Mg6VNiO8 is alpha Po-derived structured and crystallizes in the tetragonal P4/mmm space group. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form MgO6 octahedra that share corners with two equivalent Mg(2)O6 octahedra, corners with four equivalent Mg(1)O6 octahedra, edges with four equivalent Ni(1)O6 octahedra, and edges with eight equivalent Mg(3)O6 octahedra. The corner-sharing octahedra are not tilted. In the second Mg site, Mg(2) is bonded to two equivalent O(2) and four equivalent O(4) atoms to form MgO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with four equivalent Mg(2)O6 octahedra, edges with four equivalent V(1)O6 octahedra, and edges with eight equivalent Mg(3)O6 octahedra. The corner-sharing octahedra are not tilted. In the third Mg site, Mg(3) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms to form MgO6 octahedra that share corners with six equivalent Mg(3)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mg(2)O6 octahedra, edges with two equivalent V(1)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, and edges with four equivalent Mg(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-1°. V(1) is bonded to two equivalent O(1) and four equivalent O(4) atoms to form VO6 octahedra that share corners with two equivalent Ni(1)O6 octahedra, corners with four equivalent V(1)O6 octahedra, edges with four equivalent Mg(2)O6 octahedra, and edges with eight equivalent Mg(3)O6 octahedra. The corner-sharing octahedra are not tilted. Ni(1) is bonded to two equivalent O(1) and four equivalent O(3) atoms to form NiO6 octahedra that share corners with two equivalent V(1)O6 octahedra, corners with four equivalent Ni(1)O6 octahedra, edges with four equivalent Mg(1)O6 octahedra, and edges with eight equivalent Mg(3)O6 octahedra. The corner-sharing octahedra are not tilted. There are four inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Mg(3), one V(1), and one Ni(1) atom to form OMg4VNi octahedra that share corners with six equivalent O(1)Mg4VNi octahedra, edges with four equivalent O(3)Mg4Ni2 octahedra, edges with four equivalent O(4)Mg4V2 octahedra, and edges with four equivalent O(2)Mg6 octahedra. The corner-sharing octahedral tilt angles range from 0-1°. In the second O site, O(2) is bonded to one Mg(1), one Mg(2), and four equivalent Mg(3) atoms to form OMg6 octahedra that share corners with six equivalent O(2)Mg6 octahedra, edges with four equivalent O(3)Mg4Ni2 octahedra, edges with four equivalent O(4)Mg4V2 octahedra, and edges with four equivalent O(1)Mg4VNi octahedra. The corner-sharing octahedral tilt angles range from 0-1°. In the third O site, O(3) is bonded to two equivalent Mg(1), two equivalent Mg(3), and two equivalent Ni(1) atoms to form OMg4Ni2 octahedra that share corners with two equivalent O(4)Mg4V2 octahedra, corners with four equivalent O(3)Mg4Ni2 octahedra, edges with four equivalent O(3)Mg4Ni2 octahedra, edges with four equivalent O(1)Mg4VNi octahedra, and edges with four equivalent O(2)Mg6 octahedra. The corner-sharing octahedra are not tilted. In the fourth O site, O(4) is bonded to two equivalent Mg(2), two equivalent Mg(3), and two equivalent V(1) atoms to form OMg4V2 octahedra that share corners with two equivalent O(3)Mg4Ni2 octahedra, corners with four equivalent O(4)Mg4V2 octahedra, edges with four equivalent O(4)Mg4V2 octahedra, edges with four equivalent O(1)Mg4VNi octahedra, and edges with four equivalent O(2)Mg6 octahedra. The corner-sharing octahedra are not tilted.
Mg6VNiO8 is alpha Po-derived structured and crystallizes in the tetragonal P4/mmm space group. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form MgO6 octahedra that share corners with two equivalent Mg(2)O6 octahedra, corners with four equivalent Mg(1)O6 octahedra, edges with four equivalent Ni(1)O6 octahedra, and edges with eight equivalent Mg(3)O6 octahedra. The corner-sharing octahedra are not tilted. Both Mg(1)-O(2) bond lengths are 2.13 Å. All Mg(1)-O(3) bond lengths are 2.14 Å. In the second Mg site, Mg(2) is bonded to two equivalent O(2) and four equivalent O(4) atoms to form MgO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with four equivalent Mg(2)O6 octahedra, edges with four equivalent V(1)O6 octahedra, and edges with eight equivalent Mg(3)O6 octahedra. The corner-sharing octahedra are not tilted. Both Mg(2)-O(2) bond lengths are 2.13 Å. All Mg(2)-O(4) bond lengths are 2.14 Å. In the third Mg site, Mg(3) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms to form MgO6 octahedra that share corners with six equivalent Mg(3)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mg(2)O6 octahedra, edges with two equivalent V(1)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, and edges with four equivalent Mg(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-1°. The Mg(3)-O(3) bond length is 2.11 Å. The Mg(3)-O(4) bond length is 2.15 Å. Both Mg(3)-O(1) bond lengths are 2.14 Å. Both Mg(3)-O(2) bond lengths are 2.14 Å. V(1) is bonded to two equivalent O(1) and four equivalent O(4) atoms to form VO6 octahedra that share corners with two equivalent Ni(1)O6 octahedra, corners with four equivalent V(1)O6 octahedra, edges with four equivalent Mg(2)O6 octahedra, and edges with eight equivalent Mg(3)O6 octahedra. The corner-sharing octahedra are not tilted. Both V(1)-O(1) bond lengths are 2.18 Å. All V(1)-O(4) bond lengths are 2.14 Å. Ni(1) is bonded to two equivalent O(1) and four equivalent O(3) atoms to form NiO6 octahedra that share corners with two equivalent V(1)O6 octahedra, corners with four equivalent Ni(1)O6 octahedra, edges with four equivalent Mg(1)O6 octahedra, and edges with eight equivalent Mg(3)O6 octahedra. The corner-sharing octahedra are not tilted. Both Ni(1)-O(1) bond lengths are 2.08 Å. All Ni(1)-O(3) bond lengths are 2.14 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Mg(3), one V(1), and one Ni(1) atom to form OMg4VNi octahedra that share corners with six equivalent O(1)Mg4VNi octahedra, edges with four equivalent O(3)Mg4Ni2 octahedra, edges with four equivalent O(4)Mg4V2 octahedra, and edges with four equivalent O(2)Mg6 octahedra. The corner-sharing octahedral tilt angles range from 0-1°. In the second O site, O(2) is bonded to one Mg(1), one Mg(2), and four equivalent Mg(3) atoms to form OMg6 octahedra that share corners with six equivalent O(2)Mg6 octahedra, edges with four equivalent O(3)Mg4Ni2 octahedra, edges with four equivalent O(4)Mg4V2 octahedra, and edges with four equivalent O(1)Mg4VNi octahedra. The corner-sharing octahedral tilt angles range from 0-1°. In the third O site, O(3) is bonded to two equivalent Mg(1), two equivalent Mg(3), and two equivalent Ni(1) atoms to form OMg4Ni2 octahedra that share corners with two equivalent O(4)Mg4V2 octahedra, corners with four equivalent O(3)Mg4Ni2 octahedra, edges with four equivalent O(3)Mg4Ni2 octahedra, edges with four equivalent O(1)Mg4VNi octahedra, and edges with four equivalent O(2)Mg6 octahedra. The corner-sharing octahedra are not tilted. In the fourth O site, O(4) is bonded to two equivalent Mg(2), two equivalent Mg(3), and two equivalent V(1) atoms to form OMg4V2 octahedra that share corners with two equivalent O(3)Mg4Ni2 octahedra, corners with four equivalent O(4)Mg4V2 octahedra, edges with four equivalent O(4)Mg4V2 octahedra, edges with four equivalent O(1)Mg4VNi octahedra, and edges with four equivalent O(2)Mg6 octahedra. The corner-sharing octahedra are not tilted.