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Materials 2019, 12(1), 178; https://doi.org/10.3390/ma12010178

Self-Propagating Synthesis and Characterization Studies of Gd-Bearing Hf-Zirconolite Ceramic Waste Forms

1,3,* , 1
,
2
and
4,*
1
State Key Laboratory of Environment-friendly Energy Materials, Southwest University of Science and Technology, Mianyang 621010, China
2
State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070, China
3
Sichuan Civil-Military Integration Institute, Mianyang 621010, China
4
Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, China
*
Authors to whom correspondence should be addressed.
Received: 14 December 2018 / Revised: 28 December 2018 / Accepted: 30 December 2018 / Published: 7 January 2019
(This article belongs to the Special Issue Multifunctional Oxide-Based Materials: From Synthesis to Application)
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Abstract

Synroc is recognized as the second-generation waste matrice for nuclear waste disposal. Zirconolite is one of the most durable Synroc minerals. In this study, Gd and Hf were selected as the surrogates of trivalent and tetravalent actinide nuclides. Gd-bearing Hf-zirconolite (Ca1−xHf1−xGd2xTi2O7) ceramic waste forms were rapidly synthesized from a self-propagating technique using CuO as the oxidant. The results indicate that Gd can concurrently replace the Ca and Hf sites. However, Gd2O3 could not completely be incorporated into the lattice structure of zirconolite when the x value is higher than 0.8. The aqueous durability of selected Gd-Hf codoped sample (Hf-Gd-0.6) was tested, where the 42 days normalized leaching rates (LRi) of Ca, Cu, Gd and Hf are measured to be 1.57, 0.13, 4.72 × 10−7 and 1.59 × 10−8 g·m−2·d−1. View Full-Text
Keywords: self-propagating; nuclear waste; zirconolite; actinide; aqueous durability self-propagating; nuclear waste; zirconolite; actinide; aqueous durability
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Zhang, K.; Yin, D.; Xu, K.; Zhang, H. Self-Propagating Synthesis and Characterization Studies of Gd-Bearing Hf-Zirconolite Ceramic Waste Forms. Materials 2019, 12, 178.

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