Li, M., Zhang, H., Cook, S.N. et al. (4 more authors) (2015) Dramatic Influence of A-Site Nonstoichiometry on the Electrical Conductivity and Conduction Mechanisms in the Perovskite Oxide Na0.5Bi0.5TiO3. Chemistry of Materials, 27 (2). pp. 629-634. ISSN 0897-4756
Abstract
Recently, there has been considerable interest in the perovskite phase Na0.5Bi0.5TiO3 (NBT) as a promising lead-free piezoelectric material. Here we report low levels of Na nonstoichiometry (±2 atom % on the A-site) in the nominal starting composition of NBT ceramics can lead to dramatic changes in the magnitude of the bulk (grain) conductivity (σb) and the conduction mechanism(s). Nominal starting compositions with Na excess exhibit high levels of oxide-ion conduction with σb ∼ 2.2 mS cm–1 at 600 °C and an activation energy (Ea) < 1 eV whereas those with Na deficiency are dielectrics based on intrinsic electronic conduction across the band gap with σb ∼ 1.6 μS cm–1 at 600 °C and Ea ∼ 1.7 eV. Drying of reagents, especially Na2CO3, changes the starting stoichiometry slightly due to a small amount of adsorbed moisture in the raw materials but influences significantly the electrical properties. This demonstrates the bulk electrical properties of NBT to be highly sensitive to low levels of A-site nonstoichiometry and reveals how to fine-tune the nominal starting composition of NBT ceramics to suppress leakage conductivity for piezoelectric and high temperature capacitor applications.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2014 American Chemical Society. This is an author produced version of a paper subsequently published in Chemistry of Materials. Uploaded in accordance with the publisher's self-archiving policy. |
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) |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 24 Feb 2016 11:00 |
Last Modified: | 22 Mar 2016 06:47 |
Published Version: | http://dx.doi.org/10.1021/cm504475k |
Status: | Published |
Publisher: | American Chemical Society |
Refereed: | Yes |
Identification Number: | 10.1021/cm504475k |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:95564 |