Transport Properties

Defect Interactions in Sr3La(Fe,Al)3O10−δ by Computer Simulations and Mössbauer Spectroscopy

“…Moreover, if even the lattice is oxygen-stoichiometric, the presence of octahedrally coordinated Al 3+ and Fe 4+ in the adjacent sites causes modest but significant repulsion. The corresponding Δ E values, ∼0.1 eV, are close to the typical level of small-polaron migration energies in perovskite-like ferrites . The repulsive interactions originate, first of all, from local lattice distortions near Al 3+ .…”

“…At the same time, Coulombic repulsion between Fe 4+ and oxygen vacancies excludes their location in nearest-neighboring sites (Δ E = +1.16 eV, Table ), unless the relatively stable ternary clusters Fe 4+ −V O −Fe 2+ are formed owing to trivalent iron disproportionation, 2Fe 3+ ⇔ Fe 4+ + Fe 2+ . The latter reaction should be taken into account for the analysis of high-temperature redox equilibria in ferrites − but can be neglected under oxidizing conditions when the electronic subsystem is dominated by holes generated due to oxygen intercalation. The same statement is true for Fe 2+ states which could be, in fact, ignored in the range of conditions studied in this work, as their concentration at δ < 1 is negligibly small.…”

Composite Nafion Membranes with CaTiO3−δ Additive for Possible Applications in Electrochemical Devices

“…Titanium-based oxides are very attractive materials, thanks to their good features in terms of cost, stability, and high natural abundance, triggering the R&D toward the improvement of their chemical–physical properties by the study of their chemistry and surface geometry, making them useful to several research fields [9]. In particular, oxides with a perovskite structure are materials that have found the potential for a wide range of applications, such as sensors, optical devices, and solid-oxide-fuel-cells electrodes and electrolytes [10].…”

Versatile Application of Redox Processes for REBaCoMnO5+δ (RE: La, Pr, Nd, Sm, Gd, and Y) Oxides

“…However, it also results from the lowered oxygen bonding strength at the RE-related structural positions. , At elevated temperatures (600–800 °C, working range of IT-SOFCs), high concentration of the oxygen vacancies is observed, forming fast ion-conducting planes, which are being the source of the enhanced ionic component of the conductivity. Simultaneously, the considered REBaCo 2 O 5+δ compounds exhibit particularly high, p -type electronic conductivity, which originates from the double-exchange (Zener) mechanism. − Effectiveness of this process can be disturbed (even to a high extend) by appearance of the oxygen vacancies, which break B–O–B double exchange. Considering structural features of REBaB 2 O 5+δ , nature of the electrical conduction can be considered as anisotropic in terms of both, the electronic and ionic components.…”