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
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Date
2017-02-23
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Publisher
Wiley
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. © 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim
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Keywords
Transmission electron microscopy, Neutron diffraction, Ionic conductivity, X-ray diffraction, Electrolytes, Spectroscopy
Citation
Tate, M. L., Blom, D. A., Avdeev, M., Brand, H. E. A., 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), 1605625. doi:10.1002/adfm.201605625