Ba5Ga2SiO4S6: a Phase-Matching Nonlinear Optical Oxychalcogenide Design via Structural Regulation Originated from Heteroanion Introduction.

ABSTRACT

Tailored structural regulation to obtain a new non-centrosymmetric (NCS) compound with excellent optical properties is highly desirable but remains a challenge for nonlinear optical (NLO) material design. In this work, centrosymmetric celsian-type BaGa2Si2O8 was selected as a template structure, and a novel NCS oxychalcogenide, namely, Ba5Ga2SiO4S6, was successfully designed via the introduction of heteroanions under high-temperature solid-state conditions. Ba5Ga2SiO4S6 adopts the monoclinic space group of Cc (no. 9) and is formed by charges balancing Ba2+ cations and discrete [Ga2SiO4S6] clusters made of corner-sharing [SiO4] and [GaOS3] tetrahedra. Notably, Ba5Ga2SiO4S6 exhibits the critical requirements as a potential UV NLO candidate, including a phase-matching second-harmonic generation intensity (∼1.0 × KDP), a beneficial laser-induced damage threshold (1.2 × KDP), a large birefringence (Δn = 0.10@546 nm), and a short UV absorption cutoff edge (ca. 0.26 µm). Furthermore, the theoretical calculation is implemented to provide a deeper analysis of the structure-activity relationship. The investigated example of structural regulation originated from heteroanion introduction in this study may offer a feasible strategy for high-performance NLO candidate design.