Abstract:As
mixed ionic–electronic conductors (MIECs), ABO3 perovskite
oxides and derivative compounds are candidates for applications
such as solid oxide fuel and electrolysis cells. Understanding the
atomic configuration and electronic structure of MIECs is important
because they form the basis of ionic and electronic conductivities;
but it is challenging because the materials tend to be non-dilute
systems with substantial partial occupancies of the perovskite sublattices.
In this work, we present a computational mod… Show more
“…13 Such disagreement between the model and the measurement results was explained by oxygen vacancy ordering, typical of highly nonstoichiometric SrFeO 3– δ (ref. 13) as well as similar oxides such as SrFe 1– x Ti x O 3– δ , 141,142 impacting ε chem values. This conclusion is qualitatively supported by the DFT simulation results, showing increasing oxygen vacancy polaron size with increasing δ in Sr 1– x La x FeO 3– δ due to the vacancy ordering.…”
Section: Various Models and Approaches To Understand The Chemical Exp...mentioning
Strong coupling between the chemical composition and crystal lattice dimensions resulting in the contraction or expansion of a material upon change of its chemical composition is known as chemical expansion...
“…13 Such disagreement between the model and the measurement results was explained by oxygen vacancy ordering, typical of highly nonstoichiometric SrFeO 3– δ (ref. 13) as well as similar oxides such as SrFe 1– x Ti x O 3– δ , 141,142 impacting ε chem values. This conclusion is qualitatively supported by the DFT simulation results, showing increasing oxygen vacancy polaron size with increasing δ in Sr 1– x La x FeO 3– δ due to the vacancy ordering.…”
Section: Various Models and Approaches To Understand The Chemical Exp...mentioning
Strong coupling between the chemical composition and crystal lattice dimensions resulting in the contraction or expansion of a material upon change of its chemical composition is known as chemical expansion...
“…More Ni atoms were expected to exsolve from the lattice during long term reductive treatment, unless lattice stress or phase decomposition stopped the process. [ 25,27 ]…”
One way to avoid CO2 pollution is changing it into CO by solid oxide electrolyzers, in which doped SrTiO3 can be used as cathode materials. It is found that in situ exsolved Ni nanoparticles in doped SrTiO3 cathode can further improve the electrolysis performance. In this work, (La0.2Sr0.8)0.85Ti0.8Cr0.1Ni0.1O3−δ cathode with in situ exsolved Ni particles is investigated. A new model proposed explains the influence of exsolution process on crystal structure. Based on thermogravimetric analysis, it is estimated that about 13.6% to 37.4% Ni atoms exsolve out of original cathode. With the new cathode containing Ni nanoparticles, the yield of CO from electrolysis is improved at about 50% and the current efficiency is increased at about 10%.
“…Crystalline STF35 is a strongly ptype system under oxidizing conditions, and the electronic conduction occurs through the directional O-2p and Fe-3d orbitals, 14 which are partially covalent. 25,52 Oxidation produces four holes per oxygen molecule incorporated, which contributes to the increase in hole concentration, according to eqn (2):…”
Crystallization of a perovskite mixed conductor is coupled to oxidation, which drives defect chemistry, ion coordination, polyhedra alignment, hierarchical microstructure, and property evolution – including a boost to electrical conductivity.
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