At a 2 : 1 BO 3 : BO 3 F ratio, CaB 3 O 5 F features a 1D chain (SHG d 23 =1.12 V) pm V −1 and CaB 6 O 9 F 2 forms a 2D layer (Δ n = 0.101). This fills a structural gap and advances the design of DUV NLO fluorooxoborates.
Qi et al. (Thu,) studied this question.