BiO(IO3): A New Polar Iodate that Exhibits an Aurivillius-Type (Bi2O2)2+ Layer and a Large SHG Response

A new noncentrosymmetric (NCS) and polar material containing two lone-pair cations, Bi3+ and I5+, and exhibiting an Aurivillius-type (Bi2O2)2+ layer has been synthesized and structurally characterized. The material, BiO(IO3), exhibits strong second-harmonic generation (SHG), ∼12.5 × KDP (or ∼500 × α-SiO2), using 1064 nm radiation, and is found in the NCS polar orthorhombic space group Pca21 (No. 29). The structure consists of (Bi2O2)2+ cationic layers that are connected to (IO3)− anions. The macroscopic polarity, observed along the c-axis direction, may be attributed to the alignment of the IO3 polyhedra. In addition to the crystal structure and SHG measurements, polarization and piezoelectric measurements were performed, as well as electronic structure analysis.