Materials Data on Eu3(AlAs2)2 by Materials Project

Abstract

Eu3Al2As4 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. there are two inequivalent Eu2+ sites. In the first Eu2+ site, Eu2+ is bonded to six As3- atoms to form distorted EuAs6 octahedra that share corners with seven EuAs6 octahedra, corners with six equivalent AlAs4 tetrahedra, edges with six equivalent EuAs6 octahedra, edges with three equivalent AlAs4 tetrahedra, and a faceface with one EuAs6 octahedra. The corner-sharing octahedra tilt angles range from 16–60°. There are a spread of Eu–As bond distances ranging from 3.02–3.48 Å. In the second Eu2+ site, Eu2+ is bonded to six As3- atoms to form EuAs6 octahedra that share corners with ten equivalent EuAs6 octahedra, corners with four equivalent AlAs4 tetrahedra, edges with two equivalent EuAs6 octahedra, edges with four equivalent AlAs4 tetrahedra, and faces with two equivalent EuAs6 octahedra. The corner-sharing octahedra tilt angles range from 34–60°. There are a spread of Eu–As bond distances ranging from 3.02–3.18 Å. Al3+ is bonded to four As3- atoms to form AlAs4 tetrahedra that share corners with eight EuAs6 octahedra, corners with two equivalent AlAs4 tetrahedra, edges with five EuAs6 octahedra, and an edgeedge with one AlAs4 tetrahedra. The corner-sharing octahedra tilt angles range from 20–84°. There are a spread of Al–As bond distances ranging from 2.48–2.54 Å. There are two inequivalent As3- sites. In the first As3- site, As3- is bonded in a 7-coordinate geometry to five Eu2+ and two equivalent Al3+ atoms. In the second As3- site, As3- is bonded in a 6-coordinate geometry to four Eu2+ and two equivalent Al3+ atoms.