A Lead Mixed Halide with Three Different Coordinated Anions and Strong Second‐Harmonic Generation Response

Abstract Nonlinear optical (NLO) crystals are widely applied in information technology, micro‐manufacturing and medical treatment. Herein, a new lead mixed halide with strong second‐harmonic generation (SHG) response, Cs3Pb2(CH3COO)2Br3I2, has been designed and rationally synthesized. Cs3Pb2(CH3COO)2Br3I2 represents the rare NLO crystal featuring that three different anions (I−, Br− and O2−) simultaneously coordinate the Pb(II) atom to form a severely distorted [PbBr2I2O2] polyhedron with a large polarizability. Remarkably, Cs3Pb2(CH3COO)2Br3I2 not only exhibits a very strong phase‐matching SHG response of 9×KH2PO4 (KDP), but also possesses a large birefringence (0.27@1064 nm) and high laser damage threshold (LDT). The strong SHG effect of Cs3Pb2(CH3COO)2Br3I2 mainly originates from the oriented arrangement of [Pb2Br3I2] chains. This study points out an effective strategy to develop new NLO crystals with strong SHG response.