Materials Data on Ca31Sn20 by Materials Project

Abstract

Ca31Sn20 crystallizes in the tetragonal I4/mcm space group. The structure is three-dimensional. there are seven inequivalent Ca sites. In the first Ca site, Ca is bonded in a 6-coordinate geometry to six Sn atoms. There are a spread of Ca–Sn bond distances ranging from 3.14–3.48 Å. In the second Ca site, Ca is bonded in a 5-coordinate geometry to five Sn atoms. There are a spread of Ca–Sn bond distances ranging from 3.26–3.68 Å. In the third Ca site, Ca is bonded to four Sn atoms to form distorted CaSn4 tetrahedra that share an edgeedge with one CaSn6 octahedra and an edgeedge with one CaSn4 tetrahedra. There are two shorter (3.28 Å) and two longer (3.29 Å) Ca–Sn bond lengths. In the fourth Ca site, Ca is bonded to six Sn atoms to form distorted CaSn6 octahedra that share an edgeedge with one CaSn6 octahedra and an edgeedge with one CaSn4 tetrahedra. There are a spread of Ca–Sn bond distances ranging from 3.35–3.53 Å. In the fifth Ca site, Ca is bonded in a 6-coordinate geometry to six Sn atoms. There are a spread of Ca–Sn bond distances ranging from 3.22–3.53 Å. In the sixth Ca site, Ca is bonded in a 4-coordinate geometry to four Sn atoms. There are two shorter (3.06 Å) and two longer (3.30 Å) Ca–Sn bond lengths. In the seventh Ca site, Ca is bonded to four equivalent Sn atoms to form distorted edge-sharing CaSn4 tetrahedra. All Ca–Sn bond lengths are 3.19 Å. There are eight inequivalent Sn sites. In the first Sn site, Sn is bonded in a 9-coordinate geometry to eight Ca and one Sn atom. The Sn–Sn bond length is 3.19 Å. In the second Sn site, Sn is bonded in a 9-coordinate geometry to eight Ca and one Sn atom. The Sn–Sn bond length is 3.13 Å. In the third Sn site, Sn is bonded in a 9-coordinate geometry to eight Ca atoms. In the fourth Sn site, Sn is bonded in a body-centered cubic geometry to eight equivalent Ca atoms. In the fifth Sn site, Sn is bonded in a 10-coordinate geometry to eight equivalent Ca and two equivalent Sn atoms. Both Sn–Sn bond lengths are 3.10 Å. In the sixth Sn site, Sn is bonded in a 10-coordinate geometry to eight Ca and one Sn atom. In the seventh Sn site, Sn is bonded in a 9-coordinate geometry to eight Ca and one Sn atom. In the eighth Sn site, Sn is bonded in a 10-coordinate geometry to ten Ca atoms.