Ba10Zn7M6Q26: Two New Mid-infrared Nonlinear Optical Crystals with T2 Supertetrahedron 3D Framework

Two new mid-infrared (MIR) nonlinear optical (NLO) chalcogenide crystals, Ba10Zn7In6S26 (1) and Ba10Zn7Ga6Se26 (2) were discovered by traditional solid state reactions. Compounds 1 and 2 are isostructural, and they represent a novel three-dimensional (3D) framework made by apex-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 in the tunnels. Among them, 1 shows attractive MIR NLO properties with 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 laser damage threshold (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 theo...