Evaluation of applicability of Nd- and Sm-substituted Y1-xRxMnO3+δ in temperature swing absorption for energy-related technologies

Abstract

An attempt is undertaken to chemically modify YMnO3+δ by the partial substitution of Y with larger Nd and Sm, aiming to boost the oxygen storage performance in the temperature swing process. Single-phase (P63cm) Y0.95Nd0.05MnO3+δ and Y0.95Sm0.05MnO3+δ compounds are obtained in a sol-gel auto-combustion process followed by the annealing at 1000 °C in Ar. Both materials show improved oxygen storage capacity, however, doping with Nd3+ enables the effective operation in air – capacity reached 1453 μmol-O g−1, which is over 86% of the capacity in O2. As documented for the Nd-containing sample, oxygen absorption is accompanied by oxidation of Mn3+ to Mn4+, and no changes in the valence of neodymium occur. The reversible oxygen intake and release occur at exceptionally low temperatures for Y0.95Nd0.05MnO3+δ, as low as in the 201–240 °C range. This enables utilization of the recovery of low- and medium-temperature waste heat. In addition, the paper presents the impact of the preparation route of the material on the oxygen storage-related performance. It is shown that lowering of the annealing temperature allows to further increase the rate of O2 absorption, making the material a promising candidate for practical application, however, it results also in the presence of the secondary phases.