文摘
The redox characteristics of oxygen storage materials BaLnMn2O5+δ, with Ln = La, Nd, Gd, and Y, were investigated employing the reductive water dissolution by the deoxygenated δ = 0 form. The Ln = La, Nd, and Gd compounds were found to show a capability to produce hydrogen gas through the water dissolution at 500 °C, whereas the Ln = Y compound was unreactive to water. It was also revealed that the reactivity obviously depends upon the Ln species: the larger the ionic size of Ln3+, the higher reactivity the BaLnMn2O5.0 samples exhibit. The experimentally derived thermodynamic parameters of the BaLnMn2O5+δ series were compared to those obtained by first-principles calculations.