AMnAs<sub>3</sub>S<sub>6</sub> (A = Cs, Rb): Phase-Matchable Infrared Nonlinear Optical Functional Motif [As<sub>3</sub>S<sub>6</sub>]<sup>3–</sup> Obtained via Surfactant–Thermal Method
Run Ye, Bin‐Wen Liu, Xiao‐Ming Jiang, Jian Lü, Hui‐Yi Zeng, Guo‐Cong Guo
Abstract
Exploration of a new nonlinear optical (NLO)-active functional motif is important in the rational design of promising infrared (IR) NLO materials. Compared with typical tetrahedral MQ4 (M = IIB, III, IV metals; Q = S, Se) motifs, MQ3 (M = As, Sb) pyramids favor high second-harmonic generation (SHG) efficiency while frequently hindering phase matching (PM) because of excessively large optical anisotropy. The surfactant–thermal method was first adopted to achieve PM in MQ3-containing systems and synthesize mixed covalent–ionic IR NLO materials. Two new thioarsenates of AMnAs3S6 (A = Cs, Rb) exhibiting strong PM SHG efficiencies comparable to commercial AGS and laser-induced damage thresholds of one order higher than AGS were obtained. The [As3S6]3– unit in their structures is an unprecedented NLO-active functional motif, which can be useful in designing new IR NLO compounds with large SHG efficiency. In addition, the surfactant–thermal method provides a new general strategy for synthesizing new IR NLO materials.