Materials Data on Li2Mn4O9 by Materials Project
Li2Mn4O9 is Ilmenite-like structured and crystallizes in the trigonal P-3c1 space group. The structure is three-dimensional. Li1+ is bonded to six O2- atoms to form LiO6 octahedra that share corners with nine MnO6 octahedra, edges with three equivalent MnO6 octahedra, and a faceface with one LiO6 octahedra. The corner-sharing octahedra tilt angles range from 48–61°. There are three shorter (2.01 Å) and three longer (2.14 Å) Li–O bond lengths. There are two inequivalent Mn4+ sites. In the first Mn4+ site, Mn4+ is bonded to six equivalent O2- atoms to form MnO6 octahedra that share corners with three equivalent MnO6 octahedra, corners with six equivalent LiO6 octahedra, edges with three equivalent MnO6 octahedra, and a faceface with one MnO6 octahedra. The corner-sharing octahedra tilt angles range from 45–61°. There is three shorter (1.92 Å) and three longer (1.95 Å) Mn–O bond length. In the second Mn4+ site, Mn4+ is bonded to six O2- atoms to form MnO6 octahedra that share corners with three equivalent LiO6 octahedra, corners with six MnO6 octahedra, edges with three equivalent LiO6 octahedra, and a faceface with one MnO6 octahedra. The corner-sharing octahedra tilt angles range from 45–53°. There is three shorter (1.88 Å) and three longer (2.04 Å) Mn–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to two equivalent Li1+ and two equivalent Mn4+ atoms to form a mixture of distorted edge and corner-sharing OLi2Mn2 trigonal pyramids. In the second O2- site, O2- is bonded in a distorted see-saw-like geometry to one Li1+ and three Mn4+ atoms.