C4K2
C4K2 is a semimetallic, metastable binary compound composed of carbon and potassium.
About C4K2
C4K2 is a carbon-potassium compound that exhibits semimetallic behavior due to its near-zero-gap electronic structure. It is characterized as a complex material system with a significant number of reported structural configurations across various databases. Its unique electronic properties make it a subject of interest for fundamental studies in solid-state chemistry and carbon-based intercalation physics.
Because this compound is situated above the thermodynamic hull, it is considered inherently unstable under standard conditions. This instability highlights the delicate balance of atomic arrangements required to maintain such a structure, distinguishing it as a metastable phase that provides valuable insights into the energetic landscape of alkali-metal-doped carbon materials.
Key Properties
Cross-validated computational properties for C4K2, 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 C4K2, 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. |
|---|---|---|---|---|---|
| I4/mmm (No. 139) | tetragonal | 0.00 | 1.3079 | -7.364 | 1.47 |
| P4/nmm (No. 129) | tetragonal | 0.00 | 1.3080 | -7.364 | 1.47 |
| C2/c (No. 15) | monoclinic | 0.07 | 1.3193 | -7.353 | 1.46 |
| C2/m (No. 12) | monoclinic | 0.07 | 1.3249 | -7.347 | 1.46 |
| Immm (No. 71) | orthorhombic | 0.00 | 1.3319 | -7.340 | 1.40 |
| Cmcm (No. 63) | — | — | — | — | — |
| Imma (No. 74) | — | — | — | — | — |
| C2/m (No. 12) | — | — | — | — | — |
| P63/mmc (No. 194) | — | — | — | — | — |
| P63/mmc (No. 194) | — | — | — | — | — |
| Fd-3m (No. 227) | — | — | — | — | — |
| P63/mmc (No. 194) | — | — | — | — | — |
Applications
Where C4K2 is used.
Frequently Asked Questions
Common questions about C4K2, answered from cross-validated data.
What is C4K2?
C4K2 is a semimetallic, metastable binary compound composed of carbon and potassium.
What is C4K2 used for?
What is the band gap of C4K2?
Is C4K2 a metal, semiconductor, or insulator?
Is C4K2 thermodynamically stable?
What is the crystal structure of C4K2?
What is the density of C4K2?
How many polymorphs of C4K2 are known?
What elements does C4K2 contain?
Where does the data for C4K2 come from?
How It Compares
As a member of the alkali-metal-doped carbon family, C4K2 represents a specific stoichiometric arrangement that occupies a metastable position within the broader phase space of these materials. Unlike more stable, well-characterized intercalation compounds, its position above the thermodynamic hull suggests a high degree of structural sensitivity, making it a critical case study for understanding the limits of phase formation in binary carbon-potassium systems.
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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