Synthesis and structural characterization of the new compound UEr2O2S3 and the evidence for the old compound U2ErO2S3

Black square plates of the new compound UEr2O2S3 have been synthesized by the reaction of UOS, Er, and S with an Sb2S3 flux at 1273 K. The structure of UEr2O2S3 has been solved and refined from single-crystal X-ray diffraction data. UEr2O2S3 forms a layered structure with layers of edge-sharing ErS6 octahedra and double layers of disordered (U/Er)O4S4 square antiprisms. Upon reexamination of the previously reported X-ray data for the U3.5+ compound U2ErO2S3 we conclude that it also may be characterized as the U4+ compound UEr2O2S3.