Dixon Wilkins, M.C.J., Gausse, C., Townsend, L.T. orcid.org/0000-0002-7991-9444 et al. (2 more authors) (2022) Characterisation of a complex CaZr0.9Ce0.1Ti2O7 glass–ceramic produced by hot isostatic pressing. Ceramics, 5 (4). pp. 1035-1050. ISSN 2571-6131
Abstract
The behaviour of Ce-containing zirconolites in hot isostatically pressed (HIPed) materials is complex, characterised by redox interactions between the metallic HIP canister that result in reduction of Ce4+ to Ce3+. In this work, a glass–ceramic of composition 70 wt.% CaZr0.9Ce0.1Ti2O7 ceramic in 30 wt.% Na2Al2Si6O16 glass was produced by HIP (approx. 170 cm3 canister) to examine the extent of the material–canister interaction. A complex material with six distinct regions was produced, with the extent of Ce reduction varying depending on the distance from the canister. Notably, the innermost bulk regions (those approximately 7 mm from the canister) contained only Ce4+, demonstrating that a production-scale HIPed glass–ceramic would indeed have a bulk region unaffected by the reducing environment induced by a ferrous HIP canister despite the flow of glass at the HIP temperature. Each of the six regions was characterised by XRD (including Rietveld method refinements), SEM/EDX and linear combination fitting of Ce L3-edge XANES spectra. Regions in the lower part of the canister were found to contain a significantly higher fraction of Ce4+ compared to the upper regions. Though zirconolite-2M was the major crystalline phase observed in all regions, the relative abundances of minor phases (including sphene, baddeleyite, rutile and perovskite) were higher in the outermost regions, which comprised a significantly reduced Ce inventory.
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Copyright, Publisher and Additional Information: | © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/). | ||||||||
Keywords: | zirconolite; hot isostatic pressing; wasteform materials; glass–ceramics | ||||||||
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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) | ||||||||
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Depositing User: | Symplectic Sheffield | ||||||||
Date Deposited: | 19 Dec 2022 12:13 | ||||||||
Last Modified: | 19 Dec 2022 12:13 | ||||||||
Status: | Published | ||||||||
Publisher: | MDPI AG | ||||||||
Refereed: | Yes | ||||||||
Identification Number: | https://doi.org/10.3390/ceramics5040074 |