Syntheses, Crystal Structures, and Spectroscopic Studies of Uranyl Oxide Hydrate Phases with La(III)/Nd(III) Ions

Abstract

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 P31m 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.

Incorporation of iodine into uranium oxyhydroxide phases

“…A plethora of UOH phases, both as minerals and synthetic compounds, have been previously examined particularly by Burns and co-workers, among others. 7,23,25,39,[53][54][55] A consistent trend among the UOH phases is their adoption of layered 2D structures which possess hydroxyl groups and distinctive voids in their layers (see Fig. 1b and 2).…”

“…This consistent topology affords structural modifications of UOH phases containing alkali, alkaline earth, transition and also lanthanide cations in the interlayer space. 7,8,25,53,54 Paragenetically it is understood that ternary UOH phases such as metaschoepite form prior to alkali or alkaline earth metal containing quaternary phases such as compreignacite or becquerelite. 2,3,56 The inclusion of cations in the interlayer space of UOH phases generally involves them coordinating via the hydroxyl positions, where the void positions are vacant comparatively.…”

“…22 It has been previously suggested that UOH phases, considering their structural chemistry and proximity of formation to SNF, can intercalate fission species, particularly cationic, during unexpected release. 7,8 However, there are at present no studies that have examined the potential retention of anionic fission species into UOH phases for instance radiolytic iodine, despite the renewed focus these materials have recently received [23][24][25][26] coupled with the broader reinvigorated interest in actinide and actinide-iodine chemical science. [27][28][29][30][31][32][33][34][35][36][37] In the present investigation, we describe the synthesis and characterisation of a novel UOH structure which successfully intercalates IO (0.45 g, 1 mmol), KIO 3 (0.07 g, 0.3 mmol) and RbIO 3 (0.08 g, 0.3 mmol) were mixed and dissolved in 2 ml deionised water and dilute HNO 3 was added to reduce the pH to 5 which was checked via pH paper.…”

Hidden and apparent twins in uranyl-oxide minerals agrinierite and rameauite: a demonstration of metric and reticular merohedry

“…Casas et al, 1997;Finch & Murakami, 1999;Kubatko et al 2006;Klingensmith et al, 2007;Gorman-Lewis et al, 2008) due to the general importance of UOHs in nuclear waste disposal and the environmental chemistry of uranium. Nevertheless, the results of recent scientific efforts have proven even greater complexity and variability of the entire group (Kirkegaard et al, 2019;Lu, Zhang, Wei et al, 2020;Lu, Zhang, Aughterson & Zheng, 2020;Olds et al, 2017Olds et al, , 2018Pla ´s ˇil, 2017Pla ´s ˇil, , 2018bPla ´s ˇil et al, , 2020Zhang et al, 2016Zhang et al, , 2018Zhang et al, , 2019.…”

A hexanuclear Nd (III) complex derived from a Schiff base with significant antitumor and antifungal activity

“…Lanthanide-based complexes are currently being investigated extensively for a variety of functionalities and applications, such as optical probes, medicine, microelectronics, and others. [1][2][3][4][5][6][7][8][9][10][11] However, only limited kinds of metal complexes can be used as the anticancer drug in clinic among which platinum (II) and ruthenium (III) complexes are the most popular studied. Cancer patients undergoing chemotherapy usually possess a chance of 20% suffering Candida infection, and most antitumor drugs show no antifungal activities.…”