NaGa<sub>3</sub>Se<sub>5</sub>: An Infrared Nonlinear Optical Material with Balanced Performance Contributed by Complex {[Ga<sub>3</sub>Se<sub>5</sub>]<sup>−</sup>}<sub>∞</sub> Anionic Network
Qian-Ting Xu, Shanshan Han, Jia-Nuo Li, Sheng‐Ping Guo
Abstract
Second-order nonlinear optical (NLO) materials are extensively applied in laser-related techniques. For developing IR NLO materials, chalcogenides are the main candidates. Here, NaGa3Se5 was explored as inspired by its unique anionic structure. It crystallizes with the orthorhombic chiral P212121 structure, featuring 12 types of GaSe4 tetrahedra built into a three-dimensional {[Ga3Se5]−}∞ anionic network, representing a new NLO-functional motif. NaGa3Se5 exhibits large and phase-matchable NLO response 1.37 × AgGaS2. It has the largest band gap among the noncentrosymmetric A–MIII–Se (A = alkali metal; M = Ga, In) compounds. The NLO properties’ origin is explored via theoretical analysis. The success of NaGa3Se5 contributes a practical case for exploring new NLO materials.