KF·B(OH)3: a KBBF-type material with large birefringence and remarkable deep-ultraviolet transparency

A new KBBF-type crystal, KF·B(OH) 3 , exhibits a good balance between birefringence (0.114 @1064 nm) and bandgap (7.63 eV) owing to the designed [F·B(OH) 3 ] − layers.