摘要： Two new mid-infrared (MIR) nonlinear optical (NLO) chalcogenide crystals, Ba10Zn7In6S26, 1 and Ba10Zn7Ga6Se26, 2 are discovered by traditional solid state reactions. 1 and 2 are isostructural and they represent a novel three-dimensional (3D) framework made by apexe-sharing T2 supertetrahedron 2D layers that are stacked alternately by another kind of T2 supertetrahedra though sharing apexes along the c direction, with T1 tetrahedra inserting in the tunnels and Ba2+ cations locating both in the voids and tunnels. Among them, 1 shows attractive MIR NLO properties of a wide band gap of 3.0 eV, a strong second harmonic generation (SHG) signal about 4.1 times that of the commercial AgGaS2 at particle sizes of 30–46 μm under a 2.05 μm laser radiation, and a high LDT of 37.2 times that of benchmark AgGaS2 at particle sizes of 150–210 μm under a 1.064 μm laser radiation. This distinguishes 1 as a new promising MIR NLO material. In addition, the density functional theory (DFT) analyses suggest that the SHG response of 1 comes mainly from the electronic transitions from S 3p to Ba 5d, Zn 4s, Zn 3d, In 5s, In 5p states.