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, Pb2BO3I, synthesized by a straightforward hydrothermal method. The Pb2BO3I chemical formula conceals that the compound exhibits a structure similar to the well-established KBe2BO3F2 (KBBF), which we show supports the highest second-harmonic generation (SHG) at 1064 nm in the KBBF family, 10 x KH2PO4 (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.