Non-centrosymmetric sulfides A2Ba6MnSn4S16 (A = Li, Ag): syntheses, structures and properties.

Two new penternary compounds, with the chemical formula of A2Ba6MnSn4S16 (A = Li (1), Ag (2)), have been successfully designed and prepared. They are isostructural and feature the same non-centrosymmetric three-dimensional (3D) framework, which comprises SnS4 tetrahedra and distorted (A/Mn)S4 tetrahedra. They both show strong second-harmonic generation (SHG) responses at 2.05 μm laser radiation of 5.1 and 2.7 × AgGaS2, respectively, at a particle size of 30-40 μm. Meanwhile, they exhibit wide band gaps of 2.88 and 2.76 eV, implying that they avoid two-photon absorption and low laser-induced damage thresholds (LIDTs). Furthermore, with Mn2+ cations modulating disordered sites, the two title compounds also possess paramagnetism. Based on the relationship between the structures and properties of the title compounds and related materials, it can be concluded that new materials with attractive properties can be designed and produced by modulating disordered sites with rational cations.