Structure of LiGa5O8

Lithiumpentagalliumoctaoxide, LiGa5O8, crystallizes as an inverse spinel with gallium both in tetrahedral and octahedral sites, while lithium is in an octahedral environment. The oxygen tetrahedron surrounding gallium is nearly perfect with O-Ga-O bond angles of 109.4(1) and 109.6(1)degrees. Ideally, the spinel chains of edge-sharing octahedra have every fourth gallium octahedron occupied by lithium. The actual chains are disordered with 17.0(2)% of the gallium positions occupied by lithium and 53.9(1)% of the lithium positions occupied by gallium. Crystals were grown from a PbO-B2O3 flux with a cooling rate of 2.3 K h(-1) from 1573 to 773 K, yielding clear colourless octahedral crystals with edges of up to 5 mm. LiGa5O8 crystallizes in the cubic space group P4(3)32 (or P4(1)32) with a = 8.2023(6) Angstrom and four formula units per cell. The least-squares refinement converged at R(w) = 0.043 for 544 reflections with I > 3 sigma(I).