Ablott Timothy A, Lu Kimbal T, Zhang Yingjie
Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee, New South Wales 2232, Australia.
ACS Omega. 2024 Aug 23;9(36):38284-38294. doi: 10.1021/acsomega.4c06188. eCollection 2024 Sep 10.
The synthesis of two zinc-bearing uranium oxide hydrate (UOH) materials has been achieved, and their crystal structures, obtained via single-crystal X-ray diffraction using synchrotron radiation, and additional structural and spectroscopic properties are reported herein. Although both structures incorporate Zn cations, the two differ significantly. The compound Zn(OH)(HO)[(UO)UO(HO)] (), forming a framework-type structure in the 1̅ space group, was composed of β-UO layers pillared by uranyl polyhedra, with the Zn cations incorporated within the framework channels. In contrast, the compound CsZn(HO)[(UO)O(OH)]·3HO () crystallized in the 2 space group with a schoepite-like uranyl oxide hydroxide layered topology and both Zn and Cs cations making up the interlayer species. The apparent driving force for the differences in the structures was the change from KOH to CsOH during synthesis, with the smaller K ions excluded in lieu of a higher proportion of Zn (U/Zn ratio of 5.5:1) in , whereas in , the larger Cs ions were preferentially incorporated at the expense of fewer Zn cations (U/Cs/Zn ratio of 8:2:1). Highlighted in this work is the effect of the chemical species and, in particular, their ionic radius on UOH formation, further improving the understanding of UO alteration in the setting of deep geological repositories.
已经成功合成了两种含锌的氢氧化铀酰（UOH）材料，本文报道了它们通过同步辐射单晶X射线衍射获得的晶体结构以及其他结构和光谱性质。尽管两种结构都包含锌阳离子，但二者存在显著差异。化合物Zn(OH)(HO)[(UO)UO(HO)]（）在1̅空间群中形成骨架型结构，由铀酰多面体支撑的β-UO层组成，锌阳离子包含在骨架通道内。相比之下，化合物CsZn(HO)[(UO)O(OH)]·3HO（）在2空间群中结晶，具有水磷铀矿型氢氧化铀酰氧化物层状拓扑结构，锌和铯阳离子构成层间物种。结构差异的明显驱动力是合成过程中从氢氧化钾到氢氧化铯的变化，较小的钾离子被排除在外，取而代之的是中较高比例的锌（U/Zn比为5.5:1），而在中，较大的铯离子优先被纳入，锌阳离子较少（U/Cs/Zn比为8:2:1）。这项工作突出了化学物种的影响，特别是它们的离子半径对UOH形成的影响，进一步增进了对深部地质处置库环境中UO蚀变的理解。
