Materials Data on SrCa2(FeAs)6 by Materials Project

Abstract

SrCa2(FeAs)6 is alpha bismuth trifluoride-derived structured and crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Sr2+ is bonded in a body-centered cubic geometry to eight As3- atoms. All Sr–As bond lengths are 3.21 Å. Ca2+ is bonded in a body-centered cubic geometry to eight As3- atoms. There are a spread of Ca–As bond distances ranging from 3.18–3.24 Å. There are two inequivalent Fe2+ sites. In the first Fe2+ site, Fe2+ is bonded to four As3- atoms to form a mixture of edge and corner-sharing FeAs4 tetrahedra. There are two shorter (2.31 Å) and two longer (2.32 Å) Fe–As bond lengths. In the second Fe2+ site, Fe2+ is bonded to four As3- atoms to form a mixture of edge and corner-sharing FeAs4 tetrahedra. There are two shorter (2.31 Å) and two longer (2.32 Å) Fe–As bond lengths. There are three inequivalent As3- sites. In the first As3- site, As3- is bonded in a 4-coordinate geometry to one Sr2+, three equivalent Ca2+, and four Fe2+ atoms. In the second As3- site, As3- is bonded in a 4-coordinate geometry to two equivalent Sr2+, two equivalent Ca2+, and four Fe2+ atoms. In the third As3- site, As3- is bonded in a 4-coordinate geometry to one Sr2+, three equivalent Ca2+, and four equivalent Fe2+ atoms.