Materials Data on Cs3Er2I9 by Materials Project
Cs3Er2I9 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are two inequivalent Cs1+ sites. In the first Cs1+ site, Cs1+ is bonded in a distorted q6 geometry to nine equivalent I1- atoms. There are three shorter (4.22 Å) and six longer (4.37 Å) Cs–I bond lengths. In the second Cs1+ site, Cs1+ is bonded to twelve I1- atoms to form CsI12 cuboctahedra that share corners with six equivalent CsI12 cuboctahedra and faces with six equivalent ErI6 octahedra. There are six shorter (4.35 Å) and six longer (4.36 Å) Cs–I bond lengths. Er3+ is bonded to six I1- atoms to form ErI6 octahedra that share faces with three equivalent CsI12 cuboctahedra and a faceface with one ErI6 octahedra. There are three shorter (2.92 Å) and three longer (3.13 Å) Er–I bond lengths. There are two inequivalent I1- sites. In the first I1- site, I1- is bonded in a distorted single-bond geometry to four Cs1+ and one Er3+ atom. In the second I1- site, I1- is bonded in a 2-coordinate geometry to two equivalent Cs1+ and two equivalent Er3+ atoms.