Cd4SiQ6 (Q= S, Se): Ternary Infrared Nonlinear Optical Materials with Mixed Functional Building Motifs

Two ternary infrared nonlinear optical materials Cd4SiS6 (1) and Cd4SiSe6 (2) with polar space group Cc were obtained by mixing d(10) configurations-central tetrahedra motifs and nonlinear optical (NLO)-active distorted M(IV)Q(4]) tetrahedra motifs in a non-alkaline earth metals-containing system. They exhibited an interesting three-dimensional (3D) framework structure, and millimeter-level single crystals were successfully grown by a chemical transport reaction. Comprehensive optical measurements indicated that they achieve coexistence of good second-harmonic generation (SHG) responses (1.3 and 1.9 x AgGaS2 at 74-106 mu m particle size) and high laser-induced damage thresholds (8.6 and 7.1 x AgGaS2 at 1064 nm laser) and wide infrared (IR) transparent regions (0.45-17.6 mu m for 1, 0.64-20.3 mu m for 2). Furthermore, theoretical studies revealed that their SHG effects originate from two functional building motifs (FBMs) CdQ(4) and SiQ(4) tetrahedra, shedding light on the exploration of new IR NLO materials with mixed FBMs.