Three-in-One Tetrahedral Functional Units Constructing Diamondlike Ag₂In₂SiS_3.06Se_2.94 with High-Performance Nonlinear-Optical Activity

Abstract

Exploration of new functional materials with enhanced performance from known ones is always an attractive strategy. A new infrared (IR) nonlinear-optical (NLO) mixed chalcogenide Ag2In2SiS3.06Se2.94 (1), was obtained through partial congener substitution originated from Ag2In2SiS6 (0). 1 crystallizes in the monoclinic space group Cc, and its three-dimensional (3D) polyanionic network is composed of {[In4Si2Se5(S/Se)11]12–}∞ helical chains sharing S/Se(5) corner atoms with cavities embedded with counterion Ag+ ions. It exhibits a much enhanced NLO response compared to that of 0, reaching 1.1 × AgGaS2. Further theoretical analysis results indicate that the large NLO response can be attributed to the synergistic effect of AgQ4 and InQ4 tetrahedral functional motifs. This work not only reports a new high-performance IR NLO material but also enriches the partial ion substitution strategy to obtain new functional materials.

KREP2S6 (RE = Sm, Gd, Tb, Dy): A Series of Polar Rare-Earth Thiophosphates with High Laser-Induced Damage Thresholds and Moderate Nonlinear-Optical Responses Synergistically Contributed by Isolated P2S6 Units and {[RE2S15]24–}∞ Layers

“…However, their intrinsic drawbacks like small laser-induced damage threshold (LIDT) or two-photon absorption restrict their applications. − Hence, exploration of IR NLO materials is still urgent and necessary. As an excellent IR NLO material, it is imperative to satisfy a series of requirements including high LIDT, large second-harmonic-generation (SHG) intensity, phase-matching (PM), etc. − Nowadays, many methods are used to develop IR NLO crystals, for example, (1) derivatives from AgGaQ 2 (Q = S, Se) like (Na 0.74 Ag 1.26 )­BaSnS 4 , Li 2 BaGeS 4 , and Na 2 Ga 3 In 3 Se 10 ; (2) normal diamond-like structures like Li 4 MgGe 2 S 7 Ag 2 In 2 SiS 3.06 Se 2.94 , and Ag 2 CdGeS 4 , in which MQ 4 (M = Ga, Ge, Cd, Zn, Si, Hg, In) tetrahedra are aligned along a special direction to generate a good NLO effect; (3) salt-inclusion chalcohalides through the host and guest parts coregulating the structures, which have achieved great success, − and (4) partial-ion-substitution-induced symmetric break from centrosymmetric (CS) to noncentrosymmetric (NCS) structures and realization of SHG activities, such as Sn 7 Br 10 S 2 , (K 0.38 Ba 0.81 )­Ga 2 Se 4 , and K 3 Ga 3 (Ge 7– x M x )­Se 20 (M = Si, Sn) …”