DOE OSTI2020
Ba3Cd2Sb4 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are two inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded to seven Sb+2.50- atoms to form distorted BaSb7 pentagonal bipyramids that share corners with six equivalent BaSb6 octahedra, corners with seven equivalent CdSb4 tetrahedra, an edgeedge with one BaSb6 octahedra, edges with four equivalent BaSb7 pentagonal bipyramids, edges with three equivalent CdSb4 tetrahedra, a faceface with one BaSb6 octahedra, and faces with three equivalent BaSb7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 39–46°. There are a spread of Ba–Sb bond distances ranging from 3.59–3.81 Å. In the second Ba2+ site, Ba2+ is bonded to six Sb+2.50- atoms to form BaSb6 octahedra that share corners with twelve equivalent BaSb7 pentagonal bipyramids, corners with two equivalent CdSb4 tetrahedra, edges with two equivalent BaSb6 octahedra, edges with two equivalent BaSb7 pentagonal bipyramids, edges with four equivalent CdSb4 tetrahedra, and faces with two equivalent BaSb7 pentagonal bipyramids. There are two shorter (3.49 Å) and four longer (3.50 Å) Ba–Sb bond lengths. Cd2+ is bonded to four Sb+2.50- atoms to form CdSb4 tetrahedra that share a cornercorner with one BaSb6 octahedra, corners with seven equivalent BaSb7 pentagonal bipyramids, corners with two equivalent CdSb4 tetrahedra, edges with two equivalent BaSb6 octahedra, edges with three equivalent BaSb7 pentagonal bipyramids, and edges with two equivalent CdSb4 tetrahedra. The corner-sharing octahedral tilt angles are 48°. There are a spread of Cd–Sb bond distances ranging from 2.96–3.02 Å. There are two inequivalent Sb+2.50- sites. In the first Sb+2.50- site, Sb+2.50- is bonded in a 8-coordinate geometry to six Ba2+, one Cd2+, and one Sb+2.50- atom. The Sb–Sb bond length is 2.88 Å. In the second Sb+2.50- site, Sb+2.50- is bonded in a 7-coordinate geometry to four Ba2+ and three equivalent Cd2+ atoms.