DOI: 10.17188/1263260
title: Materials Data on MgAl2O4 by Materials Project

description: MgAl2O4 is Spinel-like structured and crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are eight inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to four O2- atoms to form MgO4 tetrahedra that share corners with three equivalent MgO6 octahedra and corners with nine AlO6 octahedra. The corner-sharing octahedra tilt angles range from 56–62°. There is three shorter (1.93 Å) and one longer (2.00 Å) Mg–O bond length. In the second Mg2+ site, Mg2+ is bonded to four O2- atoms to form MgO4 tetrahedra that share corners with three equivalent MgO6 octahedra and corners with nine AlO6 octahedra. The corner-sharing octahedra tilt angles range from 57–63°. There is three shorter (1.94 Å) and one longer (1.98 Å) Mg–O bond length. In the third Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 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 Mg–O bond distances ranging from 2.03–2.08 Å. In the fourth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent AlO4 tetrahedra, corners with four MgO4 tetrahedra, and edges with six AlO6 octahedra. There are a spread of Mg–O bond distances ranging from 2.01–2.09 Å. In the fifth Mg2+ site, Mg2+ is bonded to four O2- 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 are a spread of Mg–O bond distances ranging from 1.97–1.99 Å. In the sixth Mg2+ site, Mg2+ is bonded to four O2- 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 56–62°. There are a spread of Mg–O bond distances ranging from 1.97–1.99 Å. In the seventh Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with three equivalent MgO4 tetrahedra, corners with three equivalent AlO4 tetrahedra, and edges with six AlO6 octahedra. There are three shorter (2.02 Å) and three longer (2.09 Å) Mg–O bond lengths. In the eighth Mg2+ site, Mg2+ is bonded to four O2- 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 56–63°. There are a spread of Mg–O bond distances ranging from 1.94–2.00 Å. There are twelve inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with three MgO4 tetrahedra, corners with three AlO4 tetrahedra, edges with two MgO6 octahedra, and edges with four equivalent AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.88–2.03 Å. In the second Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with three MgO4 tetrahedra, corners with three AlO4 tetrahedra, edges with two MgO6 octahedra, and edges with four AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.88–2.03 Å. In the third Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with two AlO4 tetrahedra, corners with four 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 1.86–2.06 Å. In the fourth Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with two AlO4 tetrahedra, corners with four 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 1.86–2.05 Å. In the fifth Al3+ site, Al3+ is bonded to four O2- atoms to form AlO4 tetrahedra that share corners with two equivalent MgO6 octahedra and corners with ten AlO6 octahedra. The corner-sharing octahedra tilt angles range from 54–61°. There are a spread of Al–O bond distances ranging from 1.80–1.85 Å. In the sixth Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with two equivalent AlO4 tetrahedra, corners with four MgO4 tetrahedra, edges with two equivalent MgO6 octahedra, and edges with four AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.88–2.05 Å. In the seventh Al3+ site, Al3+ is bonded to four O2- atoms to form AlO4 tetrahedra that share corners with three equivalent MgO6 octahedra and corners with nine AlO6 octahedra. The corner-sharing octahedra tilt angles range from 54–59°. There are a spread of Al–O bond distances ranging from 1.83–1.86 Å. In the eighth 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, an edgeedge with one MgO6 octahedra, and edges with five AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.90–2.02 Å. In the ninth Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with two equivalent AlO4 tetrahedra, corners with four 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 1.91–1.99 Å. In the tenth Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with two equivalent AlO4 tetrahedra, corners with four 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 1.91–1.99 Å. In the eleventh Al3+ site, Al3+ is bonded to six O2- 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 is two shorter (1.89 Å) and four longer (1.95 Å) Al–O bond length. In the twelfth Al3+ site, Al3+ is bonded to four O2- atoms to form AlO4 tetrahedra that share corners with three equivalent MgO6 octahedra and corners with nine AlO6 octahedra. The corner-sharing octahedra tilt angles range from 55–60°. There is three shorter (1.82 Å) and one longer (1.88 Å) Al–O bond length. There are twenty-four inequivalent O2- sites. In the first O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Mg2+ and two Al3+ atoms. In the second O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Mg2+ and three Al3+ atoms. In the third O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Mg2+ and two equivalent Al3+ atoms. In the fourth O2- site, O2- is bonded to two Mg2+ and two Al3+ atoms to form distorted OMg2Al2 trigonal pyramids that share corners with four OMgAl3 tetrahedra, corners with two OMg2Al2 trigonal pyramids, and edges with two OMg2Al2 trigonal pyramids. In the fifth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Al3+ atoms. In the sixth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Mg2+ and three Al3+ atoms. In the seventh O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to four Al3+ atoms. In the eighth O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Al3+ atoms. In the ninth O2- site, O2- is bonded to two Mg2+ and two equivalent Al3+ atoms to form distorted OMg2Al2 trigonal pyramids that share corners with four OMgAl3 tetrahedra, corners with two equivalent OMg2Al2 trigonal pyramids, and edges with two equivalent OMg2Al2 trigonal pyramids. In the tenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Al3+ atoms. In the eleventh O2- site, O2- is bonded to one Mg2+ and three Al3+ atoms to form distorted OMgAl3 tetrahedra that share corners with two equivalent OMgAl3 tetrahedra, corners with four OMg2Al2 trigonal pyramids, and edges with two equivalent OMgAl3 tetrahedra. In the twelfth O2- site, O2- is bonded to one Mg2+ and three Al3+ atoms to form distorted OMgAl3 tetrahedra that share corners with two OMgAl3 tetrahedra, corners with four OMg2Al2 trigonal pyramids, and edges with two OMgAl3 tetrahedra. In the thirteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Al3+ atoms. In the fourteenth O2- site, O2- is bonded to two Mg2+ and two equivalent Al3+ atoms to form distorted corner-sharing OMg2Al2 tetrahedra. In the fifteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Al3+ atoms. In the sixteenth O2- site, O2- is bonded to one Mg2+ and three Al3+ atoms to form distorted OMgAl3 trigonal pyramids that share corners with three OMg2Al2 tetrahedra, corners with three OMgAl3 trigonal pyramids, and edges with three OMgAl3 trigonal pyramids. In the seventeenth O2- site, O2- is bonded to one Mg2+ and three Al3+ atoms to form distorted OMgAl3 trigonal pyramids that share corners with three OMg2Al2 tetrahedra and corners with three OMgAl3 trigonal pyramids. In the eighteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Mg2+ and two equivalent Al3+ atoms. In the nineteenth O2- site, O2- is bonded to one Mg2+ and three Al3+ atoms to form a mixture of distorted corner and edge-sharing OMgAl3 trigonal pyramids. In the twentieth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Mg2+ and two Al3+ atoms. In the twenty-first O2- site, O2- is bonded to one Mg2+ and three Al3+ atoms to form distorted OMgAl3 trigonal pyramids that share corners with three OMg2Al2 tetrahedra, corners with three OMgAl3 trigonal pyramids, and edges with three OMgAl3 trigonal pyramids. In the twenty-second O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Al3+ atoms. In the twenty-third O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Al3+ atoms. In the twenty-fourth O2- site, O2- is bonded to one Mg2+ and three Al3+ atoms to form corner-sharing OMgAl3 tetrahedra.