NaSr₃Be₃B₃O₉F₄: A Promising Deep‐Ultraviolet Nonlinear Optical Material Resulting from the Cooperative Alignment of the [Be₃B₃O₁₂F]¹⁰⁻ Anionic Group

Structure matters: Owing to the structure and arrangement of the [Be3B3O12F]10− group (see picture, left, Be blue, B olive, F green, O red), the mixed-cation fluorine beryllium borate NaSr3Be3B3O9F4 (right) exhibits a large second harmonic generation effect and a short UV absorption edge. Its crystals show no layering tendency, making it promising for applications in deep-UV nonlinear optics.