Sr5ZnGa6S15: a new quaternary non-centrosymmetric semiconductor with a 3D framework structure displaying excellent nonlinear optical performance

Abstract

The search for new non-centrosymmetric (NCS) crystals with wide energy-gaps (E_g) and strong second-harmonic generation (SHG) responses has become one of the greatest challenges in the mid- and far-infrared (MFIR) nonlinear optical (NLO) field. In this work, a novel quaternary NCS material Sr₅ZnGa₆S₁₅ (SZGS), which contains a complex 3D anionic framework and possesses the optical properties required for the MFIR NLO applications, especially the good balance between wide E_g (3.15 eV) and large SHG response (d_ij = 1.2 × AgGaS₂), has been discovered for the first time. Moreover, the result of theoretical calculation further indicates that the 3D [ZnGa₆S₁₅]¹⁰⁻ framework makes definitive contributions to the NLO properties. All these studies demonstrate that SZGS is a promising NLO candidate in the MFIR region.