Two Ultraviolet Optical Crystals K 6 B 12 O 19 F 4 and K 12 B 28 O 48 : The Effects of Metal Cations Size and the F Ions on the Structure

Borates and fluorooxoborates are advanced optical materials with great potential applications in the ultraviolet (UV) and deep ultraviolet (DUV) regions. Herein, two new UV optical crystals K B O F and K B O were synthesized. Among them, K B O F has a rare disorder of BO and BO units, which is the first time this disordered type has been found in fluorooxoborates. In this paper, the properties of K B O F and K B O were tested and calculated, and their crystal structures and structural evolution were carefully analyzed. In addition, the effects of metal cations size and F ions on the crystal structure were analyzed. This research enriches the structural chemistry of borates and fluorooxoborates, and provides experience for the design of new UV optical crystals.