Beschreibung:
<jats:title>Abstract</jats:title><jats:p>The development of high‐power solid‐state lasers is in urgent need of infrared (IR) nonlinear optical (NLO) materials with wide band gaps and high laser‐induced damage thresholds (LIDTs). Herein, a new compressed chalcopyrite‐like IR NLO crystal (Na<jats:sub>0.74</jats:sub>Ag<jats:sub>1.26</jats:sub>)BaSnS<jats:sub>4</jats:sub> was successfully synthesized using a facile high‐temperature solid‐state method. Its structure can be considered as a variant of chalcopyrite AgGaS<jats:sub>2</jats:sub> (AGS)‐type ones. It features a three‐dimensional framework constructed by corner‐sharing {[(Na/Ag)S<jats:sub>4</jats:sub>]<jats:sup>7−</jats:sup>}<jats:sub>∞</jats:sub> layers and isolated SnS<jats:sub>4</jats:sub> tetrahedra with negative cavities occupied by counter ion Ba<jats:sup>2+</jats:sup>. (Na<jats:sub>0.74</jats:sub>Ag<jats:sub>1.26</jats:sub>)BaSnS<jats:sub>4</jats:sub> exhibits phase‐matchable moderate SHG response (0.31 × AGS), wide band gap (3.70 eV), and high LIDT (6.44 × AGS). Theoretical calculations reveal that the NLO response of (Na<jats:sub>0.74</jats:sub>Ag<jats:sub>1.26</jats:sub>)BaSnS<jats:sub>4</jats:sub> is mainly originated from the synergetic effects of AgS<jats:sub>4</jats:sub> and SnS<jats:sub>4</jats:sub> tetrahedra, and the inclusion of alkaline and alkaline earth metals is responsible for the wide band gap and high LIDT. Moreover, the discovery of this chalcopyrite‐like compound will provide a feasible design strategy for the exploration of new promising IR NLO materials.</jats:p>