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

Two new rare-earth metal chalcogenides, namely RbLu5Te8and CsMnGdTe3, have been successfully synthesized under high-temperature solid-state reaction conditions and structurally characterized by single-crystal X-ray diffraction analysis. RbLu5Te8belongs 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) ?, β = 103.89(2)°, V = 975.4(4) ?3, whereas CsMnGdTe3crystallizes 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) ? and V = 888.4(3) ?3. 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 CsMnGdTe3consists 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.