Crystal structure and oxygen storage properties of BaLnMn2O5+δ (Ln: Pr, Nd, Sm, Gd, Dy, Er and Y) oxides

Redox behavior of the SOFC electrode candidate NdBaMn2O5+δ investigated by high-temperature in situ neutron diffraction: first characterisation in real time of an LnBaMn2O5.5 intermediate phase

“…The diffraction profile of NdBaMn2O5+, displayed in Fig. S2, gave lattice parameters a = 5.61512(2) Å and c = 7.73895(4) Å, consistent with the values reported for the compound prepared by solid-state reaction 16,18 . The structure, illustrated in Figure 2, is similar to that of YBaCuFeO5 19 and consists of two distinct square pyramidal Consequently, the P4/nmm space group is considered.…”

“…Our single step process consists of annealing the precursors under 5% H2/N2 at 800 °C and 750 °C for two periods of 12 h with an intermediate regrind and preparation of new pellets between these two annealing periods. Our synthesis method also differs from the two-step process used to obtain PrBaMn2O5+δ 10 and from the synthesis under argon atmosphere at T ~ 1350 °C 15 or under 1% H2/Ar atmosphere at 1100 °C 16 previously used to prepare the determined by iodometric titration for the oxidized sample was 6.002(2), close to expected value of 6.0.…”

“…The A-site ordered NdBaMn2O5+δ (δ ~ 0) phase has previously been prepared by sol-gel or solid state reaction methods 12,15,16 . This double perovskite is difficult to prepare in a pure form and controlled oxygen atmosphere and temperature are required.…”

“…phase was fitted to an orthorhombic 2ap × 2ap × 4ap Icma model on the basis of the secondary phase detected during the reduction of NdBaMn2O6 which was assumed to be of the Icma-type 16 . The Icma structure observed for half-oxygenated layered manganites with small A-site cations, such as YBaMn2O5.5 36 and TbBaMn2O5.5 37 consists of alternating pairs of octahedra and pyramids stacked along the c direction.…”

A determination of the oxygen non-stoichiometry of the oxygen storage material YBaMn2O5+

“…The oxygen uptake/release kinetics of YBaMn 2 O 5 þ δ have been studied by Motohashi et al, who also determined the pO 2 dependence of the inter-conversion of YBaMn 2 O 5.5 and YBaMn 2 O $ 6 by thermogravimetric analysis in the pO 2 range 10-10 5 Pa (10 À 4 to 1 atm) and also the range of composition of 'O 6 ' [22][23][24]. We note also that systems with Y partially or completely substituted with other rare-earth elements (La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, and Er) have been investigated [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44].…”