Exploring the physical properties of Eu₂SrCo_1.5Mn_0.5O₇, a new n = 2 member of the Ruddlesden–Popper series (Eu,Sr)_n+1(Co,Mn)_nO_3n+1

Abstract

A new oxide of the Ruddlesden-Popper series has been isolated and structurally characterized in the Eu-Sr-Co-Mn-O system. X-ray diffraction and electron microscopy show that polycrystalline Eu 2 SrCo 1.5 Mn 0.5 O 7 constitutes the n=2 member of a homologous series, the essential feature of which is the existence of two connected Co/Mn octahedral layers, separated by Eu atoms. Electrochemical study shows that, the area-specific resistance of this compound is 0.15Ω cm 2 at 700 ºC in air, a performance which is comparable to that of the best state-of-the-art materials used as cathode in intermediate temperature solid oxide fuel cells. Below 150 K the title material presents two different magnetic phenomena. The first one corresponds to the formation of ferromagnetic nanoclusters (T C ∼121 K) within an ordered Co 2+ /Mn 4+ atomic configuration, whereas at lower temperature (∼21 K) a spin glass state occurs. Figure 3. (a) HAADF image of along Eu 2 SrCo 1.5 Mn 0.5 O 7 [0 1 0]. A schematic model for cationic position has been inserted. (b) Corresponding ABF image where cationic atoms are in red and oxygen are in blue. Interstitial oxygen ions are indicated by blue arrows. a along [110] pseudocubic axis in a given two-layer perovskite block and along [-110] direction in adjacent blocks. Physical Properties Magnetic behaviour.The magnetic behaviour of oxides is related to metal oxidation states, charge localization and ordering phenomena, which are also related with transport properties. Thus, magnetic measurements may help to understand the electrical properties of a given material.

Hydride-Reduced Eu2SrFe2O6: A T-to-T′ Conversion Enabling Fe2+ in Square-Planar Coordination

“…The size mismatch resulting from A-site ordering between the rock-salt (RS) block (occupied by Eu 3+ ) and the perovskite block (occupied by Sr 2+ ) can be released by coherent octahedral tilting. The octahedral tilting results in a highly distorted structure, with an enlarged in-plane cell of √2 a p × √2 b p compared with the nondistorted primitive ( a p × b p ) cell. An increased symmetry is suggested from the laboratory XRD pattern after hydride reduction (Figure a), with all reflections indexed within the I 4/ mmm space group based on the Sr 3 Ti 2 O 7 RP aristotype.…”

Structural and microstructural characterization and properties of new phases in the Nd–Sr–Co–(Fe/Mn)–O system as air-electrodes in SOFCs

“…Even more, the discovery of high oxide-ionic conductivity in A n+1 B n O 3n+1 oxides has stimulated the search for new R-P materials with Mixed Ionic-Electronic Conductors (MIEC) for electrodes in Intermediate Temperature Solid Oxide Fuel Cells (IT-SOFCs). [8][9][10][11][12][13][14][15] The interest of the R-P oxides as electrodes in IT-SOFCs has been mainly focused on materials with K 2 NiF 4 -like structure, which is the n=1 member of the homologous series, where one-octahedron-thick perovskite layers alternate with single AO rock salt sheets along the packing axis, [10][11][12][13] though there are some articles reporting the properties of n = 2 and 3 members.…”

An Effective Strategy to Enhance the Electrocatalytic Activity of Ruddlesden−Popper Oxides Sr3Fe2O7−δ Electrodes for Solid Oxide Fuel Cells

“…The Rp values of SFO, SFC10 and SFC20 cathode materials are 0.39, 0.11 and 0.18 Ω cm 2 at 700 °C, respectively. Noticeably, the SFC10 cathode exhibits the lowest Rp value among the SFCx cathodes at 700 °C, which is much smaller than the reported R-P type cathodes [38][39][40][41][42][43] (Figure 6b), suggesting the great promise of SFC10 as a high electrochemical activity cathode electrocatalyst. Additionally, the activation energy (Ea) of the cathodes was obtained from the Arrhenius plot, as presented in Figure 6c.…”