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Christian Juillerat1 Hans-Conrad zur Loye1

1, University of South Carolina, Columbia, South Carolina, United States

Uranyl phosphates are important for understanding actinide chemistry for applications in the field of nuclear waste storage, particularly because they are prominent in nature making up 25% of known uranyl minerals and because uranyl phosphates have lower solubilities compared to other uranyl minerals. The molten flux crystal growth method can be used to make a variety of new uranyl phosphate structures including materials featuring new geometrical isomers of the phosphoruranylite topology, cation-cation interactions (CCIs), and three-dimensional frameworks. CCIs are rare in uranyl materials and occur in less than 2% of uranyl structures while CCIs are observed in approximately 50% of neptunyl materials. Three-dimensional structures are also less common due to the tendency of the U(VI) polyhedra to bond through the axial oxygens to form sheet based structures. The presentation will focus on the synthesis, crystal growth, and overall crystal chemistry of new uranyl phosphate materials with unique structural features including: Cs4(PO4)2[(UO2)3O2], Cs6(PO4)4[(UO2)7O4], Cs2Na4(PO4)2[(UO2)5O5], and K4(PO4)2[(UO2)3O2].

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