Mg3BiSb crystallizes in the trigonal P3m1 space group. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to three equivalent Bi(1) and three equivalent Sb(1) atoms to form MgBi3Sb3 octahedra that share corners with six equivalent Mg(3)Bi3Sb tetrahedra, corners with six equivalent Mg(2)BiSb3 tetrahedra, edges with six equivalent Mg(1)Bi3Sb3 octahedra, edges with three equivalent Mg(3)Bi3Sb tetrahedra, and edges with three equivalent Mg(2)BiSb3 tetrahedra. In the second Mg site, Mg(2) is bonded to one Bi(1) and three equivalent Sb(1) atoms to form distorted MgBiSb3 tetrahedra that share corners with six equivalent Mg(1)Bi3Sb3 octahedra, corners with six equivalent Mg(2)BiSb3 tetrahedra, edges with three equivalent Mg(1)Bi3Sb3 octahedra, and edges with three equivalent Mg(3)Bi3Sb tetrahedra. The corner-sharing octahedral tilt angles range from 10-58°. In the third Mg site, Mg(3) is bonded to three equivalent Bi(1) and one Sb(1) atom to form MgBi3Sb tetrahedra that share corners with six equivalent Mg(1)Bi3Sb3 octahedra, corners with six equivalent Mg(3)Bi3Sb tetrahedra, edges with three equivalent Mg(1)Bi3Sb3 octahedra, and edges with three equivalent Mg(2)BiSb3 tetrahedra. The corner-sharing octahedral tilt angles range from 9-59°. Bi(1) is bonded to one Mg(2), three equivalent Mg(1), and three equivalent Mg(3) atoms to form distorted BiMg7 pentagonal bipyramids that share corners with three equivalent Sb(1)Mg7 pentagonal bipyramids, edges with six equivalent Bi(1)Mg7 pentagonal bipyramids, and edges with six equivalent Sb(1)Mg7 pentagonal bipyramids. Sb(1) is bonded to one Mg(3), three equivalent Mg(1), and three equivalent Mg(2) atoms to form distorted SbMg7 pentagonal bipyramids that share corners with three equivalent Bi(1)Mg7 pentagonal bipyramids, edges with six equivalent Bi(1)Mg7 pentagonal bipyramids, and edges with six equivalent Sb(1)Mg7 pentagonal bipyramids.
Mg3BiSb crystallizes in the trigonal P3m1 space group. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to three equivalent Bi(1) and three equivalent Sb(1) atoms to form MgBi3Sb3 octahedra that share corners with six equivalent Mg(3)Bi3Sb tetrahedra, corners with six equivalent Mg(2)BiSb3 tetrahedra, edges with six equivalent Mg(1)Bi3Sb3 octahedra, edges with three equivalent Mg(3)Bi3Sb tetrahedra, and edges with three equivalent Mg(2)BiSb3 tetrahedra. All Mg(1)-Bi(1) bond lengths are 3.16 Å. All Mg(1)-Sb(1) bond lengths are 3.14 Å. In the second Mg site, Mg(2) is bonded to one Bi(1) and three equivalent Sb(1) atoms to form distorted MgBiSb3 tetrahedra that share corners with six equivalent Mg(1)Bi3Sb3 octahedra, corners with six equivalent Mg(2)BiSb3 tetrahedra, edges with three equivalent Mg(1)Bi3Sb3 octahedra, and edges with three equivalent Mg(3)Bi3Sb tetrahedra. The corner-sharing octahedral tilt angles range from 10-58°. The Mg(2)-Bi(1) bond length is 3.05 Å. All Mg(2)-Sb(1) bond lengths are 2.88 Å. In the third Mg site, Mg(3) is bonded to three equivalent Bi(1) and one Sb(1) atom to form MgBi3Sb tetrahedra that share corners with six equivalent Mg(1)Bi3Sb3 octahedra, corners with six equivalent Mg(3)Bi3Sb tetrahedra, edges with three equivalent Mg(1)Bi3Sb3 octahedra, and edges with three equivalent Mg(2)BiSb3 tetrahedra. The corner-sharing octahedral tilt angles range from 9-59°. All Mg(3)-Bi(1) bond lengths are 2.92 Å. The Mg(3)-Sb(1) bond length is 2.95 Å. Bi(1) is bonded to one Mg(2), three equivalent Mg(1), and three equivalent Mg(3) atoms to form distorted BiMg7 pentagonal bipyramids that share corners with three equivalent Sb(1)Mg7 pentagonal bipyramids, edges with six equivalent Bi(1)Mg7 pentagonal bipyramids, and edges with six equivalent Sb(1)Mg7 pentagonal bipyramids. Sb(1) is bonded to one Mg(3), three equivalent Mg(1), and three equivalent Mg(2) atoms to form distorted SbMg7 pentagonal bipyramids that share corners with three equivalent Bi(1)Mg7 pentagonal bipyramids, edges with six equivalent Bi(1)Mg7 pentagonal bipyramids, and edges with six equivalent Sb(1)Mg7 pentagonal bipyramids.