δ-Bi 2 O 3 has long been touted as a potential material for use in solid oxide fuel cells (SOFC) due to its intrinsically high ionic conductivity. However, its limited operational temperature has led to stabilising the phase from >725 °C to room temperature either by doping, albeit with a compromise in conductivity, or by growing the phase confined within superlattice thin films. Superlattice architectures are challenging to implement in functional μSOFC devices owing to their ionic conducting channels being in the plane of the film. Vertically aligned nanocomposites (VANs) have the potential to overcome these limitations, as their nanocolumnar structures are perpendicular to the plane of the film, hence connecting the electrodes at top and bottom. Here, we demonstrate for the first time the growth of epitaxially stabilised δ-Bi 2 O 3 in VAN films, stabilised independently of substrate strain. The phase is doped with Dy and is formed in a VAN film which incorporates DyMnO 3 as a vertically epitaxially stabilising matrix phase. Our VAN films exhibit very high ionic conductivity, reaching 10 −3 S cm −1 at 500 °C. This work opens up the possibility to incorporate thin film δ-Bi 2 O 3 based VANs into functional μSOFC devices, either as cathodes (by pairing δ-Bi 2 O 3 with a catalytically active electronic conductor) and/or electrolytes (by incorporating δ-Bi 2 O 3 with an insulator).
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A pathway to desired functionalities in vertically aligned nanocomposites and related architectures
Abstract Epitaxial vertically aligned nanocomposites (VANs) and their related architectures have shown many intriguing features that are not available from conventional two-dimensional planar multilayers and heterostructures. The ability to control constituent, interface, microstructure, strain, and defects based on VANs has enabled the multiple degrees of freedom to manipulate the optical, magnetic, electrochemical, electronic, ionic, and superconducting properties for specific applications. This field has rapidly expanded from the interest in oxide:oxide to oxide:metal, metal:nitride and nitride:nitride systems. To achieve unparalleled properties of the materials, three-dimensional super-nanocomposites based on a hybrid of VAN and multilayer architectures have been recently explored as well. The challenges and opportunities of VAN films are also discussed in this article.
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- NSF-PAR ID:
- 10230953
- Date Published:
- Journal Name:
- MRS Bulletin
- Volume:
- 46
- Issue:
- 2
- ISSN:
- 0883-7694
- Page Range / eLocation ID:
- 115 to 122
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1557/s43577-021-00032-4
