Bi(IO₃)F₂: The First Metal Iodate Fluoride with a Very Strong Second Harmonic Generation Effect

The first metal iodate fluoride, Bi(IO 3 )F 2 , with a strong second harmonic generation (SHG) effect has been prepared. Bi(IO 3 )F 2 crystallizes in the polar space group C2 and features a three‐dimensional [BiF 2 ] + cationic framework with IO 3 groups capping the inner walls of the one‐dimensional tunnels. This [BiF 2 ] + cationic framework acts as a template for the assembly of the polar IO 3 units in a favorable superposed fashion, which leads to the polar structure of the material. Bi(IO 3 )F 2 displays a rather wide transmittance window (0.3–11 μm) and exhibits a very strong SHG response that is about 11.5 times larger than that of KH 2 PO 4 (KDP) under 1064 nm laser radiation and the same as that of KTiOPO 4 (KTP) under 2.05 μm laser radiation. Preliminary investigations indicate that Bi(IO 3 )F 2 is a promising nonlinear optical material in the visible and mid‐IR region.