FeO2
FeO2 is a semiconducting iron oxide material studied primarily as a high-capacity conversion anode for advanced energy storage technologies.
About FeO2
FeO2 is a semiconducting iron oxide that belongs to the class of conversion oxide anodes. These materials are investigated for their ability to store energy through chemical conversion reactions rather than traditional intercalation mechanisms, offering potential for high-capacity battery systems. Despite its complex structural landscape, it remains a subject of intense research interest within the materials science community. Due to its position above the thermodynamic hull, FeO2 is considered a metastable phase, which presents unique challenges and opportunities for synthesis and electrochemical performance optimization. Its electronic character and structural diversity make it a compelling candidate for fundamental studies into transition metal oxide behavior under extreme conditions.
Key Properties
Cross-validated computational properties for FeO2, 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 FeO2. 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 FeO2, 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 | 0.00 | 0.1452 | -7.399 | 4.61 |
| I41/amd (No. 141) | tetragonal | 0.00 | 0.1672 | -7.377 | 4.23 |
| I4/m (No. 87) | tetragonal | 1.15 | 0.1798 | -7.365 | 3.79 |
| P2/m (No. 10) | monoclinic | 0.00 | 0.1802 | -7.364 | 3.77 |
| Pm (No. 6) | monoclinic | 0.00 | 0.1862 | -7.358 | 3.82 |
| Pnma (No. 62) | orthorhombic | 0.00 | 0.2045 | -7.340 | 4.36 |
| C2/m (No. 12) | monoclinic | 0.00 | 0.2566 | -7.288 | 4.10 |
| Imma (No. 74) | orthorhombic | 0.00 | 0.2582 | -7.286 | 3.95 |
| Cm (No. 8) | monoclinic | 0.00 | 0.2709 | -7.274 | 3.90 |
| P1 (No. 1) | triclinic | 0.00 | 0.2713 | -7.273 | 3.91 |
| R-3m (No. 166) | trigonal | 0.00 | 0.2739 | -7.271 | 3.82 |
| P-3m1 (No. 164) | trigonal | 0.00 | 0.2746 | -7.270 | 3.90 |
Applications
Where FeO2 is used.
Frequently Asked Questions
Common questions about FeO2, answered from cross-validated data.
What is FeO2?
FeO2 is a semiconducting iron oxide material studied primarily as a high-capacity conversion anode for advanced energy storage technologies.
What is FeO2 used for?
What is the band gap of FeO2?
Is FeO2 a metal, semiconductor, or insulator?
Is FeO2 thermodynamically stable?
What is the crystal structure of FeO2?
What is the density of FeO2?
How many polymorphs of FeO2 are known?
What elements does FeO2 contain?
Where does the data for FeO2 come from?
How It Compares
Within the conversion oxide anodes class.
Within the broader family of conversion oxide anodes, FeO2 stands out for its high structural complexity compared to more conventional oxides like Fe2O3 or Fe3O4. While stable binary oxides such as SnO2 or CoO are widely utilized as benchmarks for electrochemical performance, the metastable nature of FeO2 positions it as a specialized subject for advanced material design rather than a standard commercial anode.
Related Compounds
Other Conversion Oxide Anodes in the database.
Data sources & attribution
- materials_project — Data from the Materials Project. Cite: Jain et al., APL Materials 1, 011002 (2013).
- cod — Data from the Crystallography Open Database. Cite: Grazulis et al., Nucleic Acids Res. 40, D420 (2012).
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