Two Barium Gold Iodates: Syntheses, Structures, and Properties of Polar BaAu(IO3)5 and Nonpolar HBa4Au(IO3)12 Materials

Two new barium gold iodates, namely, BaAu(IO3)5 and HBa4Au(IO3)12, have been prepared. BaAu(IO3)5 crystallizes in the polar space group Pca21, whereas HBa4Au(IO3)12 crystallizes in the centrosymmetric space group P21/c. BaAu(IO3)5 consists of unique polar [Au(IO3)4]− anions whose four iodate groups are located at both sides of the AuO4 plane and the polarity points in the [001̅] direction. BaAu(IO3)5 displays strong second-harmonic-generation (SHG) effects about 0.6KTiOPO4 (KTP) and is phase-matchable. Thermal properties, optical spectra analyses, and theoretical calculations are also reported.