Centimeter-sized Zn(NH3)CO3 is a “three-in-one” UV nonlinear optical crystal, featuring a Chinese-knot-like framework and great optical performance.

Nonlinear optical (NLO) crystals featuring strong second-harmonic generation (SHG) response and suitable birefringence to achieve phase-matching are in urgent demand in industrial and commercial applications. Based on the substitution strategy,...

Nonlinear optical (NLO) materials are playing an increasingly vital role in laser science and technology. Herein, we report a new lead formate, KCs2Pb2(HCOO)2Cl5, successfully synthesized by using mild mix-solvothermal methods. By the anionic substitution of a [CH3COO] group with a [HCOO] group, the dipole moment of the distorted [PbCl4O2] polyhedron is increased. In contrast, polarization from the anionic group and the volume of the unit cell are reduced. Hence, KCs2Pb2(HCOO)2Cl5 possesses a strong second-harmonic-generation (SHG) response of 4.2 times that of KH2PO4 (KDP), a transparent window covering 0.43–1.87 μm, a large band gap of 3.52 eV, and moderate birefringence (0.11@1064 nm). Systematic theoretical calculations illustrate the origin of the linear and nonlinear optical properties of KCs2Pb2(HCOO)2Cl5. This research provides a viable strategy for the design and synthesis of new NLO crystals.