Pb2BO3I: A Borate Iodide with the Largest Second‐Harmonic Generation (SHG) Response in the KBe2BO3F2 (KBBF) Family of Nonlinear Optical (NLO) Materials

Borate halides are an ideal materials class from which to design high-performance nonlinear optical (NLO) materials. Currently, borate fluorides, chlorides, and bromides are extensively investigated while borate iodide materials discovery remains rare because of the perceived synthetic challenges. We report a new borate iodide, Pb2 BO3 I, synthesized by a straightforward hydrothermal method. The Pb2 BO3 I chemical formula conceals that the compound exhibits a structure similar to the well-established KBe2 BO3 F2 (KBBF), which we show supports the highest second-harmonic generation (SHG) at 1064 nm in the KBBF family, 10 × KH2 PO4 (KDP), arising from the inclusion of Pb2+ and I- and the crystal chemistry. Our work shows that KBBF-related compounds can be synthesized incorporating iodide and exhibit superior NLO responses.