HfN2
HfN2 is a semiconducting hafnium nitride compound that exists as a complex, metastable phase within the ultra-high-temperature ceramic class.
About HfN2
HfN2 is a semiconducting member of the ultra-high-temperature ceramic family, composed of hafnium and nitrogen. Despite the extensive interest in hafnium-based nitrides, this specific stoichiometry represents a complex phase that sits above the thermodynamic hull, suggesting it is a metastable or challenging material to synthesize in bulk form.
Its significance lies in the vast structural diversity associated with the Hf-N system, with hundreds of reported configurations across various databases. Research into this compound contributes to the broader understanding of how transition metal nitrides behave under extreme conditions and their potential for specialized electronic or structural applications.
Key Properties
Cross-validated computational properties for HfN2, aggregated across 4 databases.
Band GapEnergy needed to move an electron from the valence band to the conduction band. Lower or zero values tend to behave more metallic; larger gaps are more insulating or semiconducting.
Energy Above HullThermodynamic distance from the most stable set of competing phases. 0 eV/atom is on the convex hull; small positive values may still be experimentally accessible.
StabilityA plain-language summary of the best reported energy-above-hull result. It reflects whether the lowest-energy structure is on, near, or far from the stability hull.
StructuresCount of reported calculated crystal structures for this formula, including alternate polymorphs, source databases, and observed space groups.
Cross-Source DFT Agreement
How well independent DFT databases agree on the thermodynamics of HfN2. Tight agreement means computed properties can be trusted without re-running calculations.
Agreement ScoreA normalized confidence score summarizing how closely independent DFT databases agree. Higher scores mean tighter cross-source agreement.
Hull SpreadDifference between the highest and lowest energy-above-hull values reported by comparable sources. Smaller spread means less thermodynamic disagreement.
Sources ComparedNumber and names of computational sources with comparable entries for this formula.
Space Group ConsensusWhether independent sources predict the same crystal symmetry for the lowest-energy structure.
Reported Structures
Lowest-energy structures reported for HfN2, ranked by energy above hull.
| Space GroupSymmetry classification of the crystal arrangement. The number is the international space-group index. | Crystal SystemBroad lattice family, such as cubic, tetragonal, monoclinic, or triclinic, derived from unit-cell symmetry. | Band Gap (eV)Electronic gap calculated for this specific reported structure, measured in electronvolts. | E above hull (eV/atom)Thermodynamic distance from the convex hull for this structure, normalized per atom. Lower is generally more stable. | E/atom (eV)Computed total energy normalized per atom. Use energy above hull, not this value alone, when comparing stability. | Density (g/cm³)Mass per relaxed crystal volume, reported in grams per cubic centimeter. |
|---|---|---|---|---|---|
| Pa-3 (No. 205) | cubic | 1.19 | 0.4150 | -22.257 | 10.17 |
| P63/mmc (No. 194) | hexagonal | 0.58 | 0.4569 | -22.215 | 9.81 |
| P-6m2 (No. 187) | hexagonal | 0.00 | 0.5010 | -22.171 | 9.77 |
| P63/mmc (No. 194) | hexagonal | 0.64 | 0.5395 | -0.917 | — |
| P-6m2 (No. 187) | hexagonal | 0.00 | 0.5831 | -0.873 | — |
| — | — | 0.00 | 1.4238 | 0.088 | — |
| — | — | 0.00 | 2.8105 | 1.475 | — |
| P1 (No. 1) | triclinic | — | — | — | 11.15 |
| P1 (No. 1) | triclinic | — | — | — | 8.67 |
| P1 (No. 1) | triclinic | — | — | — | 12.86 |
| P1 (No. 1) | triclinic | — | — | — | 8.29 |
| P1 (No. 1) | triclinic | — | — | — | 6.04 |
Applications
Where HfN2 is used.
Frequently Asked Questions
Common questions about HfN2, answered from cross-validated data.
What is HfN2?
HfN2 is a semiconducting hafnium nitride compound that exists as a complex, metastable phase within the ultra-high-temperature ceramic class.
What is HfN2 used for?
What is the band gap of HfN2?
Is HfN2 a metal, semiconductor, or insulator?
Is HfN2 thermodynamically stable?
What is the crystal structure of HfN2?
What is the density of HfN2?
How many polymorphs of HfN2 are known?
What elements does HfN2 contain?
Where does the data for HfN2 come from?
How It Compares
Within the ultra-high-temperature ceramics class.
Unlike the highly stable and widely utilized HfC or the more common Hf3N4, HfN2 occupies a less favorable thermodynamic position, making it a more elusive member of the ultra-high-temperature ceramic class. While its siblings are often characterized by their robust refractory nature, HfN2 is distinguished by its semiconducting electronic character, which sets it apart from the metallic or insulating behaviors typically seen in related carbides and nitrides like ZrC or TaN.
Related Compounds
Other Ultra-High-Temperature Ceramics in the database.
Data sources & attribution
- materials_project — Data from the Materials Project (materialsproject.org). Cite: Jain et al., APL Materials 1, 011002 (2013). (CC-BY-4.0)
- jarvis — Data from JARVIS (jarvis.nist.gov), NIST. Cite: Choudhary et al., npj Comp. Mater. 6, 173 (2020). (LicenseRef-US-Gov-PD)
- oqmd — Data from the OQMD (oqmd.org). Cite: Saal et al., JOM 65, 1501 (2013); Kirklin et al., npj Comp. Mater. 1, 15010 (2015). (CC-BY-4.0)
- mpaloe — Data from MP-ALOE. Cite: Kuner et al., npj Comput. Mater. (2025), doi:10.1038/s41524-025-01834-9.
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