MgC2
MgC2 is a semiconducting magnesium carbide compound that exhibits complex structural behavior and is generally considered metastable.
About MgC2
MgC2 is a binary magnesium carbide characterized by its semiconducting electronic nature. Despite its simple elemental composition, it exhibits significant structural diversity, with numerous configurations documented across computational databases.
This compound is notable for its position relative to the thermodynamic ground state, as it is considered metastable. Its study provides critical insights into the bonding behavior of alkaline earth metals with carbon, serving as a point of interest for researchers investigating high-pressure phases and chemical stability.
Key Properties
Cross-validated computational properties for MgC2, 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.
Cross-Source DFT Agreement
How well independent DFT databases agree on the thermodynamics of MgC2. 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.
Hull SpreadDifference between the highest and lowest energy-above-hull values reported by comparable sources. Smaller spread means less thermodynamic disagreement.
Sources ComparedNumber and names of computational sources with comparable entries for this formula.
Space Group ConsensusWhether independent sources predict the same crystal symmetry for the lowest-energy structure.
Reported Structures
Lowest-energy structures reported for MgC2, 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. |
|---|---|---|---|---|---|
| P42/mnm (No. 136) | tetragonal | 2.75 | 0.2534 | 0.251 | — |
| — | — | 2.68 | 0.4193 | 0.419 | — |
| — | — | 2.59 | 0.4206 | 0.421 | — |
| P42/mnm (No. 136) | tetragonal | 2.56 | 0.4302 | -7.591 | 2.06 |
| P-1 (No. 2) | triclinic | 0.00 | 0.4756 | 0.474 | — |
| Cmmm (No. 65) | orthorhombic | 0.00 | 0.4990 | 0.497 | — |
| — | — | 0.45 | 2.1859 | 2.186 | — |
| — | — | 0.00 | 3.8237 | 3.824 | — |
| Cm (No. 8) | monoclinic | — | — | — | 2.64 |
| Cm (No. 8) | monoclinic | — | — | — | 2.43 |
| Cm (No. 8) | monoclinic | — | — | — | 2.42 |
| C2/m (No. 12) | monoclinic | — | — | — | 1.60 |
Applications
Where MgC2 is used.
Frequently Asked Questions
Common questions about MgC2, answered from cross-validated data.
What is MgC2?
MgC2 is a semiconducting magnesium carbide compound that exhibits complex structural behavior and is generally considered metastable.
What is MgC2 used for?
What is the band gap of MgC2?
Is MgC2 a metal, semiconductor, or insulator?
Is MgC2 thermodynamically stable?
What is the crystal structure of MgC2?
How many polymorphs of MgC2 are known?
What elements does MgC2 contain?
Where does the data for MgC2 come from?
How It Compares
As a member of the metal carbide family, MgC2 represents a unique case where the interplay between magnesium and carbon leads to a semiconducting state rather than the metallic behavior often seen in related transition metal carbides.
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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