Ba 10 In 2 Mn 11 Si 3 O 12 S 18 : First Hexanary Oxychalcogenide Containing an Infrequent Three-Dimensional Noncentrosysmmetric Framework.

Noncentrosymmetric (NCS) oxychalcogenides have attracted great attention in recent years due to their immense potential as candidates for IR nonlinear-optical (NLO) applications. Despite notable advancements in this field, the discovery of oxychalcogenides with three-dimensional (3D) framework structures remains a formidable challenge. In this study, we report the discovery of the first hexanary oxychalcogenide, Ba 10 In 2 Mn 11 Si 3 O 12 S 18 , exhibiting second-order NLO activity, using a high-temperature solid-phase method. This compound showcases a novel structure type, featuring an uncommon NCS 3D [In 2 Mn 11 Si 3 O 12 S 18 ] 20- framework formed by vertex-sharing [(Mn/In)S 6 ] octahedra, [(Mn/In)OS 3 ] tetrahedra, and [SiO 4 ] tetrahedra, with charge-balanced Ba 2+ cations occupying the channels. Our study serves as a source of inspiration for researchers to further investigate the synthesis of novel NLO-active oxychalcogenides with 3D frameworks.