A Promising Fluorooxoborate Framework with Flexibile Capability for Diverse Cations to Enhance the Second Harmonic Generation.

Fluorooxoborates as potential deep ultraviolet (DUV) nonlinear optical (NLO) materials have exhibited diverse structures and NLO properties with metal cationic changes. Herein, the general mechanisms of metal cations on band gaps and optical properties in a series of typical fluorooxoborates have been clarified. It reveals that the framework of the emblematic 18-membered ring oxyfluorides has the flexibility of being able to contain different cations spanning from alkali to d10 metals by investigating the stability of the artificial CdB5 O7 F3 structure. Besides, introducing d10 metal cations can enhance the second harmonic generation (3.1×KH2 PO4 (KDP), d36 =0.39 pm V-1 ) and also keep a DUV spectral transparency (Eg >6.2 eV). Thus, the d10 -containing fluorooxoborate exhibits a great potential to be a new DUV optical material for nonlinear light-matter interactions.