NaFeO2
Sodium ferrite · Sodium iron oxide
NaFeO2 is a stable, semiconducting sodium iron oxide used primarily as a model material in the development of advanced sodium-ion battery cathodes.
About Sodium ferrite
NaFeO2 is a prominent member of the layered sodium transition-metal oxide family, characterized by its semiconducting electronic nature and robust thermodynamic stability. As a material that resides on the convex hull, it serves as a fundamental building block for understanding structural evolution in alkali-metal intercalation systems.
Its significance lies in its role as a precursor and active component in energy storage technologies, particularly within the development of sodium-ion batteries. Due to its well-documented structural diversity, it remains a highly studied compound for optimizing cathode performance and ion transport kinetics.
Key Properties
Cross-validated computational properties for Sodium ferrite, 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 NaFeO2. 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 NaFeO2, 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. |
|---|---|---|---|---|---|
| R-3m (No. 166) | trigonal | 1.96 | 0.0000 | -6.725 | 4.37 |
| R-3m (No. 166) | trigonal | 0.00 | 0.0000 | -1.592 | — |
| R-3m (No. 166) | trigonal | 0.00 | 0.0000 | -1.592 | — |
| — | — | 1.68 | 0.0019 | -1.809 | — |
| — | — | 1.70 | 0.0026 | -1.809 | — |
| — | — | 1.69 | 0.0165 | -1.795 | — |
| P41212 (No. 92) | tetragonal | 0.82 | 0.0270 | -6.698 | 3.16 |
| — | — | 1.81 | 0.0346 | -1.777 | — |
| — | — | 1.80 | 0.0420 | -1.769 | — |
| — | — | 1.80 | 0.0428 | -1.768 | — |
| Pna21 (No. 33) | orthorhombic | 2.05 | 0.0499 | -6.675 | 3.22 |
| — | — | 1.20 | 0.0596 | -1.752 | — |
Synthesis Routes
Literature-extracted synthesis procedures targeting NaFeO2.
Applications
Where Sodium ferrite is used.
Frequently Asked Questions
Common questions about Sodium ferrite, answered from cross-validated data.
What is NaFeO2?
NaFeO2 is a stable, semiconducting sodium iron oxide used primarily as a model material in the development of advanced sodium-ion battery cathodes.
What is NaFeO2 used for?
What is the band gap of NaFeO2?
Is NaFeO2 a metal, semiconductor, or insulator?
Is NaFeO2 thermodynamically stable?
What is the crystal structure of NaFeO2?
What is the density of NaFeO2?
How many polymorphs of NaFeO2 are known?
How is NaFeO2 synthesized?
What elements does NaFeO2 contain?
Where does the data for NaFeO2 come from?
Related Research
How It Compares
Within the layered sodium transition-metal oxides class.
Within the diverse class of layered sodium transition-metal oxides, NaFeO2 stands out as a stable iron-based variant compared to the more complex or cobalt-rich members like NaCoO2 or Na2FeO3. While materials like NaNiO2 are frequently explored for their specific electrochemical activity, NaFeO2 provides a critical baseline for iron-based systems, offering a more abundant and cost-effective alternative to the noble-metal-containing analogs.
Related Compounds
Other Layered Sodium Transition-Metal Oxides 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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