 <= x <= 1) perovskites

La1-xBaxFeO3-delta (X = 0-1) perovskites were prepared by the mechanical activation of mixtures of binary oxides in a centrifugal planetary ball mill for 3 min followed by calcination at 1100 degrees C for 4 h, and their phase composition was determined by X-ray diffraction. All samples up to x = 0.8 are single-phase oxides with a perovskite structure. The x = 1 sample is a mixture of perovskite- and brownmillerite-type phases. An orthorhombic-to-cubic morphotropic transition is observed at x = 0.3. The catalytic activity of the perovskite samples in CO oxidation, chosen as a model reaction, depends nonmonotonically on the barium content of the catalyst. High catalytic activities are shown by the x = 0.8 and 0.3 samples.