Materials Data on CaMg2Ni9 by Materials Project

Abstract

CaMg2Ni9 crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Ca is bonded in a distorted hexagonal planar geometry to eighteen Ni atoms. There are six shorter (2.80 Å) and twelve longer (3.14 Å) Ca–Ni bond lengths. Mg is bonded in a 12-coordinate geometry to twelve Ni atoms. There are a spread of Mg–Ni bond distances ranging from 2.79–2.85 Å. There are three inequivalent Ni sites. In the first Ni site, Ni is bonded to two equivalent Ca, three equivalent Mg, and seven Ni atoms to form a mixture of edge, face, and corner-sharing NiCa2Mg3Ni7 cuboctahedra. There are a spread of Ni–Ni bond distances ranging from 2.39–2.45 Å. In the second Ni site, Ni is bonded to six equivalent Mg and six equivalent Ni atoms to form NiMg6Ni6 cuboctahedra that share corners with twelve equivalent NiCa2Mg3Ni7 cuboctahedra, edges with six equivalent NiMg6Ni6 cuboctahedra, and faces with eighteen equivalent NiCa2Mg3Ni7 cuboctahedra. In the third Ni site, Ni is bonded in a 12-coordinate geometry to three equivalent Ca and nine Ni atoms. All Ni–Ni bond lengths are 2.80 Å.