Materials Data on KMg14Si by Materials Project

Abstract

KMg14Si crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. K is bonded to ten Mg and two equivalent Si atoms to form distorted KMg10Si2 cuboctahedra that share corners with six equivalent KMg10Si2 cuboctahedra, corners with twelve MgMg12 cuboctahedra, and faces with two equivalent MgMg12 cuboctahedra. There are a spread of K–Mg bond distances ranging from 3.30–3.44 Å. Both K–Si bond lengths are 3.17 Å. There are seven inequivalent Mg sites. In the first Mg site, Mg is bonded to twelve Mg atoms to form distorted MgMg12 cuboctahedra that share corners with six equivalent MgMg12 cuboctahedra, edges with six MgMg12 cuboctahedra, faces with two equivalent KMg10Si2 cuboctahedra, and faces with six MgMg12 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.09–3.48 Å. In the second Mg site, Mg is bonded to twelve Mg atoms to form distorted MgMg12 cuboctahedra that share corners with four equivalent KMg10Si2 cuboctahedra, corners with six equivalent MgMg12 cuboctahedra, edges with six MgMg12 cuboctahedra, and faces with six MgMg12 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.15–3.45 Å. In the third Mg site, Mg is bonded in a 1-coordinate geometry to two equivalent K, four Mg, and one Si atom. There are two shorter (3.12 Å) and two longer (3.31 Å) Mg–Mg bond lengths. The Mg–Si bond length is 2.81 Å. In the fourth Mg site, Mg is bonded to twelve Mg atoms to form distorted MgMg12 cuboctahedra that share corners with four equivalent KMg10Si2 cuboctahedra, corners with six equivalent MgMg12 cuboctahedra, edges with six MgMg12 cuboctahedra, and faces with six MgMg12 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.03–3.42 Å. In the fifth Mg site, Mg is bonded in a 1-coordinate geometry to one K, eight Mg, and one Si atom. There are a spread of Mg–Mg bond distances ranging from 2.98–3.31 Å. The Mg–Si bond length is 3.06 Å. In the sixth Mg site, Mg is bonded in a 1-coordinate geometry to one K and nine Mg atoms. Both Mg–Mg bond lengths are 3.13 Å. In the seventh Mg site, Mg is bonded in a 12-coordinate geometry to seven Mg and one Si atom. The Mg–Si bond length is 3.27 Å. Si is bonded in a 10-coordinate geometry to two equivalent K and eight Mg atoms.