STRUCTURE OF LIGA5O8

Lithiumpentagalliumoctaoxide, LiGa5O8, crystallizes as an inverse spin el with gallium both in tetrahedral and octahedral sites, while lithiu m 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 chain s are disordered with 17.0(2)% of the gallium positions occupied by li thium and 53.9(1)% of the lithium positions occupied by gallium. Cryst als 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 wit h edges of up to 5 mm. LiGa5O8 crystallizes in the cubic space group P 4(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).