Synthesis and Crystal Structure of the γ‐Modifications of US2 and USe2

Abstract

AbstractWe report on γ‐US2 and γ‐USe2 which may be synthesized by a presumably topotactic reaction from the corresponding U3X5 compounds and elementary chalcogen. γ‐USe2 can also be prepared by a high pressure transformation of α‐USe2 at 4 GPa and 773 K. The structure of the γ phases could be determined and refined by a Rietveld procedure from powder data. They crystallize in an anti‐Fe2P‐type arrangement. Unusual features of these structures and a possible reaction mechanism for the formation of the compounds are discussed.