Hydrothermal synthesis and structure determination of the first three-dimensional oxyfluorinated gallium phosphate incorporating lithium

Abstract

Abstract LiGa3F3(OH)(H2O)2(PO4)2 was synthesised hydrothermally (453 K, 36 h, autogeneous pressure) from the mixture with molar composition 0.5 Ga2O3 : 0.5 P2O5 : 3 HF : 0.2 Li2O : 80 H2O. Its three-dimensional structure was solved, at 298 K, by single-crystal X-ray diffraction in the monoclinic space group P21/c (No. 14) with lattice parameters a=8.6885(4) A, b=8.2442(4) A, c=7.1303(4) A, β=104.351(2) A, V=494.80(4) A3, Z=2. Its structure consists of infinite double sheets, made from corner shared GaO3F{F2–x(OH)x} octahedra (x=0, 1 or 2) and PO4 tetrahedra of laueite-type chains, which are linked by GaO2F2(H2O)2 octahedra to generate the framework encapsulating lithium cations. The OH/F substitution is discussed from solid state NMR results.