NaC2
NaC2 is an unstable, semimetallic sodium-carbon compound characterized by a narrow electronic gap.
About NaC2
NaC2 is a binary compound composed of sodium and carbon that exhibits semimetallic electronic behavior. Its near-zero-gap nature suggests unique conductive properties that differentiate it from typical insulating or semiconducting carbon-based materials.
Due to its thermodynamic position above the hull, this compound is considered inherently unstable under standard conditions. Despite this, it remains a subject of interest in structural chemistry, with numerous reported configurations across various databases highlighting the complexity of the sodium-carbon system.
Key Properties
Cross-validated computational properties for NaC2, 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.
Reported Structures
Lowest-energy structures reported for NaC2, 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. |
|---|---|---|---|---|---|
| P4332 (No. 212) | cubic | 0.00 | 1.1407 | -6.679 | 3.16 |
| Immm (No. 71) | orthorhombic | 0.02 | 1.3924 | -6.427 | 1.49 |
| Pmmm (No. 47) | — | — | — | — | — |
| P21 (No. 4) | Monoclinic | — | — | — | 1.39 |
| Pmma (No. 51) | Orthorhombic | — | — | — | 1.92 |
| Pmma (No. 51) | Orthorhombic | — | — | — | 1.52 |
| P1 (No. 1) | Triclinic | — | — | — | 0.94 |
| P1 (No. 1) | Triclinic | — | — | — | 0.96 |
| P1 (No. 1) | Triclinic | — | — | — | 0.97 |
| C2/m (No. 12) | Monoclinic | — | — | — | 1.35 |
| C2/m (No. 12) | Monoclinic | — | — | — | 1.25 |
| P4332 (No. 212) | — | — | — | — | — |
Frequently Asked Questions
Common questions about NaC2, answered from cross-validated data.
What is NaC2?
NaC2 is an unstable, semimetallic sodium-carbon compound characterized by a narrow electronic gap.
What is the band gap of NaC2?
Is NaC2 a metal, semiconductor, or insulator?
Is NaC2 thermodynamically stable?
What is the crystal structure of NaC2?
What is the density of NaC2?
How many polymorphs of NaC2 are known?
What elements does NaC2 contain?
Where does the data for NaC2 come from?
How It Compares
As a sodium-carbon phase, NaC2 represents a specialized structural arrangement within the broader landscape of alkali metal carbides. While it lacks direct siblings in this specific dataset, it serves as a critical case study for understanding the challenges of synthesizing and stabilizing carbon-rich metallic compounds.
Data sources & attribution
- materials_project — Data from the Materials Project. Cite: Jain et al., APL Materials 1, 011002 (2013).
- jarvis — Data from JARVIS (NIST). Cite: Choudhary et al., npj Comp. Mater. 6, 173 (2020).
- mpaloe — Data from mpaloe.
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