Materials Data on KCa2Cd2Sb3 by Materials Project
KCa2Cd2Sb3 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. K1+ is bonded in a 7-coordinate geometry to two equivalent K1+ and five Sb3- atoms. Both K–K bond lengths are 3.53 Å. There are a spread of K–Sb bond distances ranging from 3.42–3.84 Å. There are two inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded in a 5-coordinate geometry to five Sb3- atoms. There are one shorter (3.26 Å) and four longer (3.40 Å) Ca–Sb bond lengths. In the second Ca2+ site, Ca2+ is bonded to six Sb3- atoms to form CaSb6 octahedra that share corners with two equivalent CaSb6 octahedra, corners with five equivalent CdSb4 tetrahedra, edges with two equivalent CaSb6 octahedra, edges with four equivalent CdSb4 tetrahedra, and a faceface with one CdSb4 tetrahedra. The corner-sharing octahedral tilt angles are 35°. There are a spread of Ca–Sb bond distances ranging from 3.22–3.54 Å. There are two inequivalent Cd2+ sites. In the first Cd2+ site, Cd2+ is bonded to four Sb3- atoms to form CdSb4 tetrahedra that share corners with five equivalent CaSb6 octahedra, corners with seven CdSb4 tetrahedra, and a faceface with one CaSb6 octahedra. The corner-sharing octahedra tilt angles range from 29–50°. There are a spread of Cd–Sb bond distances ranging from 2.90–3.00 Å. In the second Cd2+ site, Cd2+ is bonded to four Sb3- atoms to form CdSb4 tetrahedra that share corners with seven CdSb4 tetrahedra and edges with four equivalent CaSb6 octahedra. There are a spread of Cd–Sb bond distances ranging from 2.83–2.99 Å. There are three inequivalent Sb3- sites. In the first Sb3- site, Sb3- is bonded in a 8-coordinate geometry to five Ca2+ and three Cd2+ atoms. In the second Sb3- site, Sb3- is bonded in a 7-coordinate geometry to two equivalent K1+, two equivalent Ca2+, and three Cd2+ atoms. In the third Sb3- site, Sb3- is bonded in a 9-coordinate geometry to three equivalent K1+, four Ca2+, and two Cd2+ atoms.