Short-Range Structure and Phonon Assignment of the Brownmillerite-Type Oxide Ba$_{2}$In$_{2}$O$_{5}$ and its Hydrated Proton-Conducting Form BaInO$_{3}$H

Johan Bielecki; Stewart F. Parker; Dharshani Ekanayake; Seikh M. H. Rahman; Lars Börjesson; Maths Karlsson

paper

Short-Range Structure and Phonon Assignment of the Brownmillerite-Type Oxide Ba $_{2}$ In $_{2}$ O $_{5}$ and its Hydrated Proton-Conducting Form BaInO $_{3}$ H

arXiv:1404.1034

Abstract

The vibrational spectra and short-range structure of the brownmillerite-type oxide Ba $_{2}$ In $_{2}$ O $_{5}$ and its hydrated form BaInO $_{3}$ H, are investigated by means of Raman, infrared, and inelastic neutron scattering spectroscopies together with density functional theory calculations. For Ba $_{2}$ In $_{2}$ O $_{5}$ , which may be described as an oxygen deficient perovskite structure with alternating layers of InO $_{6}$ octahedra and InO $_{4}$ tetrahedra, the results affirm a short-range structure of $I c mm$ symmetry, which is characterized by random orientation of successive layers of InO $_{4}$ tetrahedra. For the hydrated, proton conducting, form, BaInO $_{3}$ H, the results suggest that the short-range structure is more complicated than the $P 4/ mbm$ symmetry that has been proposed previously on the basis of neutron diffraction, but rather suggest a proton configuration close to the lowest energy structure predicted by Martinez et al. [J.-R. Martinez, C. E. Moen, S. Stoelen, N. L. Allan, J. of Solid State Chem. 180, 3388, (2007)]. An intense Raman active vibration at 150 cm $^{- 1}$ is identified as a unique fingerprint of this proton configuration.

Short-Range Structure and Phonon Assignment of the Brownmillerite-Type Oxide Ba2​In2​O5​ and its Hydrated Proton-Conducting Form BaInO3​H

Abstract

Short-Range Structure and Phonon Assignment of the Brownmillerite-Type Oxide Ba $_{2}$ In $_{2}$ O $_{5}$ and its Hydrated Proton-Conducting Form BaInO $_{3}$ H