Materials Data on SrCaI4 by Materials Project

Abstract

SrCaI4 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Sr2+ is bonded to seven I1- atoms to form distorted SrI7 pentagonal bipyramids that share corners with three equivalent CaI5 trigonal bipyramids, edges with three equivalent SrI7 pentagonal bipyramids, and edges with three equivalent CaI5 trigonal bipyramids. There are a spread of Sr–I bond distances ranging from 3.22–3.52 Å. Ca2+ is bonded to five I1- atoms to form distorted CaI5 trigonal bipyramids that share corners with three equivalent SrI7 pentagonal bipyramids, corners with two equivalent CaI5 trigonal bipyramids, and edges with three equivalent SrI7 pentagonal bipyramids. There are a spread of Ca–I bond distances ranging from 2.99–3.24 Å. There are four inequivalent I1- sites. In the first I1- site, I1- is bonded in a distorted trigonal planar geometry to two equivalent Sr2+ and one Ca2+ atom. In the second I1- site, I1- is bonded in a 3-coordinate geometry to two equivalent Sr2+ and one Ca2+ atom. In the third I1- site, I1- is bonded to two equivalent Sr2+ and two equivalent Ca2+ atoms to form distorted edge-sharing ISr2Ca2 trigonal pyramids. In the fourth I1- site, I1- is bonded in a water-like geometry to one Sr2+ and one Ca2+ atom.