Materials Data on Mg6Cu16Si7 by Materials Project

Abstract

Mg6Cu16Si7 crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Mg2+ is bonded in a distorted square co-planar geometry to four equivalent Si4- atoms. All Mg–Si bond lengths are 2.97 Å. There are two inequivalent Cu1+ sites. In the first Cu1+ site, Cu1+ is bonded in a trigonal planar geometry to three equivalent Si4- atoms. All Cu–Si bond lengths are 2.38 Å. In the second Cu1+ site, Cu1+ is bonded to four Si4- atoms to form a mixture of distorted corner and edge-sharing CuSi4 tetrahedra. There are one shorter (2.42 Å) and three longer (2.56 Å) Cu–Si bond lengths. There are two inequivalent Si4- sites. In the first Si4- site, Si4- is bonded to four equivalent Mg2+ and eight Cu1+ atoms to form a mixture of corner and face-sharing SiMg4Cu8 cuboctahedra. In the second Si4- site, Si4- is bonded in a body-centered cubic geometry to eight equivalent Cu1+ atoms.