Computational study of the substitution of early actinides and Ce into zirconolite
Computational study of the substitution of early actinides and Ce into zirconolite
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DOI：
10.1016/j.jnucmat.2020.152525
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发表时间：
2021
影响因子：
3.1
通讯作者：
J. Tanti;N. Kaltsoyannis
中科院分区：
文献类型：
--
作者：
J. Tanti;N. Kaltsoyannis
本文用混合密度泛函理论结合周期静电嵌入团簇方法，分析了四价早锕系元素（Th-Am）和Ce在锆英石陶瓷核废料CaZrTi 2 O 7中的置换。用Fe 3+和Al 3+平衡电荷，模拟了Zr 4+和Ca 2+两个离子位上的取代。在集群中的离子的中心区域的平均位移表示氧化还原行为，然后通过自旋密度数据的分析确认。发现这些离子的取代能与取代基和取代离子的离子半径比之间存在很强的相关性。Ce 4+和Pu 4+取代到晶格中的氧化还原行为和取代能相似。分子M（OH）n（M= Ce，Th-Am，n= 3-5）的自旋密度数据表明，较晚的锕系元素更倾向于+3氧化态，这与锆英石簇中的结果一致。
Substitutions of tetravalent early actinides (Th–Am) and Ce into the ceramic nuclear waste form zirconolite, CaZrTi 2 O 7, have been analysed using hybrid Density Functional Theory in conjunction with the Periodic Electrostatic Embedded Cluster Method. Substitutions on to both Zr 4+ and Ca 2+ sites were modelled, with Fe 3+ and Al 3+ used for charge balancing. The mean displacements of a central region of ions in the cluster indicated redox behaviour which was then confirmed through analysis of spin density data. Strong correlations were found between the substitution energies of these ions and the ratio of the ionic radii of substituents and substituted ions. Similar redox behaviour and substitution energies were seen for substitutions of Ce 4+ and Pu 4+ into the lattice. Spin density data of molecular M (OH) n (M= Ce, Th-Am, n= 3–5) showed a preference for the+ 3 oxidation state for later actinides-as seen in the zirconolite clusters.