title: Reinvestigation of the uranium(3.5+) rare-earth oxysulfides "(UO)2LnS3" (Ln = Yb, Y).
abstract: Dark-red square plates of the previously reported compounds "(UO)(2)LnS(3)" (Ln = Yb, Y) have been synthesized by solid-state reactions of UOS and YbS or Y(2)S(3) with Sb(2)S(3) as a flux at 1273 K. The structure of these isotypic compounds was reinvestigated by single-crystal X-ray diffraction methods and an inductively coupled plasma experiment. The actual formula of "(UO)(2)LnS(3)" (Ln = Yb, Y) is (U(0.5)Ln(0.5)O)(2)LnS(3), that is, ULn(2)O(2)S(3), which can be charge-balanced with U(4+) and Ln(3+). The layered structure comprises (U/Ln)O(4)S(4) square antiprisms alternating with LnS(6) octahedra. U and Ln1 atoms disorder on the eight-coordinate metal position, but Ln2 atoms occupy the six-coordinate metal position exclusively. UYb(2)O(2)S(3) is a modified Curie-Weiss paramagnet between 293 and 32 K, below which part of the paramagnetic moments go through a possible ferromagnetic transition. The band gaps of ULn(2)O(2)S(3) (Ln = Yb, Y) are around 2 eV.
authors.affiliation: Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, USA.
authors.forename: Geng Bang
authors.initials: GB
authors.lastname: Jin
authors.forename: Eun Sang
authors.initials: ES
authors.lastname: Choi
authors.forename: James A
authors.initials: JA
authors.lastname: Ibers