Long-range charge transfer and oxygen vacancy interactions in strontium ferrite

Abstract

Long-range charge transfer leads to oxygen vacancy interactions in strontium ferrites.

Interaction of SrO-terminated SrTiO3 surface with oxygen, carbon dioxide, and water

“…The value of U for Ti was estimated to be 8.0 eV by reproducing the optical band gap of SrTiO 3 , 3.2 eV, and comparing with data from the literature. [32][33] Vibrational frequency calculations require (1) = -In equation 1 A denotes the preexponential factor, Ea is the activation barrier obtained from the NEB calculations, R is the gas constant, and T is the reaction temperature. The preexponential factor contains information for the collision probability between the participating species.…”

Challenges in Sr2FeMoO6−δ Thin Film Deposition

“…In cubic SrFeO 3− δ ′ , the oxygen vacancy formation energy exhibits a constant low value (≈0.4 eV) for δ < 0.05; increases to ≈0.5 eV for 0.05 < δ < 0.1; and further increases quickly with concentration when δ > ≈0.1 . This increase is attributed to the local charge redistribution after V O formation and to overlapping local lattice transformations.…”

“…[5] In cubic SrFeO 3Àδ 0 , the oxygen vacancy formation energy exhibits a constant low value (%0.4 eV) for δ < 0.05; increases to %0.5 eV for 0.05 < δ < 0.1; and further increases quickly with concentration when δ > %0.1. [86] This increase is attributed to the local charge redistribution after V O formation and to overlapping local lattice transformations. By the same reason, the dependence of SFMO oxygen diffusion activation energy on oxygen nonstoichiometry [87] provides evidence of vacancy interactions over distances at least up to four unit cells.…”

Oxygen vacancy formation in the SrTiO3 Σ5 [001] twist grain boundary from first‐principles

“…All the atomic positions were relaxed until all components of the residual forces were smaller than 0.02 eV/Ǻ, and the convergence threshold for self‐consistent‐field iteration was set to 10 −5 eV. It is noted that DFT studies of transition metal oxides often require U corrections to properly describe the strongly correlated d ‐orbitals . We have carried out a series of test calculations to determine whether including a correction of 5.8 eV on Ti 3 d orbitals would impact our conclusions.…”

“…It is noted that DFT studies of transition metal oxides often require U corrections to properly describe the strongly correlated d-orbitals. [61][62][63] We have carried out a series of test calculations to determine whether including a U correction of 5.8 eV on Ti 3d orbitals 64 would impact our conclusions. We found that the trend of formation energy values is completely unchanged, in spite of slight changes in the absolute values, indicating that U corrections have little effect on studying the formation energy trend of oxygen vacancies in the SrTiO 3 twist grain boundary.…”