Materials Data on Ca5(AlSb3)2 by Materials Project

Abstract

Ca5Al2Sb6 crystallizes in the orthorhombic Pbam space group. The structure is three-dimensional. there are three inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to six Sb+2.67- atoms to form CaSb6 octahedra that share corners with five CaSb6 octahedra, corners with seven equivalent CaSb7 pentagonal bipyramids, edges with two equivalent CaSb6 octahedra, edges with two equivalent CaSb7 pentagonal bipyramids, edges with four equivalent AlSb4 tetrahedra, a faceface with one CaSb6 octahedra, and a faceface with one CaSb7 pentagonal bipyramid. The corner-sharing octahedra tilt angles range from 33–51°. There are a spread of Ca–Sb bond distances ranging from 3.16–3.23 Å. In the second Ca2+ site, Ca2+ is bonded to seven Sb+2.67- atoms to form distorted CaSb7 pentagonal bipyramids that share corners with nine CaSb6 octahedra, corners with four equivalent AlSb4 tetrahedra, edges with two equivalent CaSb6 octahedra, edges with two equivalent CaSb7 pentagonal bipyramids, edges with two equivalent AlSb4 tetrahedra, faces with two CaSb6 octahedra, and faces with three equivalent CaSb7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 30–48°. There are a spread of Ca–Sb bond distances ranging from 3.26–3.51 Å. In the third Ca2+ site, Ca2+ is bonded to six Sb+2.67- atoms to form CaSb6 octahedra that share corners with six equivalent CaSb6 octahedra, corners with four equivalent CaSb7 pentagonal bipyramids, corners with eight equivalent AlSb4 tetrahedra, edges with two equivalent CaSb6 octahedra, faces with two equivalent CaSb6 octahedra, and faces with two equivalent CaSb7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 33–51°. There are two shorter (3.19 Å) and four longer (3.22 Å) Ca–Sb bond lengths. Al3+ is bonded to four Sb+2.67- atoms to form AlSb4 tetrahedra that share corners with four equivalent CaSb6 octahedra, corners with four equivalent CaSb7 pentagonal bipyramids, corners with two equivalent AlSb4 tetrahedra, edges with four equivalent CaSb6 octahedra, and edges with two equivalent CaSb7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 44–62°. There are a spread of Al–Sb bond distances ranging from 2.71–2.83 Å. There are three inequivalent Sb+2.67- sites. In the first Sb+2.67- site, Sb+2.67- is bonded to six Ca2+ and one Al3+ atom to form a mixture of distorted edge, corner, and face-sharing SbCa6Al pentagonal bipyramids. In the second Sb+2.67- site, Sb+2.67- is bonded in a 6-coordinate geometry to four Ca2+ and two equivalent Al3+ atoms. In the third Sb+2.67- site, Sb+2.67- is bonded in a 8-coordinate geometry to six Ca2+, one Al3+, and one Sb+2.67- atom. The Sb–Sb bond length is 2.90 Å.