Materials Data on Ca3Al7Ag2 by Materials Project

Abstract

Ca3Ag2Al7 is Frank-Kasper $\mu$ Phase-derived structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are two inequivalent Ca sites. In the first Ca site, Ca is bonded in a distorted hexagonal planar geometry to six equivalent Ag and twelve equivalent Al atoms. All Ca–Ag bond lengths are 3.26 Å. All Ca–Al bond lengths are 3.59 Å. In the second Ca site, Ca is bonded in a 12-coordinate geometry to twelve Al atoms. There are a spread of Ca–Al bond distances ranging from 3.26–3.31 Å. Ag is bonded in a 9-coordinate geometry to three equivalent Ca and six equivalent Al atoms. There are three shorter (2.72 Å) and three longer (2.78 Å) Ag–Al bond lengths. There are two inequivalent Al sites. In the first Al site, Al is bonded in a 12-coordinate geometry to five Ca, two equivalent Ag, and five Al atoms. There are a spread of Al–Al bond distances ranging from 2.77–2.87 Å. In the second Al site, Al is bonded to six equivalent Ca and six equivalent Al atoms to form edge-sharing AlCa6Al6 cuboctahedra.