Baran, JD, Kepaptsoglou, D, Molinari, M et al. (5 more authors) (2016) Role of Structure and Defect Chemistry in High-Performance Thermoelectric Bismuth Strontium Cobalt Oxides. Chemistry of Materials, 28 (20). pp. 7470-7478. ISSN 0897-4756
Abstract
[Bi₀.₈₇SrO₂]₂[CoO₂]₁.₈₂ (BSCO) is one of the best p-type thermoelectric oxides but its structural and electronic properties are still poorly understood. BSCO is a misfit-layered compound consisting of an incommensurate stacking of hexagonal CoO₂ and double rock-salt BiSrO₂ layers. Here we combine experimental and computational approaches to investigate its crystallographic and electronic structure as well as thermoelectric transport properties. Considering different approximations for the subsystems stacking, we present a structural model that agrees well with both bulk and atomic-scale experimental data. This model, which suggests a level of Bi deficiency in the rock-salt layers, is then used to discuss the material’s electronic, magnetic, and transport properties. We show that Bi deficiency leads to a band gap opening and increases p-type electronic conductivity due to the formation of Co⁴+ species that serve as itinerant holes within the predominantly Co³+ framework of the CoO₂ layer. We validate these predictions using electron energy loss spectroscopy in the scanning transmission electron microscope. The relationship between the hole-doping mechanism and the changes of the local structure (in particular the level of Bi deficiency) is evaluated. The reliability of the simulations is supported by the calculated temperature dependence of the Seebeck coefficient, in good agreement with experimental measurements.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | (c) 2016, American Chemical Society. This document is the Accepted Manuscript version of a Published Work that appeared in final form in Chemistry of Materials, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acs.chemmater.6b03200 |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Chemical & Process Engineering (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 25 May 2018 09:52 |
Last Modified: | 25 May 2018 09:52 |
Status: | Published |
Publisher: | American Chemical Society |
Identification Number: | 10.1021/acs.chemmater.6b03200 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:131223 |