Neutron powder diffraction studies of LiMn2−yAlyO4 synthesized by the emulsion drying method

The aluminum-doped spinel-type lithium manganese oxides, LiMn2−yAlyO4, have been successfully synthesized through the emulsion drying method, and their crystal structures were studied by neutron powder diffraction. Rietveld refinements of their neutron diffraction data revealed that Al was substituted selectively for Mn at the 16d site and that Li occupied only the 8a site. Thus, the Al-doped compound can be expressed as [Li]8a[Mn2−yAly]16d[O4]32e (y=0–0.452). The lattice constant a decreased linearly with increasing the occupation factor g(Al). The length of (Mn, Al)O bonds in (Mn, Al)O6 octahedra changed in a manner expected from average ionic radii for Mn1−g(Al)Alg(Al).