Materials Data on Zr2Al3C4 by Materials Project

Abstract

Zr2Al3C4 crystallizes in the hexagonal P6_3mc space group. The structure is two-dimensional and consists of two aluminum molecules and two AlZrC2 sheets oriented in the (0, 0, 1) direction. In each AlZrC2 sheet, there are two inequivalent Zr+3.50+ sites. In the first Zr+3.50+ site, Zr+3.50+ is bonded to six C4- atoms to form ZrC6 octahedra that share corners with three equivalent AlC6 octahedra, edges with three equivalent AlC6 octahedra, and edges with six equivalent ZrC6 octahedra. The corner-sharing octahedral tilt angles are 8°. There are three shorter (2.33 Å) and three longer (2.37 Å) Zr–C bond lengths. In the second Zr+3.50+ site, Zr+3.50+ is bonded in a distorted T-shaped geometry to three equivalent C4- atoms. All Zr–C bond lengths are 2.25 Å. There are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to six C4- atoms to form AlC6 octahedra that share corners with three equivalent ZrC6 octahedra, corners with three equivalent CAl3C tetrahedra, edges with three equivalent ZrC6 octahedra, and edges with six equivalent AlC6 octahedra. The corner-sharing octahedral tilt angles are 8°. There are three shorter (2.13 Å) and three longer (2.34 Å) Al–C bond lengths. In the second Al3+ site, Al3+ is bonded in a trigonal non-coplanar geometry to three equivalent C4- atoms. All Al–C bond lengths are 2.09 Å. There are four inequivalent C4- sites. In the first C4- site, C4- is bonded to three equivalent Al3+ and one C4- atom to form CAl3C tetrahedra that share corners with three equivalent AlC6 octahedra and corners with six equivalent CAl3C tetrahedra. The corner-sharing octahedral tilt angles are 53°. The C–C bond length is 1.31 Å. In the second C4- site, C4- is bonded to three equivalent Zr+3.50+ and three equivalent Al3+ atoms to form CZr3Al3 octahedra that share corners with three equivalent CZr6 octahedra and edges with nine CZr3Al3 octahedra. The corner-sharing octahedral tilt angles are 1°. In the third C4- site, C4- is bonded to six Zr+3.50+ atoms to form a mixture of edge and corner-sharing CZr6 octahedra. The corner-sharing octahedral tilt angles are 1°. In the fourth C4- site, C4- is bonded in a rectangular see-saw-like geometry to three equivalent Al3+ and one C4- atom.