FeF2
Iron(II) fluoride · Ferrous fluoride
Iron(II) fluoride is a stable, semiconducting inorganic compound widely studied for its diverse structural configurations and fundamental material properties.
About Iron(II) fluoride
Iron(II) fluoride is a thermodynamically stable inorganic compound that exists as a semiconducting material. Its position on the convex hull underscores its structural reliability, making it a significant subject of study within materials science research. With a vast array of reported structures documented across major databases, this compound serves as a critical reference point for understanding transition metal halide behavior. Its electronic character and stability make it a foundational material for investigating magnetic and chemical properties in solid-state systems.
Key Properties
Cross-validated computational properties for Iron(II) 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 FeF2. 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 FeF2, 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. |
|---|---|---|---|---|---|
| P42/mnm (No. 136) | tetragonal | 1.69 | 0.0000 | -6.690 | 4.32 |
| — | — | 0.42 | 0.0000 | -2.192 | — |
| P42/mnm (No. 136) | tetragonal | 0.00 | 0.0000 | -2.011 | — |
| — | — | 0.42 | 0.0024 | -2.190 | — |
| — | — | 0.00 | 0.0239 | -2.169 | — |
| — | — | 0.43 | 0.0276 | -2.165 | — |
| — | — | 0.28 | 0.0443 | -2.148 | — |
| — | — | 0.00 | 0.0550 | -2.137 | — |
| — | — | 0.00 | 0.0621 | -2.130 | — |
| — | — | 1.01 | 0.0849 | -2.108 | — |
| — | — | 0.00 | 0.0938 | -2.099 | — |
| — | — | 0.00 | 0.1033 | -2.089 | — |
Applications
Where Iron(II) fluoride is used.
Patent Landscape
1 patent reference FeF2 or close compositional variants.
| Patent | Title | Assignee | Granted |
|---|---|---|---|
| 9231246 | Carbon-FeF2 and carbon-Fe203 nanocomposites, their preparation and use as electrochemical storage material | — | — |
Frequently Asked Questions
Common questions about Iron(II) fluoride, answered from cross-validated data.
What is FeF2?
Iron(II) fluoride is a stable, semiconducting inorganic compound widely studied for its diverse structural configurations and fundamental material properties.
What is FeF2 used for?
What is the band gap of FeF2?
Is FeF2 a metal, semiconductor, or insulator?
Is FeF2 thermodynamically stable?
What is the crystal structure of FeF2?
What is the density of FeF2?
How many polymorphs of FeF2 are known?
What elements does FeF2 contain?
Where does the data for FeF2 come from?
How It Compares
As a distinct transition metal halide, iron(II) fluoride serves as a primary example of stable binary fluoride systems, providing essential insights into the structural diversity and electronic behavior characteristic of this chemical class.
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)
- 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)
- 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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