Structural Motif Cosubstitution Strategy for Designing Fluoroaluminoborate with the Sr 2 Be 2 B 2 O 7 -Type Double-Layered Structure.

The cosubstitution strategy often was applied to design borate optical crystal materials. Revealingly, a fluoroaluminoborate Sr 2 Al 2.18 B 5.82 O 13 F 2 with Sr 2 Be 2 B 2 O 7 (SBBO) double-layered like configuration has been rationally designed and successfully synthesized based on structural motif cosubstitution strategy via the high-temperature solution method. In Sr 2 Al 2.18 B 5.82 O 13 F 2 , a structural motif, the [Al 2 B 6 O 14 F 4 ] unit, with edge-sharing [AlO 4 F 2 ] octahedra was filled in interlamination of double-layer structure. The research indicates that Sr 2 Al 2.18 B 5.82 O 13 F 2 features a short ultraviolet cutoff edge (<200 nm) and moderate birefringence (∼0.058 @ 1064 nm). As the first reported linker in the interlamination of double-layer structures, the [Al 2 B 6 O 14 F 4 ] unit enlightens the synthesis and discovery of new layered structures in borates.