Solvothermal Syntheses and Characterizations of Two New Sliver Selenidoantimonates of Ag3SbSe3 and Ag5SbSe4

摘要

Two new sliver selenidoantimonates,namely,Ag_3SbSe_3 and Ag_5SbSe_4,were prepared under mid solvothermal conditions and structurally characterized by single-crystal X-ray diffraction studies.Ag_3SbSe_3 crystallizes in the orthorhombic space group Pnma(No.62) with a =8.2414(12),b = 11.4925(17),c = 21.220(3) A,V= 2009.8(5) A^3 and Z= 12.Its structure belongs to the β-Ag_3AsSe_3 type and features a 3D complex network composed of distorted trigonal planar AgSe_3 and tetrahedral AgSe_4 units as well as SbSe_3 trigonal pyramids.Ag_5SbSe_4 crystallizes in the orthorhombic system,nocentrosymmetric space group Cmc2_1(No.36) with a = 8.1148(6),b =12.9829(10),c = 8.7017(7) A,V= 916.76(12) A^3 and Z = 4.Its structure adopts the Ag_5SbS_4 type and features a 3D framework based on trigonal planar AgSe_3 units and SbSe_3 trigonal pyramids.The results of optical absorption spectra and band structure calculations indicate that the title compounds are narrow band-gap semiconductors.