Lead Mixed Oxyhalides Satisfying All Fundamental Requirements for High‐Performance Mid‐Infrared Nonlinear Optical Materials

Abstract To design high‐performance mid‐infrared (mid‐IR) nonlinear optical (NLO) materials, we have focused on the combination of a heavy metal lone pair cation, Pb 2+ and mixed oxyhalides. A systematic investigation in PbO‐PbCl 2 ‐PbBr 2 system led us to discover the first examples of NLO lead mixed oxyhalides, namely, Pb 13 O 6 Cl 4 Br 10 , Pb 13 O 6 Cl 7 Br 7 , and Pb 13 O 6 Cl 9 Br 5 . All the reported materials have remarkably comprehensive properties including broad IR transparency (up to 14.0 μm), qualified second harmonic generation (SHG) responses (0.6–0.9×AgGaS 2 ), wide band gaps (3.05–3.21 eV), and ease of crystal growth. Interestingly, a centimeter‐sized single crystal (2.9×1.3×0.5 cm 3 ) of Pb 13 O 6 Cl 9 Br 5 revealing a wide transparent range (0.384–14.0 μm) and high laser damage threshold (LDT) (14.6×AgGaS 2 ) has been successfully grown in an open system. The study suggests that all the reported mixed oxyhalides are outstanding candidates for mid‐IR NLO materials.