BaMg6NbO8 is Caswellsilverite-derived structured and crystallizes in the tetragonal P4/mmm space group. Ba(1) is bonded to two equivalent O(1) and four equivalent O(3) atoms to form BaO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with four equivalent Ba(1)O6 octahedra, edges with four equivalent Nb(1)O6 octahedra, and edges with eight equivalent Mg(3)O6 octahedra. The corner-sharing octahedra are not tilted. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent O(1) and four equivalent O(4) atoms to form MgO6 octahedra that share corners with two equivalent Ba(1)O6 octahedra, corners with four equivalent Mg(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. 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 Nb(1)O6 octahedra, corners with four equivalent Mg(2)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. 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 Ba(1)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mg(2)O6 octahedra, edges with two equivalent Nb(1)O6 octahedra, and edges with four equivalent Mg(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-6°. Nb(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form NbO6 octahedra that share corners with two equivalent Mg(2)O6 octahedra, corners with four equivalent Nb(1)O6 octahedra, edges with four equivalent Ba(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 one Ba(1), one Mg(1), and four equivalent Mg(3) atoms to form OBaMg5 octahedra that share corners with six equivalent O(1)BaMg5 octahedra, edges with four equivalent O(3)Ba2Mg2Nb2 octahedra, edges with four equivalent O(2)Mg5Nb octahedra, and edges with four equivalent O(4)Mg6 octahedra. The corner-sharing octahedral tilt angles range from 0-6°. In the second O site, O(2) is bonded to one Mg(2), four equivalent Mg(3), and one Nb(1) atom to form OMg5Nb octahedra that share corners with six equivalent O(2)Mg5Nb octahedra, edges with four equivalent O(3)Ba2Mg2Nb2 octahedra, edges with four equivalent O(1)BaMg5 octahedra, and edges with four equivalent O(4)Mg6 octahedra. The corner-sharing octahedral tilt angles range from 0-3°. In the third O site, O(3) is bonded to two equivalent Ba(1), two equivalent Mg(3), and two equivalent Nb(1) atoms to form OBa2Mg2Nb2 octahedra that share corners with two equivalent O(4)Mg6 octahedra, corners with four equivalent O(3)Ba2Mg2Nb2 octahedra, edges with four equivalent O(3)Ba2Mg2Nb2 octahedra, edges with four equivalent O(1)BaMg5 octahedra, and edges with four equivalent O(2)Mg5Nb octahedra. The corner-sharing octahedra are not tilted. In the fourth O site, O(4) is bonded to two equivalent Mg(1), two equivalent Mg(2), and two equivalent Mg(3) atoms to form OMg6 octahedra that share corners with two equivalent O(3)Ba2Mg2Nb2 octahedra, corners with four equivalent O(4)Mg6 octahedra, edges with four equivalent O(1)BaMg5 octahedra, edges with four equivalent O(2)Mg5Nb octahedra, and edges with four equivalent O(4)Mg6 octahedra. The corner-sharing octahedra are not tilted.
BaMg6NbO8 is Caswellsilverite-derived structured and crystallizes in the tetragonal P4/mmm space group. Ba(1) is bonded to two equivalent O(1) and four equivalent O(3) atoms to form BaO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with four equivalent Ba(1)O6 octahedra, edges with four equivalent Nb(1)O6 octahedra, and edges with eight equivalent Mg(3)O6 octahedra. The corner-sharing octahedra are not tilted. Both Ba(1)-O(1) bond lengths are 2.54 Å. All Ba(1)-O(3) bond lengths are 2.34 Å. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent O(1) and four equivalent O(4) atoms to form MgO6 octahedra that share corners with two equivalent Ba(1)O6 octahedra, corners with four equivalent Mg(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 Mg(1)-O(1) bond lengths are 1.94 Å. All Mg(1)-O(4) bond lengths are 2.34 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 Nb(1)O6 octahedra, corners with four equivalent Mg(2)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 Mg(2)-O(2) bond lengths are 2.13 Å. All Mg(2)-O(4) bond lengths are 2.34 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 Ba(1)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mg(2)O6 octahedra, edges with two equivalent Nb(1)O6 octahedra, and edges with four equivalent Mg(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-6°. The Mg(3)-O(3) bond length is 2.43 Å. The Mg(3)-O(4) bond length is 2.06 Å. Both Mg(3)-O(1) bond lengths are 2.34 Å. Both Mg(3)-O(2) bond lengths are 2.34 Å. Nb(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form NbO6 octahedra that share corners with two equivalent Mg(2)O6 octahedra, corners with four equivalent Nb(1)O6 octahedra, edges with four equivalent Ba(1)O6 octahedra, and edges with eight equivalent Mg(3)O6 octahedra. The corner-sharing octahedra are not tilted. Both Nb(1)-O(2) bond lengths are 2.36 Å. All Nb(1)-O(3) bond lengths are 2.34 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Ba(1), one Mg(1), and four equivalent Mg(3) atoms to form OBaMg5 octahedra that share corners with six equivalent O(1)BaMg5 octahedra, edges with four equivalent O(3)Ba2Mg2Nb2 octahedra, edges with four equivalent O(2)Mg5Nb octahedra, and edges with four equivalent O(4)Mg6 octahedra. The corner-sharing octahedral tilt angles range from 0-6°. In the second O site, O(2) is bonded to one Mg(2), four equivalent Mg(3), and one Nb(1) atom to form OMg5Nb octahedra that share corners with six equivalent O(2)Mg5Nb octahedra, edges with four equivalent O(3)Ba2Mg2Nb2 octahedra, edges with four equivalent O(1)BaMg5 octahedra, and edges with four equivalent O(4)Mg6 octahedra. The corner-sharing octahedral tilt angles range from 0-3°. In the third O site, O(3) is bonded to two equivalent Ba(1), two equivalent Mg(3), and two equivalent Nb(1) atoms to form OBa2Mg2Nb2 octahedra that share corners with two equivalent O(4)Mg6 octahedra, corners with four equivalent O(3)Ba2Mg2Nb2 octahedra, edges with four equivalent O(3)Ba2Mg2Nb2 octahedra, edges with four equivalent O(1)BaMg5 octahedra, and edges with four equivalent O(2)Mg5Nb octahedra. The corner-sharing octahedra are not tilted. In the fourth O site, O(4) is bonded to two equivalent Mg(1), two equivalent Mg(2), and two equivalent Mg(3) atoms to form OMg6 octahedra that share corners with two equivalent O(3)Ba2Mg2Nb2 octahedra, corners with four equivalent O(4)Mg6 octahedra, edges with four equivalent O(1)BaMg5 octahedra, edges with four equivalent O(2)Mg5Nb octahedra, and edges with four equivalent O(4)Mg6 octahedra. The corner-sharing octahedra are not tilted.