Solid-State Preparation, Structural Characterization, Physical Properties and Theoretical Studies of a Series of Novel Rare-earth Metal-Chalcogenides with Unprecedented Closed Cavities

摘要： Multinary rare-earth metal-chalcogenides have aroused great concern owing to their special structure characteristics and diverse physical functions. In this work, five novel rare-earth chalcogenides adopt the formula Cs2[RE8InS14] (where RE = Ho–Lu), has been obtained by the elementals mixture in CsCl flux at 1273 K. They are isotype and belong to the orthorhombic Cmca (no. 64) [a = 15.711(7)–15.385(2) ?, b = 22.232(2)–21.786(2) ?, c = 15.483(5)–15.244(2) ?, V = 5408.4(4)–5130.1(7) ?3 and Z = 8], exhibiting a dense 3D [RE8InS14] framework consisting of RES6 octahedron and discrete InS4 tetrahedron. The large closed-cavities Cs4@S26 are far apart embedded within the network along bc-plane, which is discovered for the first time. The band gaps from 2.45 to 2.72 eV for Cs2[RE8InS14] were deduced from the UV?Vis–NIR spectroscopy based on the Kubelka-Munk function. Magnetic test indicates that the Cs2[RE8InS14] (RE = Ho–Yb) compounds possess para-magnetism above 50K. In addition, the solid-state preparation, structural characterization, theoretical studies together with a structure–G/H ratio relationship (G = atomic number of guest metals; H = atomic number of host metals) are also presented.