H4NF
Ammonium fluoride · NH4F
Ammonium fluoride is a stable, insulating salt composed of ammonium and fluoride ions, widely used as an etchant and chemical reagent.
About Ammonium fluoride
Ammonium fluoride is a thermodynamically stable compound that functions as a wide-band-gap insulator. Its structural integrity and chemical properties make it a significant subject of investigation within the broader field of hydrogen-rich materials and chemical reagents. The compound is characterized by its ability to exist in multiple structural configurations, reflecting its versatility in solid-state chemistry. It is widely utilized in industrial etching processes and as a specialized chemical precursor where its specific fluoride-donating capabilities are required. Its stability on the convex hull underscores its importance as a reliable material for various synthetic and storage applications.
Key Properties
Cross-validated computational properties for Ammonium fluoride, aggregated across 3 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 H4NF. 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 H4NF, 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. |
|---|---|---|---|---|---|
| P-43m (No. 215) | cubic | 6.70 | 0.0000 | -0.882 | — |
| — | — | 6.45 | 0.0000 | -1.033 | — |
| P63mc (No. 186) | hexagonal | 5.96 | 0.0000 | -4.977 | 1.02 |
| P63mc (No. 186) | hexagonal | 5.98 | 0.0083 | -0.874 | — |
| R3c (No. 161) | trigonal | 6.18 | 0.0317 | -4.945 | 1.49 |
| — | — | 7.36 | 0.0523 | -0.980 | — |
| — | — | 7.30 | 0.0524 | -0.980 | — |
| — | — | 7.42 | 0.0572 | -0.975 | — |
| R-3m (No. 166) | trigonal | 0.76 | 0.9931 | 0.111 | — |
| P63mc (No. 186) | hexagonal | — | — | — | 1.05 |
| P63mc (No. 186) | hexagonal | — | — | — | 1.01 |
| P63mc (No. 186) | hexagonal | — | — | — | 1.00 |
Applications
Where Ammonium fluoride is used.
Frequently Asked Questions
Common questions about Ammonium fluoride, answered from cross-validated data.
What is H4NF?
Ammonium fluoride is a stable, insulating salt composed of ammonium and fluoride ions, widely used as an etchant and chemical reagent.
What is H4NF used for?
What is the band gap of H4NF?
Is H4NF a metal, semiconductor, or insulator?
Is H4NF thermodynamically stable?
What is the crystal structure of H4NF?
What is the density of H4NF?
How many polymorphs of H4NF are known?
What elements does H4NF contain?
Where does the data for H4NF come from?
How It Compares
Within the hydrogen storage hydrides class.
Unlike metal-based hydrogen storage hydrides such as MgH2 or CaH2, which primarily focus on reversible hydrogen release for energy applications, H4NF acts as a stable molecular-ionic solid. While LiH and AlH3 are often studied for their high hydrogen density, H4NF provides a distinct chemical environment due to the presence of the ammonium cation, making it a unique member of the hydride class compared to binary metal hydrides like CaClH.
Related Compounds
Other Hydrogen Storage Hydrides in the database.
Data sources & attribution
- 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)
- materials_project — Data from the Materials Project (materialsproject.org). Cite: Jain et al., APL Materials 1, 011002 (2013). (CC-BY-4.0)
- cod — Data from the Crystallography Open Database (crystallography.net/cod/). Cite: Grazulis et al., J. Appl. Cryst. 42, 726 (2009). (CC0-1.0)
- mpaloe — Data from MP-ALOE. Cite: Kuner et al., npj Comput. Mater. (2025), doi:10.1038/s41524-025-01834-9.
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