SbO(OH) 2 (IO 3 ): The First Polar Sb 5+ -Iodate with a Strong Second-Harmonic Generation Response and a Wide Bandgap.

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)].
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