New Apatite-Type Oxide Ion Conductor, Bi2La8[(GeO4)6]O3: Structure, Properties, and Direct Imaging of Low-Level Interstitial Oxygen Atoms Using Aberration-Corrected Scanning Transmission Electron Microscopy

Tate, Matthew L.; Blom, Douglas A.; Avdeev, Maxim; Brand, Helen E.A.; McIntyre, Garry J.; Vogt, Thomas; Evans, Ivana Radosavljevic

Abstract

The new solid electrolyte Bi2La8[(GeO4)6]O3 is prepared and characterized by variable-temperature synchrotron X-ray and neutron diffraction, aberration-corrected scanning transmission electron microscopy, and physical property measurements (impedance spectroscopy and second harmonic generation). The material is a triclinic variant of the apatite structure type and owes its ionic conductivity to the presence of oxide ion interstitials. A combination of annular bright-field scanning transmission electron microscopy experiments and frozen-phonon multislice simulations enables direct imaging of the crucial interstitial oxygen atoms present at a level of 8 out of 1030 electrons per formula unit of the material, and crystallographically disordered, in the unit cell. Scanning transmission electron microscopy also leads to a direct observation of the local departures from the centrosymmetric average structure determined by diffraction. As no second harmonic generation signal is observed, these displacements are non-cooperative on the longer length scales probed by optical methods.

Citation

Tate, M. L., Blom, D. A., Avdeev, M., Brand, H. E., McIntyre, G. J., Vogt, T., & Evans, I. R. (2017). New Apatite-Type Oxide Ion Conductor, Bi2La8[(GeO4)6]O3: Structure, Properties, and Direct Imaging of Low-Level Interstitial Oxygen Atoms Using Aberration-Corrected Scanning Transmission Electron Microscopy. Advanced Functional Materials, 27(8), Article 1605625. https://doi.org/10.1002/adfm.201605625

• Journal Article Type: Article
• Acceptance Date: Dec 12, 2016
• Online Publication Date: Jan 18, 2017
• Publication Date: Feb 23, 2017
• Deposit Date: Jan 24, 2017
• Publicly Available Date: Jan 18, 2018
• Journal: Advanced Functional Materials
• Print ISSN: 1616-301X
• Electronic ISSN: 1616-3028
• Publisher: Wiley
• Peer Reviewed: Peer Reviewed
• Volume: 27
• Issue: 8
• Article Number: 1605625
• DOI: https://doi.org/10.1002/adfm.201605625
• Public URL: https://durham-repository.worktribe.com/output/1365686