KBi(SeO4)(IO3)Cl: A mixed-anion oxychloride with three types of building units in one structure

A novel mixed-anion oxychloride, KBi(SeO4)(IO3)Cl, has been hydrothermally synthesized and structurally characterized. The compound crystallizes in the monoclinic space group of P21/c with cell parameters of a = 7.8802(2) angstrom; b = 10.8088(2) angstrom, c =10.1364(2) angstrom, beta = 112.849(1)degrees, V = 795.62(3) angstrom 3, and Z = 4. KBi(SeO4)(IO3) Cl exhibits a three-dimensional tunnel framework that is composed of three types of atomic groups, i.e., tetrahedral SeO4, trigonal pyramidal IO3, and polyhedral BiO6Cl. Both IO3 pyramid and BiO6Cl polyhedron are in strongly acentric coordination due to the influence of I5+ and Bi3+ lone electron pairs. The measurement of UV-vis-NIR spectra for powder KBi(SeO4)(IO3)Cl indicates that the material is a wide band gap semiconductor with Eg = 3.9 eV. Theoretical analysis shows that the electron transition from Bi 6p to O 2p states in the BiO6Cl unit dominates the optical absorption edge. Thermal stability and IR spectrum were also analyzed for the material.