Synthesis, Structure, and Characterization of d0 Transition-Metal Iodate: BaTi(IO3)6•0.5H2O

A new noncentrosymmetric (NCS) d(0) transition-metal (TM) iodate BaTi(IO3)(6)center dot 0.5H(2)O has been successfully synthesized by the typical hydrothermal method. The single-crystal X-ray diffraction shows that BaTi(IO3)(6)center dot 0.5H(2)O crystallizes in the polar trigonal space group R3 (no. 146) with a = b = 11.1920(12) angstrom, c = 24.006(3) angstrom. The reported compound features zero-dimensional (0D) [Ti(IO3)(6)](2-) clusters that are separated by Ba2+ cations and bound water in the structure. By comparing BaTi(IO3)(6)center dot 0.5H(2)O with the centrosymmetric (CS) alpha- and beta-BaTi(IO3)(6) that were reported before, it can be found that the bound water plays an important role for the formation of NCS structure for BaTi(IO3)(6)center dot 0.5H(2)O . In addition, based on the powder second harmonic (SHG) measurement, BaTi(IO3)(6)center dot 0.5H(2)O can achieve type-I phase matching with a moderate SHG effect (similar to 1 X KDP). The source of SHG effect was analyzed by dipole moment calculation and structure comparison. UV-vis-NIR diffuse reflectance spectroscopy, infrared spectroscopy, and thermogravimetric measurements are also presented.