SbO(OH)2(IO3): The First Polar Sb5+‐Iodate with a Strong Second‐Harmonic Generation Response and a Wide Bandgap

Abstract Widening the bandgaps while maintaining a strong second harmonic generation response has always been a research hotspot in the field of nonlinear optical iodate materials. A strategy involving covalent bonding is proposed that leverages the high valent later main group cation to construct iodates with predominantly covalent interactions. By using BiO(IO 3 ) as a template, the first Sb 5+ ‐containing polar iodate, SbO(OH) 2 (IO 3 ) is successfully isolated. The introduction of the two hydroxide anions led to the reduction of layered BiO(IO 3 ) into 1D SbO(OH) 2 (IO 3 ) in which two corner‐sharing SbO 4 (OH) 2 octahedra are further bridged by an iodate group. The covalently bonded [SbO(OH) 2 ] + chains and the optimal packing fashion of the asymmetric IO 3 − groups generate a very strong second harmonic generation signal of 14 times that of KH 2 PO 4 . Furthermore, SbO(OH) 2 (IO 3 ) exhibits a wide bandgap of 4.14 eV and a high laser induced damage threshold [27.9 × AgGaS 2 , 0.2 × KH 2 PO 4 (10 ns, 10 Hz)].