From oxides to oxysulfides: the mixed-anion GeS3O unit induces huge improvement in the nonlinear optical effect and optical anisotropy for potential nonlinear optical materials

Oxysulfides combining intrinsic performance advantages between sulfides (strong NLO response) and oxides (wide optical bandgap) are proposed as potential infrared (IR) NLO materials. Theoretical calculation shows that the mixed-anion GeS3O tetrahedron has a stronger polarizability anisotropy and hyperpolarizability than that of the typical GeO4 unit. Based on this, two Sr2MGe2S6O (M = Zn, Cd) oxysulfides with the GeS3O unit show dozens of times improvement in critical birefringence and the NLO effect compared with those of isostructural Sr2ZnGe2O7. Moreover, structure-property study further verifies that the mixed-anion GeS3O ligand is a useful NLO-active unit and can offer great influence over the NLO origin. This research result also gives us a feasible design strategy and research system to explore new IR NLO candidates.

Automated summary

This article proposes oxysulfides as potential infrared (IR) nonlinear optical (NLO) materials that combine the performance advantages of sulfides and oxides. The study shows that GeS3O units in oxysulfides exhibit stronger polarizability anisotropy and hyperpolarizability compared to typical GeO4 units. The research also demonstrates that the mixed-anion GeS3O ligand is a useful NLO-active unit that greatly influences the NLO origin. This provides a feasible design strategy and research system for exploring new IR NLO candidates.