Ba5Zn4(B3O6)2(B12O24): A Borate with Edge-Sharing [BO4] Tetrahedral Connection by Introducing Zn into β-BaB2O4

The edge-sharing connection mode of [BO4] tetrahedra has greatly enriched the structural chemistry of borates, which provides more options and possibilities for designing more materials with unique structures and excellent performance. A zinc borate Ba5Zn4(B3O6)2(B12O24) (BaZnBO) was synthesized via a high-temperature solid reaction. Its uniqueness lies in not only introducing Zn into the structure of β-BaB2O4 but also containing the unusual edge-sharing [BO4] tetrahedra. The functional building units are isolated [B3O6] and [B12O24] groups. The adjacent [B3O6] groups are linked to a layer in the ab plane and further stack along the [001] direction, while the [B12O24] groups are located in the middle of these layers, thus forming the “sandwich” structure. This work also analyzed the impact of introducing Zn into β-BaB2O4 on the structure of anions. In addition, BaZnBO also exhibits good thermal stability and excellent optical properties including the short cut-off edge (204 nm) and suitable birefringence (0.058@1064 nm).