Structural Motif Cosubstitution Strategy for Designing Fluoroaluminoborate with the Sr2Be2B2O7-Type Double-Layered Structure

The cosubstitution strategy often was applied to design borate optical crystal materials. Revealingly, a fluoroaluminoborate Sr2Al2.18B5.82O13F2 with Sr2Be2B2O7 (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 Sr2Al2.18B5.82O13F2, a structural motif, the [Al2B6O14F4] unit, with edge-sharing [AlO4F2] octahedra was filled in interlamination of double-layer structure. The research indicates that Sr2Al2.18B5.82O13F2 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 [Al2B6O14F4] unit enlightens the synthesis and discovery of new layered structures in borates.