First Investigation of Nonlinear Optical Oxychalcogenide with Three‐Dimensional Anionic Framework and Special Windmill‐Like Functional Motifs†

Comprehensive Summary Oxychalcogenides have been drawn much attention to be explored as nonlinear optical (NLO) materials in recent years. To date, all the NLO oxychalcogenides crystallize in low dimensional structures. Herein, a new oxysulfide K 2 Ba 0.5 Ga 9 O 2 S 13 was obtained via three‐dimensional (3D) {[Ga 9 O 2 S 13 ] 3– } ∞ polyanionic framework. As the first oxychalcogenide with 3D NLO‐acitve polyanionic framework, K 2 Ba 0.5 Ga 9 O 2 S 13 has a wide band gap of 3.72 eV, and exhibits a high laser‐induced damage threshold (LIDT, 17 × AgGaS 2 ). It presents moderate phase‐matchable NLO response of 0.5 × AgGaS 2 at 2.1 μm and 2 × KH 2 PO 4 at 1.064 μm. The theoretical calculation results indicate that the NLO response is mainly contributed from [Ga(2)S 4 ] unit‐built [Ga(2) 3 S 10 ] windmill‐like motif. This work may stimulate the exploration of more NLO oxychalcogenides with balanced performances.