Materials Data on Mg5Al7O16 by Materials Project

Abstract

Mg5Al7O16 is Spinel-like structured and crystallizes in the monoclinic P2/m space group. The structure is three-dimensional. there are three inequivalent Mg sites. In the first Mg site, Mg is bonded to six O atoms to form MgO6 octahedra that share corners with six MgO4 tetrahedra and edges with six AlO6 octahedra. There are four shorter (2.07 Å) and two longer (2.08 Å) Mg–O bond lengths. In the second Mg site, Mg is bonded to four O atoms to form MgO4 tetrahedra that share a cornercorner with one MgO6 octahedra and corners with eleven AlO6 octahedra. The corner-sharing octahedra tilt angles range from 57–65°. There is two shorter (1.96 Å) and two longer (1.97 Å) Mg–O bond length. In the third Mg site, Mg is bonded to four O atoms to form MgO4 tetrahedra that share corners with two equivalent MgO6 octahedra and corners with ten AlO6 octahedra. The corner-sharing octahedra tilt angles range from 55–65°. There are a spread of Mg–O bond distances ranging from 1.96–2.00 Å. There are four inequivalent Al sites. In the first Al site, Al is bonded to six O atoms to form AlO6 octahedra that share corners with six MgO4 tetrahedra and edges with six AlO6 octahedra. There is two shorter (1.91 Å) and four longer (1.94 Å) Al–O bond length. In the second Al site, Al is bonded to six O atoms to form AlO6 octahedra that share corners with six MgO4 tetrahedra, edges with two equivalent MgO6 octahedra, and edges with four equivalent AlO6 octahedra. There is four shorter (1.92 Å) and two longer (1.96 Å) Al–O bond length. In the third Al site, Al is bonded to six O atoms to form AlO6 octahedra that share corners with six MgO4 tetrahedra and edges with six AlO6 octahedra. There is four shorter (1.94 Å) and two longer (1.95 Å) Al–O bond length. In the fourth Al site, Al is bonded to six O atoms to form AlO6 octahedra that share corners with six MgO4 tetrahedra, an edgeedge with one MgO6 octahedra, and edges with five AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.91–1.96 Å. There are six inequivalent O sites. In the first O site, O is bonded to one Mg and three Al atoms to form a mixture of distorted corner and edge-sharing OMgAl3 trigonal pyramids. In the second O site, O is bonded to one Mg and three Al atoms to form distorted OMgAl3 trigonal pyramids that share corners with two equivalent OMgAl3 tetrahedra, corners with eight OMgAl3 trigonal pyramids, and an edgeedge with one OMg2Al2 trigonal pyramid. In the third O site, O is bonded to one Mg and three Al atoms to form a mixture of distorted corner and edge-sharing OMgAl3 tetrahedra. In the fourth O site, O is bonded to two Mg and two equivalent Al atoms to form a mixture of distorted corner and edge-sharing OMg2Al2 trigonal pyramids. In the fifth O site, O is bonded to one Mg and three Al atoms to form a mixture of distorted corner and edge-sharing OMgAl3 trigonal pyramids. In the sixth O site, O is bonded in a rectangular see-saw-like geometry to two Mg and two Al atoms.