Ba3MgTaNbO9 is (Cubic) Perovskite-derived structured and crystallizes in the trigonal P3m1 space group. There are three inequivalent Ba sites. In the first Ba site, Ba(1) is bonded to three equivalent O(1), three equivalent O(2), and six equivalent O(3) atoms to form BaO12 cuboctahedra that share corners with three equivalent Ba(2)O12 cuboctahedra, corners with three equivalent Ba(3)O12 cuboctahedra, corners with six equivalent Ba(1)O12 cuboctahedra, faces with three equivalent Ba(2)O12 cuboctahedra, faces with three equivalent Ba(3)O12 cuboctahedra, faces with two equivalent Mg(1)O6 octahedra, faces with three equivalent Ta(1)O6 octahedra, and faces with three equivalent Nb(1)O6 octahedra. In the second Ba site, Ba(2) is bonded to three equivalent O(1), three equivalent O(3), and six equivalent O(2) atoms to form BaO12 cuboctahedra that share corners with three equivalent Ba(1)O12 cuboctahedra, corners with three equivalent Ba(3)O12 cuboctahedra, corners with six equivalent Ba(2)O12 cuboctahedra, faces with three equivalent Ba(1)O12 cuboctahedra, faces with three equivalent Ba(3)O12 cuboctahedra, faces with two equivalent Ta(1)O6 octahedra, faces with three equivalent Mg(1)O6 octahedra, and faces with three equivalent Nb(1)O6 octahedra. In the third Ba site, Ba(3) is bonded to three equivalent O(2), three equivalent O(3), and six equivalent O(1) atoms to form BaO12 cuboctahedra that share corners with three equivalent Ba(1)O12 cuboctahedra, corners with three equivalent Ba(2)O12 cuboctahedra, corners with six equivalent Ba(3)O12 cuboctahedra, faces with three equivalent Ba(1)O12 cuboctahedra, faces with three equivalent Ba(2)O12 cuboctahedra, faces with two equivalent Nb(1)O6 octahedra, faces with three equivalent Mg(1)O6 octahedra, and faces with three equivalent Ta(1)O6 octahedra. Mg(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form MgO6 octahedra that share corners with three equivalent Ta(1)O6 octahedra, corners with three equivalent Nb(1)O6 octahedra, faces with two equivalent Ba(1)O12 cuboctahedra, faces with three equivalent Ba(2)O12 cuboctahedra, and faces with three equivalent Ba(3)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 3-4°. Ta(1) is bonded to three equivalent O(1) and three equivalent O(3) atoms to form TaO6 octahedra that share corners with three equivalent Mg(1)O6 octahedra, corners with three equivalent Nb(1)O6 octahedra, faces with two equivalent Ba(2)O12 cuboctahedra, faces with three equivalent Ba(1)O12 cuboctahedra, and faces with three equivalent Ba(3)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-3°. Nb(1) is bonded to three equivalent O(2) and three equivalent O(3) atoms to form NbO6 octahedra that share corners with three equivalent Mg(1)O6 octahedra, corners with three equivalent Ta(1)O6 octahedra, faces with two equivalent Ba(3)O12 cuboctahedra, faces with three equivalent Ba(1)O12 cuboctahedra, and faces with three equivalent Ba(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-4°. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to one Ba(1), one Ba(2), two equivalent Ba(3), one Mg(1), and one Ta(1) atom. In the second O site, O(2) is bonded in a distorted linear geometry to one Ba(1), one Ba(3), two equivalent Ba(2), one Mg(1), and one Nb(1) atom. In the third O site, O(3) is bonded in a distorted linear geometry to one Ba(2), one Ba(3), two equivalent Ba(1), one Ta(1), and one Nb(1) atom.
Ba3MgTaNbO9 is (Cubic) Perovskite-derived structured and crystallizes in the trigonal P3m1 space group. There are three inequivalent Ba sites. In the first Ba site, Ba(1) is bonded to three equivalent O(1), three equivalent O(2), and six equivalent O(3) atoms to form BaO12 cuboctahedra that share corners with three equivalent Ba(2)O12 cuboctahedra, corners with three equivalent Ba(3)O12 cuboctahedra, corners with six equivalent Ba(1)O12 cuboctahedra, faces with three equivalent Ba(2)O12 cuboctahedra, faces with three equivalent Ba(3)O12 cuboctahedra, faces with two equivalent Mg(1)O6 octahedra, faces with three equivalent Ta(1)O6 octahedra, and faces with three equivalent Nb(1)O6 octahedra. All Ba(1)-O(1) bond lengths are 2.91 Å. All Ba(1)-O(2) bond lengths are 2.91 Å. All Ba(1)-O(3) bond lengths are 2.93 Å. In the second Ba site, Ba(2) is bonded to three equivalent O(1), three equivalent O(3), and six equivalent O(2) atoms to form BaO12 cuboctahedra that share corners with three equivalent Ba(1)O12 cuboctahedra, corners with three equivalent Ba(3)O12 cuboctahedra, corners with six equivalent Ba(2)O12 cuboctahedra, faces with three equivalent Ba(1)O12 cuboctahedra, faces with three equivalent Ba(3)O12 cuboctahedra, faces with two equivalent Ta(1)O6 octahedra, faces with three equivalent Mg(1)O6 octahedra, and faces with three equivalent Nb(1)O6 octahedra. All Ba(2)-O(1) bond lengths are 2.95 Å. All Ba(2)-O(3) bond lengths are 2.94 Å. All Ba(2)-O(2) bond lengths are 2.93 Å. In the third Ba site, Ba(3) is bonded to three equivalent O(2), three equivalent O(3), and six equivalent O(1) atoms to form BaO12 cuboctahedra that share corners with three equivalent Ba(1)O12 cuboctahedra, corners with three equivalent Ba(2)O12 cuboctahedra, corners with six equivalent Ba(3)O12 cuboctahedra, faces with three equivalent Ba(1)O12 cuboctahedra, faces with three equivalent Ba(2)O12 cuboctahedra, faces with two equivalent Nb(1)O6 octahedra, faces with three equivalent Mg(1)O6 octahedra, and faces with three equivalent Ta(1)O6 octahedra. All Ba(3)-O(2) bond lengths are 2.95 Å. All Ba(3)-O(3) bond lengths are 2.94 Å. All Ba(3)-O(1) bond lengths are 2.93 Å. Mg(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form MgO6 octahedra that share corners with three equivalent Ta(1)O6 octahedra, corners with three equivalent Nb(1)O6 octahedra, faces with two equivalent Ba(1)O12 cuboctahedra, faces with three equivalent Ba(2)O12 cuboctahedra, and faces with three equivalent Ba(3)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 3-4°. All Mg(1)-O(1) bond lengths are 2.14 Å. All Mg(1)-O(2) bond lengths are 2.15 Å. Ta(1) is bonded to three equivalent O(1) and three equivalent O(3) atoms to form TaO6 octahedra that share corners with three equivalent Mg(1)O6 octahedra, corners with three equivalent Nb(1)O6 octahedra, faces with two equivalent Ba(2)O12 cuboctahedra, faces with three equivalent Ba(1)O12 cuboctahedra, and faces with three equivalent Ba(3)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-3°. All Ta(1)-O(1) bond lengths are 1.95 Å. All Ta(1)-O(3) bond lengths are 2.10 Å. Nb(1) is bonded to three equivalent O(2) and three equivalent O(3) atoms to form NbO6 octahedra that share corners with three equivalent Mg(1)O6 octahedra, corners with three equivalent Ta(1)O6 octahedra, faces with two equivalent Ba(3)O12 cuboctahedra, faces with three equivalent Ba(1)O12 cuboctahedra, and faces with three equivalent Ba(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-4°. All Nb(1)-O(2) bond lengths are 1.96 Å. All Nb(1)-O(3) bond lengths are 2.13 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to one Ba(1), one Ba(2), two equivalent Ba(3), one Mg(1), and one Ta(1) atom. In the second O site, O(2) is bonded in a distorted linear geometry to one Ba(1), one Ba(3), two equivalent Ba(2), one Mg(1), and one Nb(1) atom. In the third O site, O(3) is bonded in a distorted linear geometry to one Ba(2), one Ba(3), two equivalent Ba(1), one Ta(1), and one Nb(1) atom.