Ar
Argon · Noble gas
Argon is a chemically inert noble gas that makes up a small portion of the Earth's atmosphere. Because it does not readily react with other substances, it is widely used to provide protective environments for sensitive industrial and scientific processes.
Ar
Overview
Key Properties
Cross-validated computational properties for Argon, aggregated across 4 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.
8.51 eV
Range across DFT structures
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.
0.000 eV/atom
Best (lowest) across sources
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.
On hull (stable)
3 DFT sources
StructuresCount of reported calculated crystal structures for this formula, including alternate polymorphs, source databases, and observed space groups.
11
4 databases, 2 space groups
Crystallography
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. |
|---|---|---|---|---|---|
| Fm-3m (No. 225) | cubic | 8.51 | 0.0000 | -4.859 | 1.72 |
| P63/mmc (No. 194) | hexagonal | 8.49 | 0.0034 | -4.855 | 1.46 |
| P63/mmc (No. 194) | — | — | — | — | — |
| Fm-3m (No. 225) | — | — | — | — | — |
| Fm-3m (No. 225) | Cubic | — | — | — | 1.48 |
| Fm-3m (No. 225) | Cubic | — | — | — | 1.51 |
| Fm-3m (No. 225) | — | — | — | — | — |
| Fm-3m (No. 225) | Cubic | — | — | — | 1.49 |
| P63/mmc (No. 194) | Hexagonal | — | — | — | 1.47 |
| P63/mmc (No. 194) | Hexagonal | — | — | — | 1.48 |
| P63/mmc (No. 194) | Hexagonal | — | — | — | 1.51 |
Uses
Applications
Where Argon is used.
Inert gas shielding for arc weldingFilling for incandescent and fluorescent light bulbsThermal insulation in double-pane windowsPurge gas for semiconductor manufacturingPreservation of historical documents
Reference
Frequently Asked Questions
Common questions about Argon, answered from cross-validated data.
What is Ar?
Argon is a chemically inert noble gas that makes up a small portion of the Earth's atmosphere. Because it does not readily react with other substances, it is widely used to provide protective environments for sensitive industrial and scientific processes.
More questions
What is Ar used for?
Argon (Ar) is used in inert gas shielding for arc welding, filling for incandescent and fluorescent light bulbs, thermal insulation in double-pane windows, purge gas for semiconductor manufacturing, and preservation of historical documents.
What is the band gap of Ar?
Argon (Ar) has a DFT-computed band gap of 8.51 eV across 11 reported structures.
Is Ar a metal, semiconductor, or insulator?
With a wide band gap up to 8.51 eV it is an insulator / wide-band-gap material.
Is Ar thermodynamically stable?
Yes — Argon (Ar) sits on the convex hull (energy above hull 0 eV/atom), i.e. on hull (stable).
What is the crystal structure of Ar?
The lowest-energy reported polymorph of Argon (Ar) is cubic symmetry, space group Fm-3m (No. 225).
What is the density of Ar?
The computed density of the ground-state structure of Argon (Ar) is 1.72 g/cm³.
How many polymorphs of Ar are known?
11 structures of Ar are reported across 4 databases, spanning 2 distinct space groups.
What elements does Ar contain?
Argon (Ar) contains Ar (1 element).
Where does the data for Ar come from?
Ar data is cross-referenced from materials_project, jarvis, mpaloe, nomad.
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.
- nomad — Data from NOMAD. Cite: Draxl & Scheffler, J. Phys. Mater. 2, 036001 (2019).
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