Materials Data on RbMg6Sb by Materials Project

Abstract

RbMg6Sb crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. Rb is bonded to ten Mg and two equivalent Sb atoms to form RbMg10Sb2 cuboctahedra that share corners with four equivalent SbRb2Mg10 cuboctahedra, corners with six equivalent RbMg10Sb2 cuboctahedra, corners with eight equivalent MgRb2Mg8Sb2 cuboctahedra, edges with two equivalent SbRb2Mg10 cuboctahedra, edges with four equivalent MgRb2Mg8Sb2 cuboctahedra, faces with two equivalent RbMg10Sb2 cuboctahedra, faces with two equivalent SbRb2Mg10 cuboctahedra, and faces with four equivalent MgRb2Mg8Sb2 cuboctahedra. There are a spread of Rb–Mg bond distances ranging from 3.37–3.49 Å. Both Rb–Sb bond lengths are 3.38 Å. There are four inequivalent Mg sites. In the first Mg site, Mg is bonded to two equivalent Rb, eight Mg, and two equivalent Sb atoms to form distorted MgRb2Mg8Sb2 cuboctahedra that share corners with four equivalent RbMg10Sb2 cuboctahedra, corners with four equivalent SbRb2Mg10 cuboctahedra, corners with ten equivalent MgRb2Mg8Sb2 cuboctahedra, edges with two equivalent RbMg10Sb2 cuboctahedra, edges with two equivalent MgRb2Mg8Sb2 cuboctahedra, edges with two equivalent SbRb2Mg10 cuboctahedra, faces with two equivalent RbMg10Sb2 cuboctahedra, faces with two equivalent SbRb2Mg10 cuboctahedra, and faces with four equivalent MgRb2Mg8Sb2 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.26–3.42 Å. There are one shorter (3.41 Å) and one longer (3.53 Å) Mg–Sb bond lengths. In the second Mg site, Mg is bonded in a 4-coordinate geometry to two equivalent Rb, three Mg, and two equivalent Sb atoms. The Mg–Mg bond length is 3.26 Å. Both Mg–Sb bond lengths are 3.26 Å. In the third Mg site, Mg is bonded in a 2-coordinate geometry to two equivalent Rb and eight Mg atoms. Both Mg–Mg bond lengths are 3.39 Å. In the fourth Mg site, Mg is bonded in a distorted water-like geometry to six Mg and two equivalent Sb atoms. Both Mg–Sb bond lengths are 3.38 Å. Sb is bonded to two equivalent Rb and ten Mg atoms to form distorted SbRb2Mg10 cuboctahedra that share corners with four equivalent RbMg10Sb2 cuboctahedra, corners with six equivalent SbRb2Mg10 cuboctahedra, corners with eight equivalent MgRb2Mg8Sb2 cuboctahedra, edges with two equivalent RbMg10Sb2 cuboctahedra, edges with four equivalent MgRb2Mg8Sb2 cuboctahedra, faces with two equivalent RbMg10Sb2 cuboctahedra, faces with two equivalent SbRb2Mg10 cuboctahedra, and faces with four equivalent MgRb2Mg8Sb2 cuboctahedra.