Zhang Yingjie, Aughterson Robert D, Zhang Zhaoming, Wei Tao, Lu Kimbal, Čejka Jiří, Karatchevtseva Inna
Australian Nuclear Science and Technology Organisation (ANSTO) , Locked Bag 2001 , Kirrawee DC , New South Wales 2232 , Australia.
Department of Mineralogy and Petrology , National Museum , Cirkusová 1740 , 19300 Prague 9 , Czech Republic.
Inorg Chem. 2019 Aug 19;58(16):10812-10821. doi: 10.1021/acs.inorgchem.9b01102. Epub 2019 Aug 2.
We have synthesized two uranyl oxide hydrate (UOH) phases incorporating La(III) or Nd(III) ions under hydrothermal conditions. Investigations with scanning electron microscopy and transmission electron microscopy (TEM) revealed thin-plate morphologies with a U-to-Ln atomic ratio of 2:1 (Ln = La or Nd), while single-crystal X-ray diffraction and TEM electron diffraction studies confirmed that both UOH phases crystallized in the trigonal 31 space group with uranyl oxide layered structures incorporating La(III)/Nd(III) ions as interlayer species. Vibrational spectroscopic studies revealed typical vibrational modes for U ions, with the derived U═O bond lengths being comparable to the values reported on other UOH phases. Bond-valence-sum calculations suggest hexavalent uranium in the uranyl form, which was confirmed by the results of diffuse-reflectance and X-ray absorption near-edge structure spectroscopies. This work reports the first single-crystal structural investigation of UOH phases with Ln ions, which has significant implications in the weathering products of uraninite mineral in nature as well as the alteration products of spent nuclear fuels during interim storage and safe disposal over geological timespans.
我们在水热条件下合成了两种掺入La(III)或Nd(III)离子的氢氧化铀酰（UOH）相。扫描电子显微镜和透射电子显微镜（TEM）研究表明，其呈现出薄板形态，U与Ln的原子比为2:1（Ln = La或Nd），而单晶X射线衍射和TEM电子衍射研究证实，两种UOH相均在三角31空间群中结晶，其氧化铀层状结构中含有La(III)/Nd(III)离子作为层间物种。振动光谱研究揭示了U离子的典型振动模式，推导得出的U═O键长与其他UOH相报道的值相当。键价和计算表明铀酰形式的铀为六价，这通过漫反射和X射线吸收近边结构光谱的结果得到了证实。这项工作报道了首次对含Ln离子的UOH相进行单晶结构研究，这对天然沥青铀矿矿物的风化产物以及地质时间跨度内乏核燃料在中间储存和安全处置期间的蚀变产物具有重要意义。
