Materials Data on Mg2Al2Se5 by Materials Project

Abstract

Mg2Al2Se5 crystallizes in the trigonal P-3m1 space group. The structure is two-dimensional and consists of one Mg2Al2Se5 sheet oriented in the (0, 0, 1) direction. Mg2+ is bonded to six Se2- atoms to form MgSe6 octahedra that share corners with three equivalent MgSe6 octahedra, corners with three equivalent AlSe4 tetrahedra, and edges with nine equivalent MgSe6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are three shorter (2.67 Å) and three longer (2.78 Å) Mg–Se bond lengths. Al3+ is bonded to four Se2- atoms to form AlSe4 tetrahedra that share corners with three equivalent MgSe6 octahedra and corners with six equivalent AlSe4 tetrahedra. The corner-sharing octahedral tilt angles are 58°. There are one shorter (2.31 Å) and three longer (2.50 Å) Al–Se bond lengths. There are three inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a trigonal non-coplanar geometry to three equivalent Al3+ atoms. In the second Se2- site, Se2- is bonded to three equivalent Mg2+ and one Al3+ atom to form distorted SeMg3Al trigonal pyramids that share corners with three equivalent SeMg6 octahedra, corners with six equivalent SeMg3Al trigonal pyramids, and edges with three equivalent SeMg6 octahedra. The corner-sharing octahedral tilt angles are 3°. In the third Se2- site, Se2- is bonded to six equivalent Mg2+ atoms to form SeMg6 octahedra that share corners with six equivalent SeMg3Al trigonal pyramids, edges with six equivalent SeMg6 octahedra, and edges with six equivalent SeMg3Al trigonal pyramids.