Synthesis, crystal structure and optical properties of two new layered cadmium iodates: Cd(IO3)X (X=Cl, OH)

Systematic explorations of new compounds in the cadmium iodate system by hydrothermal reactions led to two layered iodates, namely, Cd(IO3)X (X=Cl, OH). Cd(IO3)Cl crystallizes in the orthorhombic space group Cmca (No. 64) whereas Cd(IO3)(OH) crystallizes in the orthorhombic space group Pnma (No. 62). Cd(IO3)Cl displays a unique double layered structure composed of [Cd−O3Cl]n∞1 chains. Cadmium octahedrons form a 1D chain along the a-axis through edge sharing, and such chains are further interconnected via IO3 groups to form a special double layer on (020) plane. Cd(IO3)(OH) also exhibits a layered structure that is composed of cadmium cations, IO3 groups and hydroxyl ions. Within a layer, chains of CdO6 edge-shared octahedra are observed along the b-axis. And these chains are connected by IO3 groups into a layer parallel to the bc plane. Spectroscopic characterizations, elemental analysis, and thermogravimetric analysis for the reported two compounds are also presented.