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5 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Hf2Al3C4 by Materials Project

Hf2Al3C4 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Hf is bonded to six C atoms to form HfC6 octahedra that share corners with three equivalent HfC6 octahedra, corners with three equivalent AlC4 tetrahedra, edges with nine equivalent HfC6 octahedra, and edges with three equivalent AlC4 tetrahedra. The corner-sharing octahedral tilt angles are 0°. There are three shorter (2.31 Å) and three longer (2.46 Å) Hf–C bond lengths. There are two inequivalent Al sites. In the first Al site, Al is bonded to four C atoms to form AlC4 tetrahedra that share corners with three equivalent HfC6 octahedra, corners with seven equivalent AlC4 tetrahedra, and edges with three equivalent HfC6 octahedra. The corner-sharing octahedral tilt angles are 18°. There are one shorter (2.03 Å) and three longer (2.05 Å) Al–C bond lengths. In the second Al site, Al is bonded in a trigonal planar geometry to three equivalent C atoms. All Al–C bond lengths are 1.93 Å. There are three inequivalent C sites. In the first C site, C is bonded to three equivalent Hf and three equivalent Al atoms to form distorted CHf3Al3 octahedra that share corners with three equivalent CHf6 octahedra, corners with three equivalent CAl5 trigonal bipyramids, and edges with nine CHf3Al3 octahedra. The corner-sharing octahedral tilt angles are 5°. In the second C site, C is bonded to five Al atoms to form CAl5 trigonal bipyramids that share corners with six equivalent CHf3Al3 octahedra and corners with six equivalent CAl5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 70°. In the third C site, C is bonded to six equivalent Hf atoms to form a mixture of edge and corner-sharing CHf6 octahedra. The corner-sharing octahedral tilt angles are 5°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf2Al4C5 by Materials Project

Hf2Al4C5 crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Hf4+ is bonded to six C4- atoms to form HfC6 octahedra that share corners with three equivalent HfC6 octahedra, corners with three equivalent AlC4 tetrahedra, edges with nine equivalent HfC6 octahedra, and edges with three equivalent AlC4 tetrahedra. The corner-sharing octahedral tilt angles are 0°. There are three shorter (2.34 Å) and three longer (2.36 Å) Hf–C bond lengths. There are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to four C4- atoms to form AlC4 tetrahedra that share corners with three equivalent HfC6 octahedra, corners with six equivalent AlC4 tetrahedra, corners with four equivalent AlC4 trigonal pyramids, and edges with three equivalent HfC6 octahedra. The corner-sharing octahedral tilt angles are 10°. There are one shorter (1.94 Å) and three longer (2.14 Å) Al–C bond lengths. In the second Al3+ site, Al3+ is bonded to four equivalent C4- atoms to form a mixture of edge and corner-sharing AlC4 trigonal pyramids. There are three shorter (1.95 Å) and one longer (2.18 Å) Al–C bond lengths. There are three inequivalent C4- sites. In the first C4- site, C4- is bonded to three equivalent Hf4+ and three equivalent Al3+ atoms to form CHf3Al3 octahedra that share corners with three equivalent CHf6 octahedra, corners with three equivalent CAl5 trigonal bipyramids, and edges with nine CHf3Al3 octahedra. The corner-sharing octahedral tilt angles are 1°. In the second C4- site, C4- is bonded to six equivalent Hf4+ atoms to form a mixture of edge and corner-sharing CHf6 octahedra. The corner-sharing octahedral tilt angles are 1°. In the third C4- site, C4- is bonded to five Al3+ atoms to form CAl5 trigonal bipyramids that share corners with three equivalent CHf3Al3 octahedra, corners with six equivalent CAl5 trigonal bipyramids, and edges with three equivalent CAl5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 64°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf3(Al2C3)2 by Materials Project

Hf3Al4C6 crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are two inequivalent Hf4+ sites. In the first Hf4+ site, Hf4+ is bonded to six C4- atoms to form HfC6 octahedra that share corners with three equivalent HfC6 octahedra, corners with three equivalent AlC4 tetrahedra, edges with nine HfC6 octahedra, and edges with three equivalent AlC4 tetrahedra. The corner-sharing octahedral tilt angles are 1°. There are three shorter (2.33 Å) and three longer (2.37 Å) Hf–C bond lengths. In the second Hf4+ site, Hf4+ is bonded to six equivalent C4- atoms to form a mixture of corner and edge-sharing HfC6 octahedra. The corner-sharing octahedral tilt angles are 1°. All Hf–C bond lengths are 2.34 Å. There are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to four C4- atoms to form AlC4 tetrahedra that share corners with three equivalent HfC6 octahedra, corners with six equivalent AlC4 tetrahedra, corners with four equivalent AlC4 trigonal pyramids, and edges with three equivalent HfC6 octahedra. The corner-sharing octahedral tilt angles are 10°. There are one shorter (1.95 Å) and three longer (2.13 Å) Al–C bond lengths. In the second Al3+ site, Al3+ is bonded to four equivalent C4- atoms to form a mixture of distorted corner and edge-sharing AlC4 trigonal pyramids. There are three shorter (1.95 Å) and one longer (2.19 Å) Al–C bond lengths. There are three inequivalent C4- sites. In the first C4- site, C4- is bonded to six Hf4+ atoms to form a mixture of corner and edge-sharing CHf6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. In the second C4- site, C4- is bonded to five Al3+ atoms to form CAl5 trigonal bipyramids that share corners with three equivalent CHf3Al3 octahedra, corners with six equivalent CAl5 trigonal bipyramids, and edges with three equivalent CAl5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 65°. In the third C4- site, C4- is bonded to three equivalent Hf4+ and three equivalent Al3+ atoms to form CHf3Al3 octahedra that share corners with three equivalent CHf6 octahedra, corners with three equivalent CAl5 trigonal bipyramids, and edges with nine CHf6 octahedra. The corner-sharing octahedral tilt angles are 1°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf5Al3C by Materials Project

Hf5Al3C crystallizes in the hexagonal P6_3/mcm space group. The structure is three-dimensional. there are two inequivalent Hf sites. In the first Hf site, Hf is bonded in a 2-coordinate geometry to five equivalent Al and two equivalent C atoms. There are a spread of Hf–Al bond distances ranging from 2.85–3.20 Å. Both Hf–C bond lengths are 2.32 Å. In the second Hf site, Hf is bonded in a 6-coordinate geometry to two equivalent Hf and six equivalent Al atoms. Both Hf–Hf bond lengths are 2.84 Å. All Hf–Al bond lengths are 2.86 Å. Al is bonded in a 9-coordinate geometry to nine Hf atoms. C is bonded to six equivalent Hf atoms to form face-sharing CHf6 octahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

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°.

36 MATERIALS SCIENCE↗