Materials Data on Mg3Al7(Si2O11)2 by Materials Project
Mg3Al7(Si2O11)2 crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. there are four inequivalent Mg sites. In the first Mg site, Mg is bonded to six O atoms to form distorted MgO6 octahedra that share corners with four SiO4 tetrahedra and edges with six AlO6 octahedra. There are a spread of Mg–O bond distances ranging from 2.01–2.19 Å. In the second Mg site, Mg is bonded to six O atoms to form distorted MgO6 octahedra that share corners with four SiO4 tetrahedra and edges with six AlO6 octahedra. There are a spread of Mg–O bond distances ranging from 2.03–2.23 Å. In the third Mg site, Mg is bonded to six O atoms to form distorted MgO6 octahedra that share a cornercorner with one MgO6 octahedra, corners with three SiO4 tetrahedra, edges with three AlO6 octahedra, and an edgeedge with one AlO4 tetrahedra. The corner-sharing octahedral tilt angles are 34°. There are a spread of Mg–O bond distances ranging from 2.06–2.23 Å. In the fourth Mg site, Mg is bonded in a 6-coordinate geometry to six O atoms. There are a spread of Mg–O bond distances ranging from 1.99–2.35 Å. There are five inequivalent Al sites. In the first Al site, Al is bonded to six O atoms to form AlO6 octahedra that share a cornercorner with one AlO4 tetrahedra, corners with three SiO4 tetrahedra, edges with two MgO6 octahedra, and edges with four AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.74–2.12 Å. In the second Al site, Al is bonded to six O atoms to form AlO6 octahedra that share corners with two equivalent AlO4 tetrahedra, corners with two SiO4 tetrahedra, an edgeedge with one MgO6 octahedra, and edges with four AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.85–2.03 Å. In the third Al site, Al is bonded to six O atoms to form AlO6 octahedra that share corners with two equivalent AlO6 octahedra, a cornercorner with one AlO4 tetrahedra, corners with three SiO4 tetrahedra, edges with two MgO6 octahedra, and edges with four AlO6 octahedra. The corner-sharing octahedra tilt angles range from 39–44°. There are a spread of Al–O bond distances ranging from 1.81–2.04 Å. In the fourth Al site, Al is bonded to six O atoms to form distorted AlO6 octahedra that share corners with two equivalent AlO6 octahedra, a cornercorner with one AlO4 tetrahedra, corners with three SiO4 tetrahedra, an edgeedge with one MgO6 octahedra, and edges with three AlO6 octahedra. The corner-sharing octahedra tilt angles range from 41–44°. There are a spread of Al–O bond distances ranging from 1.82–2.26 Å. In the fifth Al site, Al is bonded to four O atoms to form AlO4 tetrahedra that share corners with seven AlO6 octahedra, a cornercorner with one SiO4 tetrahedra, and an edgeedge with one MgO6 octahedra. The corner-sharing octahedra tilt angles range from 18–65°. There are a spread of Al–O bond distances ranging from 1.69–1.80 Å. There are five inequivalent Si sites. In the first Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share a cornercorner with one MgO6 octahedra, corners with three AlO6 octahedra, and a cornercorner with one SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 45–55°. There are a spread of Si–O bond distances ranging from 1.62–1.66 Å. In the second Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with three MgO6 octahedra, corners with three AlO6 octahedra, and a cornercorner with one SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 44–57°. There are a spread of Si–O bond distances ranging from 1.63–1.67 Å. In the third Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with four MgO6 octahedra, corners with four equivalent AlO6 octahedra, and corners with two equivalent AlO4 tetrahedra. The corner-sharing octahedra tilt angles range from 41–60°. There is two shorter (1.60 Å) and two longer (1.67 Å) Si–O bond length. In the fourth Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with two equivalent MgO6 octahedra, corners with four equivalent AlO6 octahedra, and corners with two equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 56–61°. There is two shorter (1.63 Å) and two longer (1.64 Å) Si–O bond length. In the fifth Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with seven AlO6 octahedra and a cornercorner with one SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 11–61°. There are a spread of Si–O bond distances ranging from 1.59–1.71 Å. There are twenty inequivalent O sites. In the first O site, O is bonded in a distorted trigonal planar geometry to one Mg, one Al, and one Si atom. In the second O site, O is bonded in a 3-coordinate geometry to one Mg, one Al, and one Si atom. In the third O site, O is bonded in a distorted T-shaped geometry to one Mg and two Al atoms. In the fourth O site, O is bonded in a distorted T-shaped geometry to one Mg, one Al, and one Si atom. In the fifth O site, O is bonded in a bent 150 degrees geometry to two equivalent Mg atoms. In the sixth O site, O is bonded in a bent 150 degrees geometry to two equivalent Mg atoms. In the seventh O site, O is bonded to one Mg and three Al atoms to form distorted OMgAl3 tetrahedra that share corners with three OMgAl3 tetrahedra, corners with five OMgAl3 trigonal pyramids, and edges with two equivalent OMgAl2Si trigonal pyramids. In the eighth O site, O is bonded to one Mg and three Al atoms to form distorted OMgAl3 trigonal pyramids that share corners with three OMgAl3 tetrahedra, corners with three OMgAl3 trigonal pyramids, edges with two equivalent OAl4 tetrahedra, and edges with two equivalent OMgAl2Si trigonal pyramids. In the ninth O site, O is bonded to one Mg, two equivalent Al, and one Si atom to form distorted OMgAl2Si trigonal pyramids that share corners with two equivalent OAl4 tetrahedra, corners with four OMgAl3 trigonal pyramids, edges with two equivalent OMgAl3 tetrahedra, and an edgeedge with one OMgAl2Si trigonal pyramid. In the tenth O site, O is bonded to one Mg, two equivalent Al, and one Si atom to form distorted OMgAl2Si trigonal pyramids that share corners with four OMgAl3 tetrahedra, corners with two equivalent OMgAl2Si trigonal pyramids, and edges with three OMgAl2Si trigonal pyramids. In the eleventh O site, O is bonded to one Mg and three Al atoms to form corner-sharing OMgAl3 trigonal pyramids. In the twelfth O site, O is bonded to one Mg and three Al atoms to form OMgAl3 tetrahedra that share corners with three OMgAl3 trigonal pyramids and edges with two equivalent OAl4 tetrahedra. In the thirteenth O site, O is bonded in a distorted trigonal planar geometry to one Mg, one Al, and one Si atom. In the fourteenth O site, O is bonded in a distorted trigonal planar geometry to one Mg and two Si atoms. In the fifteenth O site, O is bonded in a bent 150 degrees geometry to two equivalent Si atoms. In the sixteenth O site, O is bonded in a bent 150 degrees geometry to two equivalent Si atoms. In the seventeenth O site, O is bonded in a distorted rectangular see-saw-like geometry to three Al and one Si atom. In the eighteenth O site, O is bonded to four Al atoms to form distorted OAl4 tetrahedra that share corners with three OMgAl3 tetrahedra, corners with three OMgAl2Si trigonal pyramids, an edgeedge with one OMgAl3 tetrahedra, and an edgeedge with one OMgAl3 trigonal pyramid. In the nineteenth O site, O is bonded in a distorted trigonal planar geometry to one Mg, one Al, and one Si atom. In the twentieth O site, O is bonded in a distorted trigonal planar geometry to one Mg, one Al, and one Si atom.