Ar
Argon · noble gas
Argon is a chemically inert, wide-gap insulating noble gas widely used to provide protective atmospheres in industrial and scientific applications.
About Argon
Argon is a noble gas characterized by its exceptional chemical inertness and wide-gap insulating electronic structure. As a thermodynamically stable element, it exists as a monatomic gas under standard conditions and remains chemically unreactive due to its complete valence electron shell.
This stability makes it a vital component in modern technology, where it serves as a protective medium to prevent unwanted chemical reactions. Its prevalence in industrial applications stems from its ability to provide an inert environment during high-temperature processing and sensitive manufacturing tasks.
Key Properties
Cross-validated computational properties for Argon, aggregated across 6 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 Ar. 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 Ar, 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. |
|---|---|---|---|---|---|
| — | — | 8.94 | 0.0000 | 0.000 | — |
| Fm-3m (No. 225) | cubic | 8.72 | 0.0000 | 0.000 | — |
| P63/mmc (No. 194) | hexagonal | 8.71 | 0.0000 | 0.001 | — |
| Fm-3m (No. 225) | cubic | 8.51 | 0.0000 | -4.859 | 1.72 |
| P63/mmc (No. 194) | hexagonal | 8.51 | 0.0034 | -4.855 | 1.46 |
| — | — | 8.82 | 0.0082 | 0.008 | — |
| — | — | 9.11 | 0.0086 | 0.009 | — |
| — | — | 9.08 | 0.0089 | 0.009 | — |
| — | — | 8.87 | 0.0112 | 0.011 | — |
| — | — | 8.88 | 0.0125 | 0.012 | — |
| — | — | 8.65 | 0.0161 | 0.016 | — |
| — | — | 8.81 | 0.0173 | 0.017 | — |
Applications
Where Argon is used.
Frequently Asked Questions
Common questions about Argon, answered from cross-validated data.
What is Ar?
Argon is a chemically inert, wide-gap insulating noble gas widely used to provide protective atmospheres in industrial and scientific applications.
What is Ar used for?
What is the band gap of Ar?
Is Ar a metal, semiconductor, or insulator?
Is Ar thermodynamically stable?
What is the crystal structure of Ar?
How many polymorphs of Ar are known?
What elements does Ar contain?
Where does the data for Ar come from?
How It Compares
As a noble gas, Argon occupies a unique position in the periodic table, serving as the standard for inertness and stability within its elemental class.
Data sources & attribution
- 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)
- jarvis — Data from JARVIS (jarvis.nist.gov), NIST. Cite: Choudhary et al., npj Comp. Mater. 6, 173 (2020). (LicenseRef-US-Gov-PD)
- 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.
- cod — Data from the Crystallography Open Database (crystallography.net/cod/). Cite: Grazulis et al., J. Appl. Cryst. 42, 726 (2009). (CC0-1.0)
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