Materials Data on CaCu9Sn4 by Materials Project
CaCu9Sn4 is Bergman Structure: Mg32(Al,Zn)49 Bergman-like structured and crystallizes in the tetragonal I4/mcm space group. The structure is three-dimensional. Ca is bonded in a 8-coordinate geometry to sixteen Cu and eight equivalent Sn atoms. There are eight shorter (3.60 Å) and eight longer (3.65 Å) Ca–Cu bond lengths. All Ca–Sn bond lengths are 3.52 Å. There are three inequivalent Cu sites. In the first Cu site, Cu is bonded in a 12-coordinate geometry to two equivalent Ca, six Cu, and four equivalent Sn atoms. There are a spread of Cu–Cu bond distances ranging from 2.56–2.99 Å. There are two shorter (2.75 Å) and two longer (2.79 Å) Cu–Sn bond lengths. In the second Cu site, Cu is bonded to two equivalent Ca, six Cu, and four equivalent Sn atoms to form a mixture of distorted corner, edge, and face-sharing CuCa2Cu6Sn4 cuboctahedra. There are a spread of Cu–Cu bond distances ranging from 2.54–2.66 Å. There are a spread of Cu–Sn bond distances ranging from 2.60–2.70 Å. In the third Cu site, Cu is bonded to eight Cu and four equivalent Sn atoms to form a mixture of corner and face-sharing CuCu8Sn4 cuboctahedra. All Cu–Sn bond lengths are 2.77 Å. Sn is bonded in a 11-coordinate geometry to two equivalent Ca and nine Cu atoms.