Materials Data on KCeMg14 by Materials Project
KMg14Ce crystallizes in the hexagonal P-6m2 space group. The structure is three-dimensional. K is bonded to twelve Mg atoms to form KMg12 cuboctahedra that share corners with six equivalent KMg12 cuboctahedra, faces with two equivalent CeMg12 cuboctahedra, and faces with six equivalent MgMg12 cuboctahedra. There are six shorter (3.49 Å) and six longer (3.56 Å) K–Mg bond lengths. There are four inequivalent Mg sites. In the first Mg site, Mg is bonded in a distorted linear geometry to two equivalent K and two equivalent Mg atoms. Both Mg–Mg bond lengths are 3.45 Å. In the second Mg site, Mg is bonded in a 12-coordinate geometry to eight Mg and two equivalent Ce atoms. There are a spread of Mg–Mg bond distances ranging from 3.32–3.48 Å. Both Mg–Ce bond lengths are 3.56 Å. In the third Mg site, Mg is bonded in a 2-coordinate geometry to one K, four Mg, and one Ce atom. Both Mg–Mg bond lengths are 3.56 Å. The Mg–Ce bond length is 3.35 Å. In the fourth Mg site, Mg is bonded to twelve Mg atoms to form distorted MgMg12 cuboctahedra that share corners with six equivalent MgMg12 cuboctahedra, faces with two equivalent MgMg12 cuboctahedra, faces with three equivalent KMg12 cuboctahedra, and faces with three equivalent CeMg12 cuboctahedra. Ce is bonded to twelve Mg atoms to form CeMg12 cuboctahedra that share corners with six equivalent CeMg12 cuboctahedra, faces with two equivalent KMg12 cuboctahedra, and faces with six equivalent MgMg12 cuboctahedra.