DOI: 10.17188/1274868
title: Materials Data on Mg2Co12As7 by Materials Project

description: Mg2Co12As7 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six As3- atoms to form distorted MgAs6 pentagonal pyramids that share corners with twelve CoAs4 tetrahedra, corners with six CoAs5 trigonal bipyramids, edges with ten CoAs4 tetrahedra, edges with two CoAs5 trigonal bipyramids, and faces with two equivalent MgAs6 pentagonal pyramids. There are a spread of Mg–As bond distances ranging from 2.81–2.91 Å. In the second Mg2+ site, Mg2+ is bonded to six As3- atoms to form distorted MgAs6 pentagonal pyramids that share corners with twelve CoAs4 tetrahedra, corners with six CoAs5 trigonal bipyramids, edges with nine CoAs4 tetrahedra, edges with three CoAs5 trigonal bipyramids, and faces with two equivalent MgAs6 pentagonal pyramids. There are a spread of Mg–As bond distances ranging from 2.84–2.87 Å. There are twelve inequivalent Co+1.42+ sites. In the first Co+1.42+ site, Co+1.42+ is bonded to four As3- atoms to form CoAs4 tetrahedra that share corners with two equivalent MgAs6 pentagonal pyramids, corners with nine CoAs4 tetrahedra, corners with five CoAs5 trigonal bipyramids, edges with three MgAs6 pentagonal pyramids, edges with four CoAs4 tetrahedra, and an edgeedge with one CoAs5 trigonal bipyramid. There are a spread of Co–As bond distances ranging from 2.31–2.41 Å. In the second Co+1.42+ site, Co+1.42+ is bonded to four As3- atoms to form CoAs4 tetrahedra that share corners with two equivalent MgAs6 pentagonal pyramids, corners with twelve CoAs4 tetrahedra, corners with two equivalent CoAs5 trigonal bipyramids, edges with three MgAs6 pentagonal pyramids, edges with three CoAs4 tetrahedra, and edges with two equivalent CoAs5 trigonal bipyramids. There are a spread of Co–As bond distances ranging from 2.29–2.38 Å. In the third Co+1.42+ site, Co+1.42+ is bonded to four As3- atoms to form CoAs4 tetrahedra that share corners with two equivalent MgAs6 pentagonal pyramids, corners with twelve CoAs4 tetrahedra, corners with two equivalent CoAs5 trigonal bipyramids, edges with three MgAs6 pentagonal pyramids, edges with three CoAs4 tetrahedra, and edges with two equivalent CoAs5 trigonal bipyramids. There are a spread of Co–As bond distances ranging from 2.26–2.36 Å. In the fourth Co+1.42+ site, Co+1.42+ is bonded to four As3- atoms to form CoAs4 tetrahedra that share corners with two equivalent MgAs6 pentagonal pyramids, corners with nine CoAs4 tetrahedra, corners with five CoAs5 trigonal bipyramids, edges with three MgAs6 pentagonal pyramids, edges with four CoAs4 tetrahedra, and an edgeedge with one CoAs5 trigonal bipyramid. There are a spread of Co–As bond distances ranging from 2.30–2.42 Å. In the fifth Co+1.42+ site, Co+1.42+ is bonded to five As3- atoms to form distorted CoAs5 trigonal bipyramids that share corners with six MgAs6 pentagonal pyramids, corners with ten CoAs4 tetrahedra, edges with two equivalent MgAs6 pentagonal pyramids, edges with eight CoAs4 tetrahedra, and edges with two equivalent CoAs5 trigonal bipyramids. There are a spread of Co–As bond distances ranging from 2.34–2.59 Å. In the sixth Co+1.42+ site, Co+1.42+ is bonded to four As3- atoms to form CoAs4 tetrahedra that share corners with four MgAs6 pentagonal pyramids, corners with eight CoAs4 tetrahedra, corners with four CoAs5 trigonal bipyramids, an edgeedge with one MgAs6 pentagonal pyramid, edges with four CoAs4 tetrahedra, and edges with three CoAs5 trigonal bipyramids. There are two shorter (2.30 Å) and two longer (2.32 Å) Co–As bond lengths. In the seventh Co+1.42+ site, Co+1.42+ is bonded to five As3- atoms to form distorted CoAs5 trigonal bipyramids that share corners with four MgAs6 pentagonal pyramids, corners with nine CoAs4 tetrahedra, corners with three equivalent CoAs5 trigonal bipyramids, edges with two MgAs6 pentagonal pyramids, edges with eight CoAs4 tetrahedra, and edges with two equivalent CoAs5 trigonal bipyramids. There are a spread of Co–As bond distances ranging from 2.41–2.59 Å. In the eighth Co+1.42+ site, Co+1.42+ is bonded to four As3- atoms to form CoAs4 tetrahedra that share corners with ten CoAs4 tetrahedra, corners with six CoAs5 trigonal bipyramids, edges with two equivalent MgAs6 pentagonal pyramids, edges with three CoAs4 tetrahedra, and edges with three CoAs5 trigonal bipyramids. There are a spread of Co–As bond distances ranging from 2.27–2.42 Å. In the ninth Co+1.42+ site, Co+1.42+ is bonded to five As3- atoms to form distorted CoAs5 trigonal bipyramids that share corners with two equivalent MgAs6 pentagonal pyramids, corners with eleven CoAs4 tetrahedra, corners with three equivalent CoAs5 trigonal bipyramids, an edgeedge with one MgAs6 pentagonal pyramid, edges with seven CoAs4 tetrahedra, and edges with four equivalent CoAs5 trigonal bipyramids. There are a spread of Co–As bond distances ranging from 2.40–2.66 Å. In the tenth Co+1.42+ site, Co+1.42+ is bonded to four As3- atoms to form CoAs4 tetrahedra that share corners with six MgAs6 pentagonal pyramids, corners with eight CoAs4 tetrahedra, corners with two equivalent CoAs5 trigonal bipyramids, an edgeedge with one MgAs6 pentagonal pyramid, edges with four CoAs4 tetrahedra, and edges with three CoAs5 trigonal bipyramids. There are a spread of Co–As bond distances ranging from 2.30–2.32 Å. In the eleventh Co+1.42+ site, Co+1.42+ is bonded to four As3- atoms to form CoAs4 tetrahedra that share corners with fourteen CoAs4 tetrahedra, corners with two equivalent CoAs5 trigonal bipyramids, edges with two equivalent MgAs6 pentagonal pyramids, an edgeedge with one CoAs4 tetrahedra, and edges with five CoAs5 trigonal bipyramids. There are a spread of Co–As bond distances ranging from 2.25–2.33 Å. In the twelfth Co+1.42+ site, Co+1.42+ is bonded to four As3- atoms to form CoAs4 tetrahedra that share corners with six MgAs6 pentagonal pyramids, corners with eight CoAs4 tetrahedra, corners with two equivalent CoAs5 trigonal bipyramids, an edgeedge with one MgAs6 pentagonal pyramid, edges with four CoAs4 tetrahedra, and edges with three equivalent CoAs5 trigonal bipyramids. There are a spread of Co–As bond distances ranging from 2.30–2.33 Å. There are seven inequivalent As3- sites. In the first As3- site, As3- is bonded in a 9-coordinate geometry to two equivalent Mg2+ and seven Co+1.42+ atoms. In the second As3- site, As3- is bonded in a 9-coordinate geometry to two equivalent Mg2+ and seven Co+1.42+ atoms. In the third As3- site, As3- is bonded in a 9-coordinate geometry to nine Co+1.42+ atoms. In the fourth As3- site, As3- is bonded in a 9-coordinate geometry to two equivalent Mg2+ and seven Co+1.42+ atoms. In the fifth As3- site, As3- is bonded in a 9-coordinate geometry to two equivalent Mg2+ and seven Co+1.42+ atoms. In the sixth As3- site, As3- is bonded in a 9-coordinate geometry to two equivalent Mg2+ and seven Co+1.42+ atoms. In the seventh As3- site, As3- is bonded in a 9-coordinate geometry to two equivalent Mg2+ and seven Co+1.42+ atoms.