HN
HN is an insulating, hydrogen-rich compound classified as a hydride that is frequently studied for its structural diversity despite its inherent thermodynamic instability.
About HN
HN is a hydrogen-bearing compound categorized within the hydrogen storage hydrides class. Characterized by its wide-band-gap insulating electronic nature, this material represents a unique structural configuration of hydrogen and nitrogen atoms. Given its position above the thermodynamic hull, it is considered a metastable or unstable phase that requires careful synthesis and characterization.
Despite its instability, the compound is notable for its significant data richness, with hundreds of reported structures across various databases. This extensive documentation makes it a subject of interest for researchers investigating the fundamental limits of hydride stability and the potential for novel hydrogen-dense phases in high-pressure or specialized environments.
Key Properties
Cross-validated computational properties for HN, aggregated across 6 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 HN. 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 HN, 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. |
|---|---|---|---|---|---|
| — | — | 4.28 | 0.0915 | -0.158 | — |
| P21/c (No. 14) | monoclinic | 4.36 | 0.1478 | -6.377 | 1.36 |
| Pmna (No. 53) | orthorhombic | 4.16 | 0.1682 | -6.356 | 1.40 |
| P-1 (No. 2) | triclinic | 2.87 | 0.1924 | -6.332 | 1.27 |
| — | — | 4.40 | 0.1963 | -0.053 | — |
| — | — | 4.34 | 0.1964 | -0.053 | — |
| P-1 (No. 2) | triclinic | 6.82 | 0.2142 | 0.015 | — |
| P-1 (No. 2) | triclinic | 1.81 | 0.3056 | -6.219 | 1.78 |
| P-1 (No. 2) | triclinic | 2.62 | 0.3805 | 0.182 | — |
| P-6m2 (No. 187) | hexagonal | 0.00 | 1.7353 | 1.537 | — |
| P4mm (No. 99) | tetragonal | 3.31 | 2.1072 | 1.908 | — |
| — | — | 0.00 | 2.2547 | 2.005 | — |
Applications
Where HN is used.
Frequently Asked Questions
Common questions about HN, answered from cross-validated data.
What is HN?
HN is an insulating, hydrogen-rich compound classified as a hydride that is frequently studied for its structural diversity despite its inherent thermodynamic instability.
What is HN used for?
What is the band gap of HN?
Is HN a metal, semiconductor, or insulator?
Is HN thermodynamically stable?
What is the crystal structure of HN?
What is the density of HN?
How many polymorphs of HN are known?
What elements does HN contain?
Where does the data for HN come from?
How It Compares
Within the hydrogen storage hydrides class.
Unlike the highly stable and widely utilized binary hydrides such as MgH2 or LiH, HN is distinguished by its relative thermodynamic instability. While members like MgH2 serve as robust benchmarks for reversible hydrogen storage, HN occupies a more complex structural space, reflecting the diverse and often challenging bonding environments found in nitrogen-containing hydrogen storage materials.
Related Compounds
Other Hydrogen Storage Hydrides in the database.
Data sources & attribution
- 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)
- 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)
- mpaloe — Data from MP-ALOE. Cite: Kuner et al., npj Comput. Mater. (2025), doi:10.1038/s41524-025-01834-9.
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