Materials Data on K4Sr2SnAs4 by Materials Project

Abstract

K4Sr2SnAs4 crystallizes in the hexagonal P6_3cm space group. The structure is three-dimensional. there are three inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 4-coordinate geometry to four As3- atoms. There are a spread of K–As bond distances ranging from 3.26–3.58 Å. In the second K1+ site, K1+ is bonded to four As3- atoms to form distorted KAs4 trigonal pyramids that share corners with two equivalent SnAs4 tetrahedra, corners with six equivalent KAs4 trigonal pyramids, and an edgeedge with one SnAs4 tetrahedra. There are a spread of K–As bond distances ranging from 3.22–3.38 Å. In the third K1+ site, K1+ is bonded in a 3-coordinate geometry to three As3- atoms. There are two shorter (3.44 Å) and one longer (3.48 Å) K–As bond lengths. Sr2+ is bonded in a 6-coordinate geometry to six As3- atoms. There are a spread of Sr–As bond distances ranging from 3.20–3.80 Å. Sn4+ is bonded to four As3- atoms to form SnAs4 tetrahedra that share corners with two equivalent KAs4 trigonal pyramids and an edgeedge with one KAs4 trigonal pyramid. There are a spread of Sn–As bond distances ranging from 2.66–2.69 Å. There are three inequivalent As3- sites. In the first As3- site, As3- is bonded in a 8-coordinate geometry to three equivalent K1+, four equivalent Sr2+, and one Sn4+ atom. In the second As3- site, As3- is bonded in a 7-coordinate geometry to four K1+, four equivalent Sr2+, and one Sn4+ atom. In the third As3- site, As3- is bonded in a 7-coordinate geometry to four K1+, two equivalent Sr2+, and one Sn4+ atom.