In this work, we present results showing modification of the oxygen storage-related properties of perovskite-type oxides based on BaYMn 2 O 5+δ, having A-site layer-type cation order. Y 3+ is the lightest among suitable cations, which allows to obtain such the structural order, and at the same time, it provides the highest theoretical oxygen storage capacity. However, substitution of Y 3+ by Sm 3+ cations may be beneficial, and BaY 0.5 Sm 0.5 Mn 2 O 5+δ material shows enhanced reduction kinetics. Furthermore, partial substitution of Ba 2+ by Sr 2+ increases reversible oxygen storage capacity, but at the same time slows down the reduction speed. In addition, for higher concentration of strontium, it is not possible to obtain single phase materials.

Crystal structure, oxygen storage-related and preliminary anaerobic methane combustion studies were conducted for BaY 1-x Gd x Mn 2 O 5+δ (0, 0.25, 0.5, 0.75 and 1) series of oxides prepared by a solgel method. All samples were found to possess layered-type A-site cation ordering, with the unit cell volume linearly dependent on the average radius of Y 1-x Gd x for both, the reduced and the oxidized materials. The oxygen content in the temperature range of 400-600 °C indicate change on the order of 1 atomic mole, occurring when the sample's surrounding atmosphere was changed from air to 5 vol.% H 2 in Ar. The time dependence of the reduction shows activated character on temperature, with an activation energy, which seems to be related to the oxygen diffusion in the bulk of the materials. Initial data concerning methane combustion in oxygen-free conditions show promising catalytic activity of BaYMn 2 O 6 at elevated temperatures.