Synthesis, characterization and theoretical calculations of a new rare-earth fluoride with a DUV cutoff edge

A new mixed alkali metal and rare-earth metal fluoride, Rb 2 Sc 3 F 11 , was successfully synthesized using the high-temperature solution method. It is a rare example containing mixed ScF 7 and ScF 6 groups and crystallizes in the orthorhombic space group Imma (No. 74). Significantly, the optical characterization indicates that Rb 2 Sc 3 F 11 shows a short deep-ultraviolet (DUV) cutoff edge (<200 nm) due to the introduction of the rare-earth scandium and the fluorine with the large electronegativity. It also possesses a moderate birefringence (0.037@532 nm). First-principles calculations were also implemented for a better understanding of the relationship between structure with properties of Rb 2 Sc 3 F 11 .