Ba2[WO3F(IO3)][WO3F2]: the first polar fluorinated tungsten iodate featuring a direct W–O–I bond

Abstract

The introduction of the transition metal cations with d⁰ electron configurations and F in the iodate systems generates a new polar compound, Ba₂[WO₃F(IO₃)][WO₃F₂], which features the first example of a direct W–O–I bond in the structure. It exhibits excellent properties, including a large second harmonic generation response (∼3.5 × KH₂PO₄), a wide visible and mid-infrared transparency region (0.28–10.74 μm), and a moderate birefringence of 0.061@532 nm.