C2Hf2
C2Hf2 has a DFT band gap of 0.30 eV across 41 reported structures in 15 space groups; its lowest-energy polymorph is cubic (Fm-3m (No. 225)). Cross-validated across 3 computational databases.
At a glance
Key Properties
Cross-validated computational properties for C2Hf2, 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.
0.30 eV
Range across DFT structures
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.
On hull (stable)
1 DFT source
StructuresCount of reported calculated crystal structures for this formula, including alternate polymorphs, source databases, and observed space groups.
41
3 databases, 15 space groups
Crystallography
Reported Structures
Lowest-energy structures reported for C2Hf2, 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. |
|---|---|---|---|---|---|
| Fm-3m (No. 225) | cubic | 0.00 | 0.0000 | -28.672 | 12.71 |
| P63/mmc (No. 194) | hexagonal | 0.00 | 0.1972 | -28.475 | 12.57 |
| F-43m (No. 216) | cubic | 0.30 | 0.6414 | -28.031 | 9.87 |
| P-6m2 (No. 187) | hexagonal | 0.00 | 0.7634 | -27.909 | 12.00 |
| Pm-3m (No. 221) | cubic | 0.00 | 1.3391 | -27.333 | 13.02 |
| R-3m (No. 166) | — | — | — | — | — |
| Cmcm (No. 63) | — | — | — | — | — |
| P63/mmc (No. 194) | — | — | — | — | — |
| Imma (No. 74) | — | — | — | — | — |
| Fd-3m (No. 227) | — | — | — | — | — |
| P63mc (No. 186) | — | — | — | — | — |
| Fm-3m (No. 225) | — | — | — | — | — |
Reference
Frequently Asked Questions
Common questions about C2Hf2, answered from cross-validated data.
What is the band gap of C2Hf2?
C2Hf2 has a DFT-computed band gap of 0.30 eV across 41 reported structures.
More questions
Is C2Hf2 a metal, semiconductor, or insulator?
With a band gap up to 0.30 eV it is a semiconductor.
Is C2Hf2 thermodynamically stable?
Yes — C2Hf2 sits on the convex hull (energy above hull 0 eV/atom), i.e. on hull (stable).
What is the crystal structure of C2Hf2?
The lowest-energy reported polymorph of C2Hf2 is cubic symmetry, space group Fm-3m (No. 225).
What is the density of C2Hf2?
The computed density of the ground-state structure of C2Hf2 is 12.71 g/cm³.
How many polymorphs of C2Hf2 are known?
41 structures of C2Hf2 are reported across 3 databases, spanning 15 distinct space groups.
What elements does C2Hf2 contain?
C2Hf2 contains C and Hf (2 elements).
Where does the data for C2Hf2 come from?
C2Hf2 data is cross-referenced from materials_project, aflow.
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Related Compounds
Other Ultra-High-Temperature Ceramics in the database.
Data sources & attribution
- materials_project — Data from the Materials Project. Cite: Jain et al., APL Materials 1, 011002 (2013).
- aflow — Data from AFLOW. Cite: Curtarolo et al., Comp. Mater. Sci. 58, 218 (2012).
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