A Potential Wasteform for Cs Immobilization: Synthesis, Structure Determination, and Aqueous Durability of Cs2TiNb6O18

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• 作者：Tzu-Yu Chen ; Ewan R. Maddrell ; Neil C. Hyatt ; Joseph A. Hriljac
• 刊名：Inorganic Chemistry
• 出版年：2016
• 出版时间：December 19, 2016
• 年：2016
• 卷：55
• 期：24
• 页码：12686-12695
• 全文大小：488K
• ISSN：1520-510X

文摘

Cs₂TiNb₆O₁₈ is a potential ceramic wasteform for the long-term immobilization of radioactive cesium. Cs₂TiNb₆O₁₈ was synthesized using the aqueous precursor method and a solid-state reaction, and its crystal structure was determined from the Rietveld refinement of synchrotron X-ray and neutron powder diffraction data. The structure is a pyrochlore analogue, space group P3̅m1 with Cs in 9-fold coordination. The calculated bond valence sum from analysis of neutron diffraction data of 0.84 and high coordination number suggest that Cs has a strong bonding environment. The chemical aqueous durability was investigated using the MCC-1 and PCT-B standard test methods. The measured Cs leach rates of 3.8 × 10^–3 and 2.1 × 10^–3 g m^–2 day^–1 obtained via the MCC-1 and PCT-B methods, respectively, demonstrate good promise of a safe long-term immobilization material comparable to, if not better than, hollandite—the material in the multiphase titanate ceramics (Synroc) targeted for cesium sequestration.