Ba₂Ga₂F₆(IO₃)(PO₄): the first fluoride-containing iodate-phosphate with a 1D [Ga₂F₆(IO₃)(PO₄)]^4- helix chain

Herein, the first F-containing iodate-phosphate, namely Ba₂Ga₂F₆(IO₃)(PO₄), was prepared via a hydrothermal reaction, in which HPF₆ (70 wt% solution in water) was used as the source of both fluoride and phosphate anions for the first time. Ba₂Ga₂F₆(IO₃)(PO₄) features an unprecedented 1D [Ga₂F₆(IO₃)(PO₄)]^4- helix chain, composed of a 1D Ga(1)(IO₃)O₄F chain via the bridging of 0D Ga(2)(PO₄)F₅. The UV-Vis spectrum shows that Ba₂Ga₂F₆(IO₃)(PO₄) has a wide bandgap with a short-UV absorption edge (4.35 eV; 253 nm). Birefringence measurement under a polarizing microscope shows that Ba₂Ga₂F₆(IO₃)(PO₄) displays a moderate birefringence of 0.072@550 nm, which is consistent with the value (0.070@550 nm) obtained by DFT calculations, indicating that Ba₂Ga₂F₆(IO₃)(PO₄) has potential applications as a short-UV birefringent material. This study highlights the crucial role played by the incorporation of specific functional groups into compounds, shedding light on their contribution to promising inorganic functional materials.