Two New Ferroborates with Three‐Dimensional Framework and Wide Transmittance Window

Two ferroborates Li 5 MSrFeB 12 O 24 (M = Mg, Zn) crystallized in trigonal R 3 space group, were obtained by high temperature solid state reaction. Centimeter‐level Li 5 MgSrFeB 12 O 24 single crystals were grown from high temperature solution using Li 2 B 4 O 7 as a self‐flux. In their structures, [FeO 6 ] octahedra connect with [B 2 O 6 ] chains by corner‐sharing O atoms forming the three‐dimensional [FeB 12 O 24 ] framework. The family of ferroborates(III) was summarized and the structural comparison with Ba 2 MgB 6 O 12 based on cation cosubstitution was also discussed to better understand the crystal structures of Li 5 MSrFeB 12 O 24 (M = Mg, Zn). The transmittance spectrum of a Li 5 MgSrFeB 12 O 24 crystal was measured to detect its transmittance window. In addition, thermal behaviors, other optical and magnetic characteristics of Li 5 MSrFeB 12 O 24 (M = Mg, Zn) were discussed as well.