Two fluorophosphates exhibit a S = 2 uniform chain structure formed by MnO2F4 octahedra with corner-sharing F atoms along the b-axis.
By incorporating multiple alkali and alkaline-earth metal elements, we have successfully synthesized and report the first tri-alkali/alkaline-earth metal fluorophosphate KBaSr(PO2F2)(PO3F)2 as a promising deep-ultraviolet birefringent crystal.
(CN4H7)2PO3F·H2O and (C4N4H11)2PO3F·H2O exhibit large birefringence values of 0.116 and 0.165 at 546 nm, surpassing those of most previously reported monofluorophosphates/difluorophosphates.
We report the concept of anisotropic structure building units encompassing diverse chemical bonds (ABUCB), which play a crucial role in optimizing the overall second-order nonlinear optical performance of both DUV/UV and IR NLO materials.
Here, the polar covalent group (PO3NH3)− is identified as a novel deep-ultraviolet (DUV) NLO-active unit. Its ordered arrangement in NaPO3NH3 makes this compound exhibiting the largest birefringence among DUV non-π-conjugated phosphate systems.