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Uranium trichloride (UCl3) has received growing interest for its use in uranium-fueled molten salt reactors and in the pyrochemical processing of used fuel. In this paper, we report for the first time the experimentally determined Raman spectra of UCl3, at both ambient condition and in situhigh temperatures up to 871 K. The frequencies of five of the Raman-active vibrational modes (vi) of UCl3exhibit a negative temperature derivative ((∂νi/∂T)P) with increasing temperature. This red-shift behavior is likely due to the elongation of U–Cl bonds. The average isobaric mode Grüneisen parameter (γiP= 0.91 ± 0.02) of UCl3was determined through use of the coefficient of thermal expansion published in Vogel et al. (2021) and the (∂νi/∂T)Pvalues determined in this study. These results are in general agreement with those calculated here by density functional theory (DFT+U). Finally, a comparison of the ambient band positions of UCl3to those of isostructural lanthanide (La–Eu) and actinide chlorides (Am–Cf) has been made.

Emerging renewable energy technologies and low-carbon transportation rely heavily on the unique optical and magnetic properties of the rare earth elements. The medium to heavy rare earth elements, neodymium to lutetium, are most sought by industry but are the least abundant in nature. Only a small proportion of known rare earth element deposits are enriched in these elements. Identifying additional sources of medium to heavy rare earth elements for resource exploration requires improved understanding of the mechanisms responsible for the formation of such highly fractionated deposits. Here we report the results of experiments demonstrating a mechanism that could lead to enrichment of medium to heavy rare earth elements in ore-forming hydrothermal systems. In our experiments, we simulated natural hydrothermal systems by heating a column containing apatite and fluorite through which we pumped a chloride-rich solution bearing rare earth elements. Analysis of our experiments shows that the fluoride mineral fluocerite can serve as a precursor phase that fractionates rare earth elements before it is subsequently converted to a thermodynamically more stable mineral. Our findings identify geological settings in which fluocerite is observed or predicted to occur as potential exploration targets for deposits enriched in medium to heavy rare earth elements.

Microorganisms moderate local chemical conditions and alter forms of metals indirectly or directly to meet their cellular, species, and consortia needs. The diversity of microorganisms and the complexity of biogeochemical systems ensures that bacterially mediated processes yield a wide range of products, which await discovery by material scientists. Few types of materials produced by environmental bacteria have been analyzed by modern chemical and material science methods. Research on actinide biomaterials has focused on the biomineralization of a few chemical forms of uranium, neptunium, and plutonium. The materials produced are molecular complexes, microcrystalline minerals (most commonly oxides and phosphates) within cells and biofilms, and mineral adsorbates. The actinide biomaterials that emerge from this new research area will impact nuclear waste isolation and increase our understanding of environmental and geological metal cycles and may yield new bioremediation methods and industrially useful materials.

Plutonium has no known biological utility, yet it has the potential to interact with bacterial cellular and extracellular structures that contain metal-binding groups, to interfere with the uptake and utilization of essential elements, and to alter cell metabolism. These interactions can transform plutonium from its most common forms, solid, mineral-adsorbed, or colloidal Pu(IV), to a variety of biogeochemical species that have much different physico-chemical properties. Organic acids that are extruded products of cell metabolism can solubilize plutonium and then enhance its environmental mobility, or in some cases facilitate plutonium transfer into cells. Phosphate- and carboxylate-rich polymers associated with cell walls can bind plutonium to form mobile biocolloids or Pu-laden biofilm/mineral solids. Bacterial membranes, proteins or redox agents can produce strongly reducing electrochemical zones and generate molecular Pu(III/IV) species or oxide particles. Alternatively, they can oxidize plutonium to form soluble Pu(V) or Pu(VI) complexes. This paper reviews research on plutonium-bacteria interactions and closely related studies on the biotransformation of uranium and other metals.

Highly toxic beryllium(II) is divalent metal ion with a high charge density, making it a potential target for binding to bio-molecules rich in O donor groups. In aqueous solution Be2+binds to ATP and ADP to form 1:1 Be2+:ATP and Be2+:ADP complexes in relatively acidic media. At neutral pH the complex formed undergoes hydrolysis. Be2+binding to ATP and ADP is much stronger than Ca2+and Mg2+binding. The high affinity of Be2+toward ATP and ADP binding suggests a mechanism relevant to understanding the in vivochemical toxicity of this metal.

In this mini-review we describe selected aspects of the coordination chemistry relevant to siderophore mediated iron transport and bioavailability. Specific emphasis is placed on a discussion of in vitrokinetic and thermodynamic data that are relevant to elucidating possible in vivomechanisms for environmental iron acquisition by microbial cells.

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