Materials Data on Ba(MgSn)2 by Materials Project
BaMg2Sn2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. there are two inequivalent Ba sites. In the first Ba site, Ba is bonded in a 12-coordinate geometry to eight Mg and eight Sn atoms. There are four shorter (3.75 Å) and four longer (3.98 Å) Ba–Mg bond lengths. There are four shorter (3.81 Å) and four longer (3.85 Å) Ba–Sn bond lengths. In the second Ba site, Ba is bonded in a 8-coordinate geometry to eight Mg and eight Sn atoms. There are four shorter (3.91 Å) and four longer (4.01 Å) Ba–Mg bond lengths. There are four shorter (3.76 Å) and four longer (3.82 Å) Ba–Sn bond lengths. There are three inequivalent Mg sites. In the first Mg site, Mg is bonded to four Ba and four Sn atoms to form MgBa4Sn4 tetrahedra that share corners with six equivalent MgBa4Sn4 tetrahedra, corners with six equivalent SnBa4Mg4 tetrahedra, an edgeedge with one SnBa4Mg4 tetrahedra, edges with five MgBa4Sn4 tetrahedra, and faces with four equivalent MgBa4Sn4 tetrahedra. There are two shorter (2.95 Å) and two longer (2.97 Å) Mg–Sn bond lengths. In the second Mg site, Mg is bonded to four equivalent Ba and four equivalent Sn atoms to form a mixture of edge, corner, and face-sharing MgBa4Sn4 tetrahedra. All Mg–Sn bond lengths are 2.95 Å. In the third Mg site, Mg is bonded in a 5-coordinate geometry to four equivalent Ba and five Sn atoms. There are one shorter (2.85 Å) and four longer (2.95 Å) Mg–Sn bond lengths. There are four inequivalent Sn sites. In the first Sn site, Sn is bonded in a 9-coordinate geometry to four equivalent Ba and five Mg atoms. In the second Sn site, Sn is bonded to four equivalent Ba and four equivalent Mg atoms to form distorted SnBa4Mg4 tetrahedra that share corners with twelve equivalent MgBa4Sn4 tetrahedra, edges with two equivalent MgBa4Sn4 tetrahedra, edges with four equivalent SnBa4Mg4 tetrahedra, and faces with four equivalent SnBa4Mg4 tetrahedra. In the third Sn site, Sn is bonded in a 9-coordinate geometry to four equivalent Ba, four equivalent Mg, and one Sn atom. The Sn–Sn bond length is 2.92 Å. In the fourth Sn site, Sn is bonded in a 9-coordinate geometry to four equivalent Ba, four equivalent Mg, and one Sn atom.