CsMgGa5S9: a diamond-like network made of mixed tetrahedral units for excellent nonlinear optical properties

CsMgGa₅S₉ features a diamond-like framework with uniformly stacked mixed tetrahedral units and embedded Cs⁺ ions. It exhibits a favorable second-harmonic generation response (0.5 × AgGaS₂@1910 nm) and a large bandgap (3.12 eV) that yield a high laser-induced damage threshold (8.0 × AgGaS₂@1064 nm), making it an excellent nonlinear optical material.