Eu5ZnGa6S15, Eu5Zn3Ga2Sn2S15, and Pb5HgGa6S15: Crystal Chemistry and Nonlinear Optical Properties

Abstract

The strategy of structural transformation from centrosymmetric (CS) to noncentrosymmetric (NCS) has been proved to be highly effective for exploring new nonlinear optical (NLO) materials. By introducing other tetra-coordinated cations Zn, Hg, and Sn into MGa2S4 (M = Pb, Eu) (0), a series of new multinary metal sulfides Eu5ZnGa6S15 (1), Eu5Zn3Ga2Sn2S15 (2), and Pb5HgGa6S15 (3) were obtained, which realize the CS–NCS structural transformation. 1–3 crystallize with the orthorhombic polar Ama2 space group and feature hybrid T2-supertetrahedral structure. They exhibit phase matchable NLO responses of 0.24–1.58 × AgGaS2, moderate band gaps of 2.08–2.28 eV, improved laser-induced damage thresholds of 1.37–1.63 × AgGaS2, and appropriate birefringence of 0.057–0.063. The outstanding NLO properties of 3 can be attributed to the Hg/Ga-mixed T2-supertetrahedral clusters, which is verified by the theoretical calculations.