NaGa 3 Se 5 : An Infrared Nonlinear Optical Material with Balanced Performance Contributed by Complex {[Ga 3 Se 5 ] - } ∞ Anionic Network.

Second-order nonlinear optical (NLO) materials are extensively applied in laser-related techniques. For developing IR NLO materials, chalcogenides are the main candidates. Here, NaGa 3 Se 5 was explored as inspired by its unique anionic structure. It crystallizes with the orthorhombic chiral P 2 1 2 1 2 1 structure, featuring 12 types of GaSe 4 tetrahedra built into a three-dimensional {[Ga 3 Se 5 ] - } ∞ anionic network, representing a new NLO-functional motif. NaGa 3 Se 5 exhibits large and phase-matchable NLO response 1.37 × AgGaS 2 . It has the largest band gap among the noncentrosymmetric A-M III -Se (A = alkali metal; M = Ga, In) compounds. The NLO properties' origin is explored via theoretical analysis. The success of NaGa 3 Se 5 contributes a practical case for exploring new NLO materials.