Materials Data on Na2Sr3As4 by Materials Project

Abstract

Na2Sr3As4 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are two inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a distorted trigonal non-coplanar geometry to three As2- atoms. There are a spread of Na–As bond distances ranging from 2.97–3.19 Å. In the second Na1+ site, Na1+ is bonded to four As2- atoms to form distorted NaAs4 tetrahedra that share corners with three equivalent SrAs5 square pyramids, corners with two equivalent NaAs4 tetrahedra, and edges with two equivalent SrAs5 square pyramids. There are a spread of Na–As bond distances ranging from 2.91–3.15 Å. There are three inequivalent Sr2+ sites. In the first Sr2+ site, Sr2+ is bonded in a 7-coordinate geometry to seven As2- atoms. There are a spread of Sr–As bond distances ranging from 3.12–3.65 Å. In the second Sr2+ site, Sr2+ is bonded in a 6-coordinate geometry to six As2- atoms. There are a spread of Sr–As bond distances ranging from 3.02–3.22 Å. In the third Sr2+ site, Sr2+ is bonded to five As2- atoms to form distorted SrAs5 square pyramids that share corners with two equivalent SrAs5 square pyramids, corners with three equivalent NaAs4 tetrahedra, an edgeedge with one SrAs5 square pyramid, and edges with two equivalent NaAs4 tetrahedra. There are a spread of Sr–As bond distances ranging from 3.07–3.54 Å. There are four inequivalent As2- sites. In the first As2- site, As2- is bonded in a 8-coordinate geometry to three Na1+ and five Sr2+ atoms. In the second As2- site, As2- is bonded in a 7-coordinate geometry to two Na1+, four Sr2+, and one As2- atom. The As–As bond length is 2.59 Å. In the third As2- site, As2- is bonded in a 8-coordinate geometry to two Na1+, five Sr2+, and one As2- atom. The As–As bond length is 2.51 Å. In the fourth As2- site, As2- is bonded in a 6-coordinate geometry to four Sr2+ and two As2- atoms.