M 6 PS 5 X (M = Ag, Cu; X = Cl, Br) chalcohalides exhibiting strong nonlinear optical responses and high laser damage resistances.

A series of M ₆ PS ₅ X (M = Ag, Cu; X = Cl, Br) nonlinear optical (NLO) chalcohalides with special MS ₃ X ligands have been synthesized in this work. Their critical optical performances were systematically measured and the research results show that all of them exhibit strong NLO responses (2.0-2.7 × commercial AgGaS ₂ ) and high laser-damage thresholds (1.7-2.3 × AgGaS ₂ ), indicating their potential application as good NLO candidates. Furthermore, first-principles calculations were used to study their inherent structure-property relationships and chalcohalides can be expected to be optimal systems for the exploration of new promising IR NLO crystals.