Materials Data on NaSr2(FeAs)6 by Materials Project

Abstract

NaSr2(FeAs)6 is alpha bismuth trifluoride-derived structured and crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Na1+ is bonded in a body-centered cubic geometry to eight As3- atoms. There are four shorter (3.24 Å) and four longer (3.28 Å) Na–As bond lengths. Sr2+ is bonded in a body-centered cubic geometry to eight As3- atoms. There are a spread of Sr–As bond distances ranging from 3.20–3.35 Å. There are two inequivalent Fe+2.17+ sites. In the first Fe+2.17+ site, Fe+2.17+ is bonded to four As3- atoms to form a mixture of edge and corner-sharing FeAs4 tetrahedra. All Fe–As bond lengths are 2.32 Å. In the second Fe+2.17+ site, Fe+2.17+ is bonded to four As3- atoms to form a mixture of edge and corner-sharing FeAs4 tetrahedra. All Fe–As bond lengths are 2.34 Å. There are three inequivalent As3- sites. In the first As3- site, As3- is bonded in a 8-coordinate geometry to one Na1+, three equivalent Sr2+, and four Fe+2.17+ atoms. In the second As3- site, As3- is bonded in a 8-coordinate geometry to one Na1+, three equivalent Sr2+, and four equivalent Fe+2.17+ atoms. In the third As3- site, As3- is bonded in a 8-coordinate geometry to two equivalent Na1+, two equivalent Sr2+, and four Fe+2.17+ atoms.