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13 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Phase stability in the Hf-N and Zr-N systems

Hf and Zr nitrides are promising compounds for many technologically important areas, including high-temperature structural applications, quantum computing, and solar and optical applications. Here, this article reports on a comprehensive first-principles statistical mechanics study of phase stability in the Hf-N and Zr-N binary systems. A high solubility of nitrogen in the hcp forms of Hf and Zr is predicted. The rocksalt forms of HfN and ZrN can also tolerate a high degree of off-stoichiometry through the introduction of nitrogen and metal vacancies. The Hf-N binary favors a family of stacking faulted parent crystal structures at intermediate nitrogen concentrations that host a unique form of short-range order among nitrogen interstitials and vacancies. These phases can accommodate some degree of configurational entropy and remain ordered to temperatures as high as 1200 K.

Monte Carlo methods↗
DOE OSTI2020

Materials Data on Hf3N4 by Materials Project

Hf3N4 crystallizes in the cubic I-43d space group. The structure is three-dimensional. Hf4+ is bonded in a 8-coordinate geometry to eight equivalent N3- atoms. There are four shorter (2.21 Å) and four longer (2.45 Å) Hf–N bond lengths. N3- is bonded in a 6-coordinate geometry to six equivalent Hf4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HfN by Materials Project

HfN is Halite, Rock Salt structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Hf is bonded to six equivalent N atoms to form a mixture of edge and corner-sharing HfN6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Hf–N bond lengths are 2.27 Å. N is bonded to six equivalent Hf atoms to form a mixture of edge and corner-sharing NHf6 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf4N3 by Materials Project

Hf4N3 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. there are two inequivalent Hf sites. In the first Hf site, Hf is bonded to five N atoms to form a mixture of edge and corner-sharing HfN5 square pyramids. There are one shorter (2.18 Å) and four longer (2.27 Å) Hf–N bond lengths. In the second Hf site, Hf is bonded in a square co-planar geometry to four N atoms. There are two shorter (2.27 Å) and two longer (2.28 Å) Hf–N bond lengths. There are two inequivalent N sites. In the first N site, N is bonded to six Hf atoms to form a mixture of edge and corner-sharing NHf6 octahedra. The corner-sharing octahedral tilt angles are 0°. In the second N site, N is bonded to six Hf atoms to form a mixture of edge and corner-sharing NHf6 octahedra. The corner-sharing octahedra tilt angles range from 0–5°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HfN by Materials Project

HfN is Tetraauricupride structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Hf is bonded in a body-centered cubic geometry to eight equivalent N atoms. All Hf–N bond lengths are 2.44 Å. N is bonded in a body-centered cubic geometry to eight equivalent Hf atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HfN by Materials Project

HfN is Zincblende, Sphalerite structured and crystallizes in the cubic F-43m space group. The structure is three-dimensional. Hf is bonded to four equivalent N atoms to form corner-sharing HfN4 tetrahedra. All Hf–N bond lengths are 2.13 Å. N is bonded to four equivalent Hf atoms to form corner-sharing NHf4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf3N4 by Materials Project

Hf3N4 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 in a 7-coordinate geometry to seven N3- atoms. There are a spread of Hf–N bond distances ranging from 2.04–2.59 Å. In the second Hf4+ site, Hf4+ is bonded to six equivalent N3- atoms to form edge-sharing HfN6 octahedra. All Hf–N bond lengths are 2.27 Å. There are two inequivalent N3- sites. In the first N3- site, N3- is bonded to six Hf4+ atoms to form distorted NHf6 octahedra that share corners with three equivalent NHf6 octahedra, corners with six equivalent NHf4 tetrahedra, edges with nine equivalent NHf6 octahedra, and edges with three equivalent NHf4 tetrahedra. The corner-sharing octahedral tilt angles are 0°. In the second N3- site, N3- is bonded to four equivalent Hf4+ atoms to form NHf4 tetrahedra that share corners with six equivalent NHf6 octahedra, corners with six equivalent NHf4 tetrahedra, edges with three equivalent NHf6 octahedra, and edges with three equivalent NHf4 tetrahedra. The corner-sharing octahedra tilt angles range from 25–50°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf3N4 by Materials Project

Hf3N4 is Hausmannite structured and crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. there are two inequivalent Hf4+ sites. In the first Hf4+ site, Hf4+ is bonded to six equivalent N3- atoms to form HfN6 octahedra that share corners with six equivalent HfN4 tetrahedra and edges with six equivalent HfN6 octahedra. All Hf–N bond lengths are 2.20 Å. In the second Hf4+ site, Hf4+ is bonded to four equivalent N3- atoms to form corner-sharing HfN4 tetrahedra. The corner-sharing octahedral tilt angles are 57°. All Hf–N bond lengths are 2.09 Å. N3- is bonded in a distorted rectangular see-saw-like geometry to four Hf4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf2N by Materials Project

Hf2N is Rutile structured and crystallizes in the tetragonal P4_2/mnm space group. The structure is three-dimensional. Hf is bonded in a distorted T-shaped geometry to three equivalent N atoms. There are one shorter (2.23 Å) and two longer (2.25 Å) Hf–N bond lengths. N is bonded to six equivalent Hf atoms to form a mixture of edge and corner-sharing NHf6 octahedra. The corner-sharing octahedral tilt angles are 46°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HfN2 by Materials Project

HfN2 crystallizes in the hexagonal P-6m2 space group. The structure is three-dimensional. Hf4+ is bonded in a 6-coordinate geometry to six equivalent N2- atoms. All Hf–N bond lengths are 2.23 Å. N2- is bonded in a 4-coordinate geometry to three equivalent Hf4+ and one N2- atom. The N–N bond length is 1.44 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HfN2 by Materials Project

HfN2 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Hf4+ is bonded in a 6-coordinate geometry to six equivalent N2- atoms. All Hf–N bond lengths are 2.22 Å. N2- is bonded in a 4-coordinate geometry to three equivalent Hf4+ and one N2- atom. The N–N bond length is 1.43 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf3N2 by Materials Project

Hf3N2 is MAX Phase-derived structured and crystallizes in the trigonal R-3m space group. The structure is two-dimensional and consists of three Hf3N2 sheets oriented in the (0, 0, 1) direction. there are two inequivalent Hf sites. In the first Hf site, Hf is bonded in a distorted T-shaped geometry to three equivalent N atoms. All Hf–N bond lengths are 2.29 Å. In the second Hf site, Hf is bonded to six equivalent N atoms to form edge-sharing HfN6 octahedra. All Hf–N bond lengths are 2.26 Å. N is bonded to six Hf atoms to form a mixture of edge and corner-sharing NHf6 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf3N2 by Materials Project

Hf3N2 crystallizes in the trigonal R3m space group. The structure is two-dimensional and consists of three Hf3N2 sheets oriented in the (0, 0, 1) direction. there are three inequivalent Hf sites. In the first Hf site, Hf is bonded in a distorted T-shaped geometry to three equivalent N atoms. All Hf–N bond lengths are 2.26 Å. In the second Hf site, Hf is bonded to six N atoms to form distorted edge-sharing HfN6 pentagonal pyramids. There are three shorter (2.28 Å) and three longer (2.32 Å) Hf–N bond lengths. In the third Hf site, Hf is bonded in a distorted T-shaped geometry to three equivalent N atoms. All Hf–N bond lengths are 2.24 Å. There are two inequivalent N sites. In the first N site, N is bonded to six Hf atoms to form a mixture of face, edge, and corner-sharing NHf6 octahedra. The corner-sharing octahedral tilt angles are 47°. In the second N site, N is bonded to six Hf atoms to form a mixture of face, edge, and corner-sharing NHf6 octahedra. The corner-sharing octahedral tilt angles are 47°.

36 MATERIALS SCIENCE↗