Yang, GangLi, LonghuaWu, ChaoHumphrey, MarkZhang, Chi2020-09-210020-1669http://hdl.handle.net/1885/210969Two interesting non-centrosymmetric metal chalcogenides, Rb2Ag3Sb3S7 and Cs2Ag3Sb3S7, were synthesized by an ionothermal approach. Crystals of compounds Rb2Ag3Sb3S7 and Cs2Ag3Sb3S7 possess isomorphic configuration, consisting of two-dimensional (2D) anionic networks ∞[Ag3Sb3S7]2−, which are split by alkali-metal M+ cations. The band gaps are 2.11 and 2.02 eV for Rb2Ag3Sb3S7 and Cs2Ag3Sb3S7, respectively. Second-harmonic generation (SHG) studies revealed that Rb2Ag3Sb3S7 affords a powder SHG performance of ∼0.5 × AgGaS2 with type-I phase matching, while Cs2Ag3Sb3S7 shows a slightly stronger SHG performance of ∼0.6 × AgGaS2 with type-I phase matching. Both compounds possess broad transparency ranges (∼0.6− 20 μm), suggesting their potential as infrared (IR) nonlinear optical (NLO) materials. The laser damage thresholds (LDTs) of both Rb2Ag3Sb3S7 and Cs2Ag3Sb3S7 are about 2.3 × AgGaS2. The calculated birefringence indexes Δn are 0.1885 and 0.1944 at 1.064 μm, respectively, which are sufficiently large enough to achieve phase matching. Theoretical studies using density functional theory have been implemented to further understand the relationship between their NLO properties and band structures.This research was financially supported by the National Natural Science Foundation of China (51432006), the Ministry of Education of China for the Changjiang Innovation Research Team (IRT13R24), the Ministry of Education and the State Administration of Foreign Experts Affairs for the 111 Project (B13025), the Innovation Program of Shanghai Municipal Education Commission, the Innovation Research Team and Key Basic Research Plan of Tongji University. M.G.H. thanks the Australian Research Council for support (DP170100411).application/pdfen-AU© 2019 American Chemical Society201910.1021/acs.inorgchem.9b012622020-06-23