Nb2C
Nb2C has a DFT band gap of Metallic / not reported across 138 reported structures in 24 space groups; its reference structure is orthorhombic (Pnma (No. 62)). Cross-validated across 3 computational databases.
At a glance
Key Properties
Cross-validated computational properties for Nb2C, 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.
Metallic / not reported
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.
0.000 eV/atom
Best (lowest) across sources
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.
Stable
3 DFT sources
StructuresCount of reported calculated crystal structures for this formula, including alternate polymorphs, source databases, and observed space groups.
138
3 databases, 24 space groups
Validation
Cross-Source DFT Agreement
How well independent DFT databases agree on the thermodynamics of Nb2C. 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.
1.00 / 1.00
Trust tier: high
Hull SpreadDifference between the highest and lowest energy-above-hull values reported by comparable sources. Smaller spread means less thermodynamic disagreement.
0.000 eV
EAH spread across sources
Sources ComparedNumber and names of computational sources with comparable entries for this formula.
3
jarvis, materials_project, oqmd
Space Group ConsensusWhether independent sources predict the same crystal symmetry for the lowest-energy structure.
All match
Crystallography
Reported Structures
Lowest-energy structures reported for Nb2C, 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. |
|---|---|---|---|---|---|
| Pnma (No. 62) | orthorhombic | 0.00 | 0.0000 | -0.485 | — |
| Pnma (No. 62) | orthorhombic | 0.00 | 0.0000 | -0.485 | — |
| — | — | 0.00 | 0.0000 | -0.474 | — |
| Pnma (No. 62) | orthorhombic | 0.00 | 0.0000 | -20.341 | 7.68 |
| P-3m1 (No. 164) | trigonal | 0.00 | 0.0101 | -20.331 | 7.66 |
| P-3m1 (No. 164) | trigonal | 0.00 | 0.0155 | -0.470 | — |
| — | — | 0.00 | 0.0159 | -0.458 | — |
| — | — | 0.00 | 0.7152 | 0.241 | — |
| — | — | 0.00 | 1.1021 | 0.628 | — |
| — | — | 0.00 | 2.5433 | 2.069 | — |
| — | — | 0.00 | 2.6431 | 2.169 | — |
| P1 (No. 1) | triclinic | — | — | — | 7.09 |
Reference
Frequently Asked Questions
Common questions about Nb2C, answered from cross-validated data.
What is the band gap of Nb2C?
The reported DFT structures of Nb2C show no band gap. Standard DFT often misses gaps (especially in transition-metal oxides), so this is not proof the real material is a metal.
More questions
Is Nb2C a metal, semiconductor, or insulator?
DFT calculations predict no band gap. Standard DFT can miss gaps, so measurements are needed to confirm metallic behavior.
Is Nb2C thermodynamically stable?
Yes — Nb2C sits on the convex hull (energy above hull 0 eV/atom), i.e. stable.
What is the crystal structure of Nb2C?
The reference structure of Nb2C is orthorhombic symmetry, space group Pnma (No. 62).
How many polymorphs of Nb2C are known?
138 structures of Nb2C are reported across 3 databases, spanning 24 distinct space groups.
What elements does Nb2C contain?
Nb2C contains C and Nb (2 elements).
Where does the data for Nb2C come from?
Nb2C data is cross-referenced from jarvis, oqmd, materials_project, mpaloe.
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Related Compounds
Other Ultra-High-Temperature Ceramics 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)
- mpaloe — Data from MP-ALOE. Cite: Kuner et al., npj Comput. Mater. (2025), doi:10.1038/s41524-025-01834-9.
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