Materials Data on KMg6Nb by Materials Project

Abstract

KMg6Nb crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. K is bonded to twelve Mg atoms to form KMg12 cuboctahedra that share corners with four equivalent KMg12 cuboctahedra, corners with eight equivalent NbMg12 cuboctahedra, edges with eight equivalent MgK2Mg8Nb2 cuboctahedra, faces with two equivalent KMg12 cuboctahedra, faces with four equivalent MgK2Mg8Nb2 cuboctahedra, and faces with four equivalent NbMg12 cuboctahedra. There are a spread of K–Mg bond distances ranging from 3.27–3.50 Å. There are four inequivalent Mg sites. In the first Mg site, Mg is bonded to two equivalent K, eight Mg, and two equivalent Nb atoms to form distorted MgK2Mg8Nb2 cuboctahedra that share corners with twelve equivalent MgK2Mg8Nb2 cuboctahedra, edges with four equivalent KMg12 cuboctahedra, edges with four equivalent NbMg12 cuboctahedra, faces with two equivalent KMg12 cuboctahedra, faces with two equivalent NbMg12 cuboctahedra, and faces with six equivalent MgK2Mg8Nb2 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.23–3.30 Å. There are one shorter (3.25 Å) and one longer (3.31 Å) Mg–Nb bond lengths. In the second Mg site, Mg is bonded in a 10-coordinate geometry to two equivalent K, six Mg, and two equivalent Nb atoms. There are one shorter (2.87 Å) and one longer (2.90 Å) Mg–Mg bond lengths. Both Mg–Nb bond lengths are 3.06 Å. In the third Mg site, Mg is bonded in a 10-coordinate geometry to two equivalent K, six Mg, and two equivalent Nb atoms. Both Mg–Nb bond lengths are 3.07 Å. In the fourth Mg site, Mg is bonded in a 10-coordinate geometry to two equivalent K, six Mg, and two equivalent Nb atoms. Both Mg–Nb bond lengths are 3.09 Å. Nb is bonded to twelve Mg atoms to form NbMg12 cuboctahedra that share corners with four equivalent NbMg12 cuboctahedra, corners with eight equivalent KMg12 cuboctahedra, edges with eight equivalent MgK2Mg8Nb2 cuboctahedra, faces with two equivalent NbMg12 cuboctahedra, faces with four equivalent KMg12 cuboctahedra, and faces with four equivalent MgK2Mg8Nb2 cuboctahedra.