Two Barium Gold Iodates: Syntheses, Structures, and Properties of Polar BaAu(IO 3 ) 5 and Nonpolar HBa 4 Au(IO 3 ) 12 Materials.

Two new barium gold iodates, namely, BaAu(IO3 )5 and HBa4 Au(IO3 )12 , have been prepared. BaAu(IO3 )5 crystallizes in the polar space group Pca21 , whereas HBa4 Au(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.