Materials Data on SrMg14B by Materials Project
SrMg14B crystallizes in the hexagonal P-6m2 space group. The structure is three-dimensional. Sr is bonded to twelve Mg atoms to form SrMg12 cuboctahedra that share corners with six equivalent SrMg12 cuboctahedra, edges with six equivalent MgSr2Mg10 cuboctahedra, and faces with twelve MgSr2Mg10 cuboctahedra. There are six shorter (3.21 Å) and six longer (3.38 Å) Sr–Mg bond lengths. There are four inequivalent Mg sites. In the first Mg site, Mg is bonded to two equivalent Sr and ten Mg atoms to form distorted MgSr2Mg10 cuboctahedra that share corners with six equivalent MgSr2Mg10 cuboctahedra, edges with two equivalent SrMg12 cuboctahedra, edges with eight MgSr2Mg10 cuboctahedra, faces with two equivalent SrMg12 cuboctahedra, and faces with six MgSr2Mg10 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.08–3.39 Å. In the second Mg site, Mg is bonded in a 10-coordinate geometry to ten Mg atoms. There are a spread of Mg–Mg bond distances ranging from 3.03–3.30 Å. In the third Mg site, Mg is bonded in a 12-coordinate geometry to one Sr, ten Mg, and one B atom. There are a spread of Mg–Mg bond distances ranging from 3.13–3.29 Å. The Mg–B bond length is 2.97 Å. In the fourth Mg site, Mg is bonded to twelve Mg atoms to form MgMg12 cuboctahedra that share corners with six equivalent MgMg12 cuboctahedra, edges with six equivalent MgSr2Mg10 cuboctahedra, faces with three equivalent SrMg12 cuboctahedra, and faces with five MgSr2Mg10 cuboctahedra. B is bonded in a 6-coordinate geometry to six equivalent Mg atoms.