MgAl2O4 is Spinel-like structured and crystallizes in the trigonal R3m space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(2) and three equivalent O(1) atoms to form MgO4 tetrahedra that share corners with three equivalent Mg(2)O6 octahedra and corners with nine equivalent Al(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 56-62°. In the second Mg site, Mg(2) is bonded to three equivalent O(1) and three equivalent O(4) atoms to form MgO6 octahedra that share corners with three equivalent Mg(1)O4 tetrahedra, corners with three equivalent Al(2)O4 tetrahedra, and edges with six equivalent Al(1)O6 octahedra. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(2), one O(3), two equivalent O(1), and two equivalent O(4) atoms to form AlO6 octahedra that share corners with three equivalent Mg(1)O4 tetrahedra, corners with three equivalent Al(2)O4 tetrahedra, edges with two equivalent Mg(2)O6 octahedra, and edges with four equivalent Al(1)O6 octahedra. In the second Al site, Al(2) is bonded to one O(3) and three equivalent O(4) atoms to form AlO4 tetrahedra that share corners with three equivalent Mg(2)O6 octahedra and corners with nine equivalent Al(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 57-59°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Mg(2), and two equivalent Al(1) atoms. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1) and three equivalent Al(1) atoms. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to one Al(2) and three equivalent Al(1) atoms. In the fourth O site, O(4) is bonded in a rectangular see-saw-like geometry to one Mg(2), one Al(2), and two equivalent Al(1) atoms.
MgAl2O4 is Spinel-like structured and crystallizes in the trigonal R3m space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(2) and three equivalent O(1) atoms to form MgO4 tetrahedra that share corners with three equivalent Mg(2)O6 octahedra and corners with nine equivalent Al(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 56-62°. The Mg(1)-O(2) bond length is 1.96 Å. All Mg(1)-O(1) bond lengths are 1.93 Å. In the second Mg site, Mg(2) is bonded to three equivalent O(1) and three equivalent O(4) atoms to form MgO6 octahedra that share corners with three equivalent Mg(1)O4 tetrahedra, corners with three equivalent Al(2)O4 tetrahedra, and edges with six equivalent Al(1)O6 octahedra. All Mg(2)-O(1) bond lengths are 2.02 Å. All Mg(2)-O(4) bond lengths are 2.07 Å. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(2), one O(3), two equivalent O(1), and two equivalent O(4) atoms to form AlO6 octahedra that share corners with three equivalent Mg(1)O4 tetrahedra, corners with three equivalent Al(2)O4 tetrahedra, edges with two equivalent Mg(2)O6 octahedra, and edges with four equivalent Al(1)O6 octahedra. The Al(1)-O(2) bond length is 1.93 Å. The Al(1)-O(3) bond length is 2.04 Å. Both Al(1)-O(1) bond lengths are 1.87 Å. Both Al(1)-O(4) bond lengths are 1.98 Å. In the second Al site, Al(2) is bonded to one O(3) and three equivalent O(4) atoms to form AlO4 tetrahedra that share corners with three equivalent Mg(2)O6 octahedra and corners with nine equivalent Al(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 57-59°. The Al(2)-O(3) bond length is 1.91 Å. All Al(2)-O(4) bond lengths are 1.83 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Mg(2), and two equivalent Al(1) atoms. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1) and three equivalent Al(1) atoms. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to one Al(2) and three equivalent Al(1) atoms. In the fourth O site, O(4) is bonded in a rectangular see-saw-like geometry to one Mg(2), one Al(2), and two equivalent Al(1) atoms.