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Synthesis of zirconolite-2M ceramics for immobilisation of neptunium
- Publication Year :
- 2021
- Publisher :
- Elsevier BV, 2021.
-
Abstract
- Praseodymium-doped zirconolite ceramics targeting nominal composition Ca1-xPrxZrTi2-5x/3Al5x/3O7 (x ≤ 0.20, Δx = 0.05) were fabricated by a mixed oxide solid state reaction, at 1350 °C in air for 20 h. Praseodymium (Pr) was employed as a surrogate for neptunium (Np), with Al3+ co-accommodated to provide charge balance. High-resolution transmission electron microscopy and electron diffraction analyses confirmed that zirconolite crystallised as the 2 M monoclinic polytype throughout the phase evolution, with no evidence of transformation to other polytype structures. Phase assemblage and microstructural data were consistent with zirconolite occupying a high fraction of the phase assemblage (>ca. 93 wt %), alongside a minor secondary perovskite phase at all levels of targeted Pr incorporation. Despite this, it was demonstrated near theoretical density formed through a solid-state fabrication route, and we therefore propose that, through analogy with the corresponding Pr solid solution, zirconolite may be a suitable candidate for the immobilisation of Np-bearing wastes.
Details
- Language :
- English
- ISSN :
- 02728842
- Database :
- OpenAIRE
- Accession number :
- edsair.core.ac.uk....e4fce52979e4a7c2bf2ab30b4855d0c7