DOI: 10.17188/1744536
title: Materials Data on KMg149 by Materials Project

description: KMg149 is alpha Samarium-derived structured and 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 eighteen MgMg12 cuboctahedra, edges with eighteen MgMg12 cuboctahedra, and faces with twenty MgMg12 cuboctahedra. All K–Mg bond lengths are 3.33 Å. There are twenty-seven inequivalent Mg sites. In the first Mg site, Mg is bonded to twelve Mg atoms to form MgMg12 cuboctahedra that share corners with eighteen MgKMg11 cuboctahedra, edges with eighteen MgMg12 cuboctahedra, and faces with twenty MgMg12 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.17–3.21 Å. In the second Mg site, Mg is bonded to twelve Mg atoms to form MgMg12 cuboctahedra that share corners with eighteen MgMg12 cuboctahedra, an edgeedge with one KMg12 cuboctahedra, edges with seventeen MgMg12 cuboctahedra, and faces with twenty MgMg12 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.18–3.22 Å. In the third Mg site, Mg is bonded to one K and eleven Mg atoms to form distorted MgKMg11 cuboctahedra that share corners with eighteen MgMg12 cuboctahedra, edges with eighteen MgMg12 cuboctahedra, a faceface with one KMg12 cuboctahedra, and faces with nineteen MgMg12 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.10–3.38 Å. In the fourth Mg site, Mg is bonded to twelve Mg atoms to form MgMg12 cuboctahedra that share a cornercorner with one KMg12 cuboctahedra, corners with seventeen MgMg12 cuboctahedra, edges with eighteen MgMg12 cuboctahedra, and faces with twenty MgMg12 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.12–3.22 Å. In the fifth Mg site, Mg is bonded to twelve Mg atoms to form MgMg12 cuboctahedra that share corners with eighteen MgMg12 cuboctahedra, an edgeedge with one KMg12 cuboctahedra, edges with seventeen MgMg12 cuboctahedra, and faces with twenty MgMg12 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.15–3.22 Å. In the sixth Mg site, Mg is bonded to twelve Mg atoms to form a mixture of face, edge, and corner-sharing MgMg12 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.17–3.22 Å. In the seventh Mg site, Mg is bonded to twelve Mg atoms to form MgMg12 cuboctahedra that share corners with eighteen MgMg12 cuboctahedra, edges with eighteen MgMg12 cuboctahedra, a faceface with one KMg12 cuboctahedra, and faces with nineteen MgMg12 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.17–3.23 Å. In the eighth Mg site, Mg is bonded to twelve Mg atoms to form a mixture of face, edge, and corner-sharing MgMg12 cuboctahedra. All Mg–Mg bond lengths are 3.20 Å. In the ninth Mg site, Mg is bonded to twelve Mg atoms to form a mixture of face, edge, and corner-sharing MgMg12 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.19–3.22 Å. In the tenth Mg site, Mg is bonded to twelve Mg atoms to form a mixture of face, edge, and corner-sharing MgMg12 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.17–3.20 Å. In the eleventh Mg site, Mg is bonded to twelve Mg atoms to form a mixture of face, edge, and corner-sharing MgMg12 cuboctahedra. There are two shorter (3.17 Å) and three longer (3.19 Å) Mg–Mg bond lengths. In the twelfth Mg site, Mg is bonded to twelve Mg atoms to form MgMg12 cuboctahedra that share corners with eighteen MgMg12 cuboctahedra, an edgeedge with one KMg12 cuboctahedra, edges with seventeen MgMg12 cuboctahedra, and faces with twenty MgMg12 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.15–3.21 Å. In the thirteenth Mg site, Mg is bonded to one K and eleven Mg atoms to form distorted MgKMg11 cuboctahedra that share corners with eighteen MgMg12 cuboctahedra, edges with eighteen MgMg12 cuboctahedra, a faceface with one KMg12 cuboctahedra, and faces with nineteen MgMg12 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.12–3.34 Å. In the fourteenth Mg site, Mg is bonded to twelve Mg atoms to form a mixture of face, edge, and corner-sharing MgMg12 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.18–3.20 Å. In the fifteenth Mg site, Mg is bonded to twelve Mg atoms to form a mixture of face, edge, and corner-sharing MgMg12 cuboctahedra. There are four shorter (3.19 Å) and three longer (3.20 Å) Mg–Mg bond lengths. In the sixteenth Mg site, Mg is bonded to twelve Mg atoms to form a mixture of face, edge, and corner-sharing MgMg12 cuboctahedra. There are seven shorter (3.19 Å) and two longer (3.20 Å) Mg–Mg bond lengths. In the seventeenth Mg site, Mg is bonded to twelve Mg atoms to form a mixture of face, edge, and corner-sharing MgMg12 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.17–3.20 Å. In the eighteenth Mg site, Mg is bonded to twelve Mg atoms to form MgMg12 cuboctahedra that share corners with eighteen MgMg12 cuboctahedra, edges with eighteen MgMg12 cuboctahedra, a faceface with one KMg12 cuboctahedra, and faces with nineteen MgMg12 cuboctahedra. There are three shorter (3.20 Å) and six longer (3.22 Å) Mg–Mg bond lengths. In the nineteenth Mg site, Mg is bonded to twelve Mg atoms to form a mixture of face, edge, and corner-sharing MgMg12 cuboctahedra. All Mg–Mg bond lengths are 3.19 Å. In the twentieth Mg site, Mg is bonded to twelve Mg atoms to form MgMg12 cuboctahedra that share a cornercorner with one KMg12 cuboctahedra, corners with seventeen MgMg12 cuboctahedra, edges with eighteen MgMg12 cuboctahedra, and faces with twenty MgMg12 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.18–3.23 Å. In the twenty-first Mg site, Mg is bonded to twelve Mg atoms to form a mixture of face, edge, and corner-sharing MgMg12 cuboctahedra. There are four shorter (3.20 Å) and two longer (3.21 Å) Mg–Mg bond lengths. In the twenty-second Mg site, Mg is bonded to twelve Mg atoms to form a mixture of face, edge, and corner-sharing MgMg12 cuboctahedra. There are two shorter (3.18 Å) and two longer (3.21 Å) Mg–Mg bond lengths. In the twenty-third Mg site, Mg is bonded to twelve Mg atoms to form a mixture of face, edge, and corner-sharing MgMg12 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.18–3.21 Å. In the twenty-fourth Mg site, Mg is bonded to twelve Mg atoms to form a mixture of face, edge, and corner-sharing MgMg12 cuboctahedra. In the twenty-fifth Mg site, Mg is bonded to twelve Mg atoms to form a mixture of face, edge, and corner-sharing MgMg12 cuboctahedra. All Mg–Mg bond lengths are 3.19 Å. In the twenty-sixth Mg site, Mg is bonded to twelve Mg atoms to form a mixture of face, edge, and corner-sharing MgMg12 cuboctahedra. Both Mg–Mg bond lengths are 3.19 Å. In the twenty-seventh Mg site, Mg is bonded to twelve Mg atoms to form a mixture of face, edge, and corner-sharing MgMg12 cuboctahedra. Both Mg–Mg bond lengths are 3.18 Å.