Oxide Ion and Proton Conductivity in Highly Oxygen-Deficient Cubic Perovskite SrSc 0.3 Zn 0.2 Ga 0.5 O 2.4

Chloe A Fuller (1) , Quentin Berrod (2, 3) , Bernhard Frick (4) , Mark Johnson (4) , Maxim Avdeev (5) , John Evans (1) , Ivana Radosavljevic Evans (1)

1 Department of Chemistry [Durham, UK]
2 STEP - Synthèse, Structure et Propriétés de Matériaux Fonctionnels
3 DIESE - Département Interfaces pour l'énergie, la Santé et l'Environnement
4 ILL - Institut Laue-Langevin
5 Bragg Institute

A series of Zn-substituted compounds, Sr2Sc1-xZnxGaO5-0.5x, based on the brownmillerite-type oxide ion conductor Sr2ScGaO5 have been synthesized and a single-phase region identified at 0.4 ≤ x < 0.6. The structure and dynamics of Sr2Sc0.6Zn0.4GaO4.8 were investigated by X-ray and neutron diffraction, neutron total scattering and pair distribution function (PDF) analysis, impedance spectroscopy and neutron spectroscopy. The material was found to be a highly-disordered cubic perovskite with a remarkable level of oxygen deficiency across a large temperature range. These structural properties lead to an increase of oxide ion conductivity of about two orders of magnitude relative to the parent Sr2ScGaO5. The presence of proton conductivity and some water uptake was suggested by the impedance data and corroborated by thermogravimetric analysis (TGA), solid state nuclear magnetic resonance (NMR), variable temperature X-ray diffraction and neutron spectroscopy. Both proton and oxide ion conductivity produced a measurable quasi-elastic neutron scattering (QENS) signal and the onset of each dynamic process could be observed by monitoring the tempera-ture dependence of the elastic and inelastic scattering intensities measured in fixed window scans. Neutron total scatter-ing and PDF studies revealed a local structure that is markedly different from the perovskite average structure, and we propose it contains a rare one-coordinate or terminal oxygen site.

Mots clés: Oxide ion conductor; neutron spectroscopy; local structure

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Chloe A Fuller, Quentin Berrod, Bernhard Frick, Mark Johnson, Maxim Avdeev, et al.. Oxide Ion and Proton Conductivity in Highly Oxygen-Deficient Cubic Perovskite SrSc 0.3 Zn 0.2 Ga 0.5 O 2.4. Chemistry of Materials, 2020, ⟨10.1021/acs.chemmater.0c01378⟩. ⟨hal-02556986⟩