Materials Data on CaU2S5 by Materials Project

Abstract

CaU2S5 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Ca2+ is bonded to seven S2- atoms to form distorted edge-sharing CaS7 pentagonal bipyramids. There are a spread of Ca–S bond distances ranging from 2.69–2.94 Å. U4+ is bonded in a 8-coordinate geometry to eight S2- atoms. There are a spread of U–S bond distances ranging from 2.66–2.98 Å. There are four inequivalent S2- sites. In the first S2- site, S2- is bonded to one Ca2+ and four equivalent U4+ atoms to form distorted SCaU4 square pyramids that share corners with eight SCaU4 square pyramids, corners with four equivalent SCa2U2 tetrahedra, an edgeedge with one SCaU4 square pyramid, edges with four equivalent SCa2U2 tetrahedra, and a faceface with one SCaU4 square pyramid. In the second S2- site, S2- is bonded in a 5-coordinate geometry to one Ca2+ and four equivalent U4+ atoms. In the third S2- site, S2- is bonded to one Ca2+ and four equivalent U4+ atoms to form SCaU4 square pyramids that share corners with four equivalent SCaU4 square pyramids, corners with eight equivalent SCa2U2 tetrahedra, edges with three SCaU4 square pyramids, edges with two equivalent SCa2U2 tetrahedra, and a faceface with one SCaU4 square pyramid. In the fourth S2- site, S2- is bonded to two equivalent Ca2+ and two equivalent U4+ atoms to form distorted SCa2U2 tetrahedra that share corners with six SCaU4 square pyramids, corners with six equivalent SCa2U2 tetrahedra, edges with three SCaU4 square pyramids, and an edgeedge with one SCa2U2 tetrahedra.