DOE OSTI2020
Cs2AgI3 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two inequivalent Cs1+ sites. In the first Cs1+ site, Cs1+ is bonded to seven I1- atoms to form distorted CsI7 pentagonal bipyramids that share corners with four equivalent CsI7 pentagonal bipyramids, corners with three equivalent AgI4 tetrahedra, edges with eight CsI7 pentagonal bipyramids, edges with three equivalent AgI4 tetrahedra, and faces with two equivalent CsI7 pentagonal bipyramids. There are a spread of Cs–I bond distances ranging from 3.90–4.03 Å. In the second Cs1+ site, Cs1+ is bonded to seven I1- atoms to form distorted CsI7 pentagonal bipyramids that share corners with six CsI7 pentagonal bipyramids, a cornercorner with one AgI4 tetrahedra, edges with ten CsI7 pentagonal bipyramids, and edges with four equivalent AgI4 tetrahedra. There are a spread of Cs–I bond distances ranging from 3.88–3.99 Å. Ag1+ is bonded to four I1- atoms to form AgI4 tetrahedra that share corners with four CsI7 pentagonal bipyramids, corners with two equivalent AgI4 tetrahedra, and edges with seven CsI7 pentagonal bipyramids. There are a spread of Ag–I bond distances ranging from 2.86–2.95 Å. There are three inequivalent I1- sites. In the first I1- site, I1- is bonded to five Cs1+ and one Ag1+ atom to form a mixture of distorted corner, edge, and face-sharing ICs5Ag octahedra. The corner-sharing octahedra tilt angles range from 26–62°. In the second I1- site, I1- is bonded to five Cs1+ and one Ag1+ atom to form a mixture of distorted corner, edge, and face-sharing ICs5Ag octahedra. The corner-sharing octahedra tilt angles range from 15–57°. In the third I1- site, I1- is bonded to four Cs1+ and two equivalent Ag1+ atoms to form a mixture of distorted corner, edge, and face-sharing ICs4Ag2 octahedra. The corner-sharing octahedra tilt angles range from 15–62°.