0000000000147292
AUTHOR
Maximilian F. Hoedl
Impact of point defects on the elastic properties of BaZrO3: Comprehensive insight from experiments and ab initio calculations
Abstract Acceptor doped BaZrO3 is the prototype of proton conducting perovskites which are of strong interest as electrolytes for intermediate temperature fuel cells. Elastic properties of both dry and hydrated Y-doped BaZrO3 (1.5–17 mol% Y) were determined using ultrasound time of flight (TOF) measurements, and complemented by ab initio calculations which allow for an analysis of the different contributions. The experimental and theoretical findings are consistent and reveal a strong decrease of the Young's, shear and bulk moduli upon increasing dopant concentration. This decrease is attributed to a combined effect of (i) macroscopic lattice chemical expansion mainly caused by differing io…
X-ray Spectroscopy of (Ba,Sr,La)(Fe,Zn,Y)O3-δIdentifies Structural and Electronic Features Favoring Proton Uptake
Mixed protonic–electronic conducting oxides are key functional materials for protonic ceramic fuel cells. Here, (Ba,Sr,La)(Fe,Zn,Y)O3−δ perovskites are comprehensively investigated by X-ray spectroscopy (in oxidized and reduced states). Extended X-ray absorption fine structure shows that Zn,Y doping strongly increases the tendency for Fe–O–Fe buckling. X-ray absorption near-edge spectroscopy at the Fe K-edge and X-ray Raman scattering at the O K edge demonstrate that both iron and oxygen states are involved when the samples are oxidized, and for the Zn,Y doped materials, the hole transfer from iron to oxygen is less pronounced. This can be correlated with the observation that these material…
Interdependence of Oxygenation and Hydration in Mixed-Conducting (Ba,Sr)FeO3-δPerovskites Studied by Density Functional Theory
Financial support by the German–Israeli Foundation for Scientific Research and Development (grant I-1342-302.5/2016) and the Latvian Council of Science (grant lzp-2018/1-0147 (D.G., E.A.K.)) is gratefully acknowledged. The authors further thank Guntars Zvejnieks for help with CRYSTAL code calculations.
Proton, Hydroxide Ion, and Oxide Ion Affinities of Closed-Shell Oxides: Importance for the Hydration Reaction and Correlation to Electronic Structure
Phenomenologically, the enthalpy of the dissociative water incorporation (hydration) of oxides is often found to be more favorable for more basic oxides. In the present work, we investigate proton,...