DOE OSTI2020
LaMgAl11O19 is beta indium sulfide-derived structured and crystallizes in the orthorhombic Cmc2_1 space group. The structure is three-dimensional. Mg2+ is bonded to four O2- atoms to form MgO4 tetrahedra that share corners with twelve AlO6 octahedra. The corner-sharing octahedra tilt angles range from 57–60°. There is three shorter (1.93 Å) and one longer (1.98 Å) Mg–O bond length. La3+ is bonded to twelve O2- atoms to form LaO12 cuboctahedra that share corners with six equivalent LaO12 cuboctahedra, edges with six AlO6 octahedra, edges with three equivalent AlO4 trigonal pyramids, and faces with six AlO6 octahedra. There are a spread of La–O bond distances ranging from 2.67–2.83 Å. There are nine inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with three equivalent MgO4 tetrahedra, corners with three equivalent AlO4 tetrahedra, and edges with six AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.87–1.95 Å. In the second Al3+ site, Al3+ is bonded to four O2- atoms to form distorted AlO4 trigonal pyramids that share corners with nine AlO6 octahedra and edges with three equivalent LaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 34–58°. There is three shorter (1.79 Å) and one longer (1.86 Å) Al–O bond length. In the third Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with two equivalent AlO6 octahedra, a cornercorner with one AlO4 tetrahedra, corners with two equivalent MgO4 tetrahedra, a cornercorner with one AlO4 trigonal pyramid, an edgeedge with one LaO12 cuboctahedra, and edges with five AlO6 octahedra. The corner-sharing octahedral tilt angles are 54°. There are a spread of Al–O bond distances ranging from 1.88–1.99 Å. In the fourth Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with two equivalent AlO6 octahedra, a cornercorner with one AlO4 tetrahedra, corners with two equivalent MgO4 tetrahedra, a cornercorner with one AlO4 trigonal pyramid, an edgeedge with one LaO12 cuboctahedra, and edges with five AlO6 octahedra. The corner-sharing octahedral tilt angles are 54°. There are a spread of Al–O bond distances ranging from 1.88–1.99 Å. In the fifth Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with two equivalent AlO6 octahedra, a cornercorner with one MgO4 tetrahedra, corners with two equivalent AlO4 tetrahedra, an edgeedge with one LaO12 cuboctahedra, and edges with five AlO6 octahedra. The corner-sharing octahedral tilt angles are 52°. There are a spread of Al–O bond distances ranging from 1.85–2.04 Å. In the sixth Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with two equivalent AlO6 octahedra, a cornercorner with one MgO4 tetrahedra, corners with two equivalent AlO4 tetrahedra, an edgeedge with one LaO12 cuboctahedra, and edges with five AlO6 octahedra. The corner-sharing octahedra tilt angles range from 52–53°. There are a spread of Al–O bond distances ranging from 1.85–2.04 Å. In the seventh Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with six AlO6 octahedra, corners with three equivalent AlO4 trigonal pyramids, faces with three equivalent LaO12 cuboctahedra, and a faceface with one AlO6 octahedra. The corner-sharing octahedral tilt angles are 54°. There is three shorter (1.89 Å) and three longer (2.01 Å) Al–O bond length. In the eighth Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with six AlO6 octahedra, corners with three equivalent AlO4 trigonal pyramids, faces with three equivalent LaO12 cuboctahedra, and a faceface with one AlO6 octahedra. The corner-sharing octahedra tilt angles range from 52–53°. There are a spread of Al–O bond distances ranging from 1.87–2.01 Å. In the ninth Al3+ site, Al3+ is bonded to four O2- atoms to form corner-sharing AlO4 tetrahedra. The corner-sharing octahedra tilt angles range from 55–59°. There is three shorter (1.82 Å) and one longer (1.83 Å) Al–O bond length. There are thirteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent La3+ and three Al3+ atoms. In the second O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent La3+ and three Al3+ atoms. In the third O2- site, O2- is bonded to four Al3+ atoms to form distorted edge-sharing OAl4 trigonal pyramids. In the fourth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to three Al3+ atoms. In the fifth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to four Al3+ atoms. In the sixth O2- site, O2- is bonded to one Mg2+ and three Al3+ atoms to form distorted corner-sharing OMgAl3 trigonal pyramids. In the seventh O2- site, O2- is bonded to one Mg2+ and three Al3+ atoms to form distorted OMgAl3 trigonal pyramids that share corners with three OMgAl3 trigonal pyramids and edges with three OAl4 trigonal pyramids. In the eighth O2- site, O2- is bonded to one Mg2+ and three Al3+ atoms to form a mixture of distorted edge and corner-sharing OMgAl3 trigonal pyramids. In the ninth O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Al3+ atoms. In the tenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Al3+ atoms. In the eleventh O2- site, O2- is bonded in a 3-coordinate geometry to one La3+ and three Al3+ atoms. In the twelfth O2- site, O2- is bonded in a 3-coordinate geometry to one La3+ and three Al3+ atoms. In the thirteenth O2- site, O2- is bonded in a 3-coordinate geometry to one La3+ and three Al3+ atoms.