“…During past few years, several borate halide NLO materials with excellent second harmonic generation (SHG) properties have been reported: KBe 2 BO 3 F 2 (KBBF), Ba 4 B 11 O 20 F, Rb 3 Al 3 B 3 O 10 F, M 3 M′ 3 Li 2 Al 4 B 6 O 20 F (M=K + , Rb + ; M′=Sr 2+ , Ba 2+ ), Ca 5 (BO 3 ) 3 F, BaCaBO 3 F, M 3 B 6 O 11 F 2 , Pb 2 Ba 3 (BO 3 ) 3 Cl, K 3 B 6 O 10 Cl, Pb 2 B 5 O 9 I . Recently, some fluoroborates, such as LiB 6 O 9 F, NH 4 B 4 O 6 F, CsB 4 O 6 F, and AB 4 O 6 F (A=K, Rb, and Cs) show promise as deep‐UV NLO materials.…”