Dimensionality Reducing from Three-dimensional RbLu5Te8 to Two-dimensional CsMnGdTe3:Syntheses,Crystal and Electronic Structures

Two new rare-earth metal chalcogenides,namely RbLu5Te8 and CsMnGdTe3,have been successfully synthesized under high-temperature solid-state reaction conditions and structurally characterized by single-crystal X-ray diffraction analysis.RbLu5Te8 belongs to the monoclinic space group C2/m(no.12)with two formula units in a unit cell:a=22.075(5),b=4.2987(8),c=10.588(2)A,β=103.89(2)°,V=975.4(4)A3,whereas CsMnGdTe3 crystallizes in the orthorhombic space group Cmcm(no.63)with four formula units in a unit cell:a=4.4872(8),b=16.769(3),c=11.807(2)A and V=888.4(3)A3.In the structure of RbLu5Te8,face-,edgeand vertex-sharing[LuTe6]octahedra are interconnected to produce a three-dimensional(3D)framework with Rb^+lying in the tunnels.The crystal structure of CsMnGdTe3 consists of two-dimensional(2D)[MnGdTe3]^–layers of edge-and vertex-sharing[GdTe6]octahedra with Mn atoms filling the tetrahedral interstices,which stack along the b-axis.The Cs atoms are located between the[MnGdTe3]^–layers and surrounded by eight Te atoms to form a[CsTe8]bicapped trigonal prism.Moreover,theoretical studies have aided the understanding of their electronic structures.