Synthesis and crystal structure of the gallium-containing montebrasite analogue LiGa(OH)PO4

Gallium lithium hydroxyphosphate LiGa(OH)PO4 was prepared under mild hydrothermal conditions (T = 160°C, τ = 48 h) and characterized (IR spectroscopy, chemical and thermal analysis). LiGa(OH)PO4 was found to be structurally similar to the ambligonite family phases. The crystal structure was refined by the Rietveld method (space group $$P\bar 1$$ , Z = 2): a = 5.0853(1) Å, b = 5.2973(1) Å, c = 7.3006(1) Å, α = 67.830(1)°, β = 67.839(1)°, γ = 82.027(1)°, R p = 0.0519, R wp = 0.0765. A zero SHG signal confirmed a centrosymmetric structure of the compound. The structure is represented by a mixed {Ga(OH)[PO4]} 3∞ − framework composed of the PO4 tetrahedra and GaO4(OH)2 octahedra. The framework contains hexagonal channels running in the [100] and [010] directions. The basic element of the framework is a linear chain of GaO4(OH)2 octahedra sharing trans OH vertices. The Li+ ions reside in the framework voids.