Li, L. orcid.org/0000-0002-9565-9830, Roncal-Herrero, T., Harrington, J. et al. (4 more authors) (2021) Anomalous grain boundary conduction in BiScO3-BaTiO3 high temperature dielectrics. Acta Materialia, 216. 117136. ISSN 1359-6454
Abstract
A combination of X-ray diffraction, analytical-electron microscopy, differential scanning calorimetry, impedance spectroscopy and electromotive force measurements (for oxide-ion transport number measurements, tion) are used to report on the influence of a small amount of a continuous Bi2O3-rich phase along the grain boundaries in sample composition x = 0.4 (BS0.4BT) of the high temperature dielectric solid solution series, x(BiScO3)-(1-x)(BaTiO3). Its presence produces a dramatic change in conductivity of ~ two orders of magnitude and a switch in tion over the range ~ 600 - 800 °C that is not observed for other ceramics with lower BiScO3 content. Below ~ 700 °C the grain boundaries in BS0.4BT act as electrically blocking layers and dominate the impedance of the ceramics. In contrast, at > 800 °C the grain boundaries become highly conductive due to a polymorphic phase transition to, and melting of δ-Bi2O3 which results in the current percolating along the grain boundaries and therefore avoiding the grains. The value of tion increases from ~ 0.13 at ~ 600 °C to near unity at ~ 800 °C for BS0.4BT, consistent with oxide ion conduction due to the presence of liquid Bi2O3 at grain boundary regions. This behaviour was reproduced by adding a small excess of 3 wt% Bi2O3 into x = 0.3 (BS0.3BT) samples to induce a Bi2O3-rich grain boundary phase, not otherwise present in this composition.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2021 Acta Materialia Inc. This is an author produced version of a paper subsequently published in Acta Materialia. Uploaded in accordance with the publisher's self-archiving policy. Article available under the terms of the CC-BY-NC-ND licence (https://creativecommons.org/licenses/by-nc-nd/4.0/). |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Engineering (Sheffield) > Department of Materials Science and Engineering (Sheffield) |
Funding Information: | Funder Grant number Engineering and Physical Science Research Council EP/P015565/1 |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 12 Aug 2021 10:25 |
Last Modified: | 06 Jul 2022 00:13 |
Status: | Published |
Publisher: | Elsevier BV |
Refereed: | Yes |
Identification Number: | 10.1016/j.actamat.2021.117136 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:177054 |
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