Synthesis and Characterization of A New Open-Framework Cobalt Phosphate: Cs2Co3(HPO4)(PO4)2·H2O

SrBi2Se4 was synthesized at 945°C and its structure was determined using single-crystal X-ray diffraction data obtained at 165 K. SrBi2Se4 is isotypic to 12-BaBi2S4 and Eu1.1Bi2S4. The compound crystallizes in P63/m (Z=12) with a=25.970(2) ? and c=4.2437(3) ?. Final R1=0.0630 and wR2=0.1246 (I>2(I)). The coordination environments of Bi are distorted Se octahedra. These octahedra build up a uniaxial three-dimensional network with tunnels along the z direction, which are filled by Sr2+. There is also a second tunnel along the z direction which is partially occupied by Bi atoms. The coordination spheres of Sr are bicapped trigonal prisms of Se. Transport measurements indicate that SrBi2Se4 is semiconducting. This work adds one highsymmetry compound to the family of complex chalcogenides, in which low-symmetry compounds are common.