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

The first metal iodate fluoride, Bi(IO₃)F₂, with a strong second harmonic generation (SHG) effect has been prepared. Bi(IO₃)F₂ crystallizes in the polar space group C2 and features a three‐dimensional BiF₂]⁺ cationic framework with IO₃ groups capping the inner walls of the one‐dimensional tunnels. This BiF₂]⁺ cationic framework acts as a template for the assembly of the polar IO₃ units in a favorable superposed fashion, which leads to the polar structure of the material. Bi(IO₃)F₂ 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 KH₂PO₄ (KDP) under 1064 nm laser radiation and the same as that of KTiOPO₄ (KTP) under 2.05 μm laser radiation. Preliminary investigations indicate that Bi(IO₃)F₂ is a promising nonlinear optical material in the visible and mid‐IR region.