Materials Data on K3Na2SnAs3 by Materials Project

Abstract

K3Na2SnAs3 is Matlockite-derived structured and crystallizes in the orthorhombic Cmce space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 5-coordinate geometry to five As3- atoms. There are a spread of K–As bond distances ranging from 3.42–3.77 Å. In the second K1+ site, K1+ is bonded in a 4-coordinate geometry to five As3- atoms. There are a spread of K–As bond distances ranging from 3.45–3.89 Å. There are two inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to four As3- atoms to form NaAs4 tetrahedra that share corners with two equivalent NaAs4 tetrahedra, corners with two equivalent SnAs4 tetrahedra, edges with two NaAs4 tetrahedra, and edges with two equivalent SnAs4 tetrahedra. There are two shorter (2.99 Å) and two longer (3.02 Å) Na–As bond lengths. In the second Na1+ site, Na1+ is bonded to four equivalent As3- atoms to form NaAs4 tetrahedra that share corners with two equivalent NaAs4 tetrahedra, corners with two equivalent SnAs4 tetrahedra, an edgeedge with one SnAs4 tetrahedra, and edges with three NaAs4 tetrahedra. There are two shorter (3.00 Å) and two longer (3.09 Å) Na–As bond lengths. Sn4+ is bonded to four As3- atoms to form SnAs4 tetrahedra that share corners with four NaAs4 tetrahedra, an edgeedge with one SnAs4 tetrahedra, and edges with three NaAs4 tetrahedra. There are two shorter (2.68 Å) and two longer (2.75 Å) Sn–As bond lengths. There are two inequivalent As3- sites. In the first As3- site, As3- is bonded in a 9-coordinate geometry to five K1+, three Na1+, and one Sn4+ atom. In the second As3- site, As3- is bonded in a 9-coordinate geometry to five K1+, two equivalent Na1+, and two equivalent Sn4+ atoms.