Materials Data on Hf2Al3C5 by Materials Project
Hf2Al3C5 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Hf4+ is bonded to six C+3.40- atoms to form HfC6 octahedra that share corners with three equivalent HfC6 octahedra, corners with three equivalent AlC6 octahedra, edges with three equivalent AlC6 octahedra, and edges with nine equivalent HfC6 octahedra. The corner-sharing octahedra tilt angles range from 0–8°. All Hf–C bond lengths are 2.31 Å. There are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to six C+3.40- atoms to form AlC6 octahedra that share corners with three equivalent HfC6 octahedra, edges with three equivalent HfC6 octahedra, and edges with six equivalent AlC6 octahedra. The corner-sharing octahedral tilt angles are 8°. There are three shorter (2.11 Å) and three longer (2.40 Å) Al–C bond lengths. In the second Al3+ site, Al3+ is bonded in a 6-coordinate geometry to six equivalent C+3.40- atoms. All Al–C bond lengths are 2.03 Å. There are three inequivalent C+3.40- sites. In the first C+3.40- site, C+3.40- is bonded in a 7-coordinate geometry to six Al3+ and one C+3.40- atom. The C–C bond length is 1.64 Å. In the second C+3.40- site, C+3.40- is bonded to three equivalent Hf4+ and three equivalent Al3+ atoms to form a mixture of corner and edge-sharing CHf3Al3 octahedra. The corner-sharing octahedral tilt angles are 0°. In the third C+3.40- site, C+3.40- is bonded to six equivalent Hf4+ atoms to form CHf6 octahedra that share corners with six equivalent CHf3Al3 octahedra and edges with twelve CHf6 octahedra. The corner-sharing octahedral tilt angles are 0°.