BaB 2 O 3 F 2 : A Barium Fluorooxoborate with a Unique [B 2 O 3 F] − Layer and Short Cutoff Edge

Substitution of oxygen by fluorine in the borate group offers a materials platform from which intriguing structure and functionality may arise. Herein, we report a new fluorooxoborate, BaB2 O3 F2 , synthesized by introducing the F atoms into the BaO-B2 O3 system. BaB2 O3 F2 exhibits a unique oxyfluoride layer 2∞ [B2 O3 F]- and a deep-ultraviolet cutoff edge below 180 nm. The effect of the introduction of F atoms on the structure and optical property of the borate group has been investigated; this should be useful to further expand borate chemistry and materials.