Ba
Barium · Ba
Barium is a reactive, metallic alkaline earth element that is thermodynamically stable and widely studied for its diverse structural properties.

About Barium
Barium is a soft, silvery-white alkaline earth metal that exhibits distinct metallic character. As a pure element, it is recognized for its high chemical reactivity and its tendency to readily form compounds with non-metals in various industrial and laboratory settings.
This element is thermodynamically stable, occupying a position on the convex hull that underscores its fundamental role in inorganic chemistry. Its extensive structural diversity is highlighted by numerous reported configurations across multiple materials databases, reflecting its complex behavior under varying conditions.
Key Properties
Cross-validated computational properties for Barium, 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.
Cross-Source DFT Agreement
How well independent DFT databases agree on the thermodynamics of Ba. 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 Ba, 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. |
|---|---|---|---|---|---|
| Im-3m (No. 229) | cubic | 0.00 | 0.0000 | -1.919 | 3.51 |
| Cmcm (No. 63) | orthorhombic | 0.00 | 0.0001 | -1.919 | 3.51 |
| Fm-3m (No. 225) | cubic | 0.00 | 0.0130 | -1.906 | 3.38 |
| P63/mmc (No. 194) | hexagonal | 0.00 | 0.0160 | -1.903 | 3.37 |
| Cmcm (No. 63) | orthorhombic | 0.00 | 0.0187 | -1.900 | 3.48 |
| I4/mcm (No. 140) | tetragonal | 0.00 | 0.1302 | -1.789 | 3.48 |
| P6/mmm (No. 191) | hexagonal | 0.00 | 0.1755 | -1.744 | 3.62 |
| Pm-3m (No. 221) | cubic | 0.00 | 0.2961 | -1.623 | 3.79 |
| P4/mmm (No. 123) | tetragonal | 0.00 | 0.3592 | -1.560 | 3.95 |
| Cmcm (No. 63) | orthorhombic | 0.00 | 0.5135 | -1.405 | 4.19 |
| P6/mmm (No. 191) | hexagonal | 0.00 | 0.7278 | -1.191 | 2.75 |
| Fm-3m (No. 225) | Cubic | — | — | — | 3.49 |
Applications
Where Barium is used.
Frequently Asked Questions
Common questions about Barium, answered from cross-validated data.
What is Ba?
Barium is a reactive, metallic alkaline earth element that is thermodynamically stable and widely studied for its diverse structural properties.
What is Ba used for?
What is the band gap of Ba?
Is Ba a metal, semiconductor, or insulator?
Is Ba thermodynamically stable?
What is the crystal structure of Ba?
What is the density of Ba?
How many polymorphs of Ba are known?
What elements does Ba contain?
Where does the data for Ba come from?
How It Compares
As a fundamental alkaline earth metal, Barium serves as a critical reference point for understanding the periodic trends of group two elements. Its metallic nature and structural stability make it a foundational material for studying reactivity and alloying behavior compared to lighter or heavier congeners within the periodic table.
Data sources & attribution
- materials_project — Data from the Materials Project. Cite: Jain et al., APL Materials 1, 011002 (2013).
- mpaloe — Data from mpaloe.
- cod — Data from the Crystallography Open Database. Cite: Grazulis et al., Nucleic Acids Res. 40, D420 (2012).
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