Low temperature syntheses can be used to obtain complex U(IV) containing fluorides; however, these reactions are very sensitive to the choice of starting reagents. Using different precursors and reaction conditions that stabilize the reduced U(IV) state, we have prepared numerous simple fluorides, such as U3F12●H2O, and complex fluorides, such as RbU3F13, Na4MU6F30 and Na4M+2U6F30, as well as recently a new fluoride family Cs2MU3F16, exhibiting long range magnetic order. To extend this series, we successfully prepared Na3MCe6F30 (M = Al3+, Ga3+, V3+, Cr3+, Fe3+). Given the similar ionic radii of Ce4+ and Pu4+, we used the cerium fluoride phases as a guide to predict which of the plutonium fluorides could be formed, and our initial work on this system has successfully resulted in the novel composition Na3FePu6F30 which was obtained from mild hydrothermal synthesis methods. In addition Na3GaPu6F30 and Na3AlPu6F30 were successfully prepared. Attempts to incorporate larger divalent ions into the structure such as Mn2+ have resulted in the nominal disordered composition Na2.4Mn1.6Pu6F30; an unanticipated result considering that electroneutrality necessitates disordered Mn2+/Mn3+ in the structure. This presentation will focus on the crystal growth approach, structures and magnetic properties of the obtained phases.

New quaternary uranium and plutonium fluorides crystallized via mild hydrothermal methods

ACS Fall 2020 Virtual Meeting

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