C4Rb4
C4Rb4 is a wide-gap insulating compound consisting of carbon and rubidium that is typically found in metastable states.
About C4Rb4
C4Rb4 is an insulating compound composed of carbon and rubidium. It is characterized by a wide electronic band gap, placing it firmly in the category of dielectric materials rather than metallic conductors. The compound exhibits significant structural diversity, with multiple configurations documented across various computational databases.
Despite its structural variety, C4Rb4 is identified as being above the thermodynamic hull, suggesting it is a metastable or unstable phase under standard conditions. Its existence is primarily of interest to researchers investigating the complex phase space of alkali metal-carbon systems and the fundamental limits of chemical stability in these binary mixtures.
Key Properties
Cross-validated computational properties for C4Rb4, aggregated across 5 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 C4Rb4, 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 | 3.53 | 0.3376 | -4.786 | 2.89 |
| P63/mmc (No. 194) | — | — | — | — | — |
| P63/mmc (No. 194) | — | — | — | — | — |
| Fm-3m (No. 225) | — | — | — | — | — |
| P63/mmc (No. 194) | — | — | — | — | — |
| No. 0 | unknown | — | — | — | 0.06 |
| Fm-3m (No. 225) | — | — | — | — | — |
| P63/mmc (No. 194) | — | — | — | — | — |
| — | — | — | — | — | 3.07 |
Frequently Asked Questions
Common questions about C4Rb4, answered from cross-validated data.
What is C4Rb4?
C4Rb4 is a wide-gap insulating compound consisting of carbon and rubidium that is typically found in metastable states.
What is the band gap of C4Rb4?
Is C4Rb4 a metal, semiconductor, or insulator?
Is C4Rb4 thermodynamically stable?
What is the crystal structure of C4Rb4?
What is the density of C4Rb4?
How many polymorphs of C4Rb4 are known?
What elements does C4Rb4 contain?
Where does the data for C4Rb4 come from?
How It Compares
As a unique binary system, C4Rb4 occupies a distinct position in materials research where it serves as a case study for the challenges of synthesizing and stabilizing complex carbon-alkali metal structures that exist outside of the thermodynamic ground state.
Data sources & attribution
- materials_project — Data from the Materials Project. Cite: Jain et al., APL Materials 1, 011002 (2013).
- nomad — Data from NOMAD. Cite: Draxl & Scheffler, J. Phys. Mater. 2, 036001 (2019).
- aflow — Data from AFLOW. Cite: Curtarolo et al., Comp. Mater. Sci. 58, 218 (2012).
- cod — Data from the Crystallography Open Database. Cite: Grazulis et al., Nucleic Acids Res. 40, D420 (2012).
- omat24 — Data from OMat24 (Meta FAIR). Cite: Barroso-Luque et al., arXiv 2410.12771 (2024).
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