Cs2O
cesium oxide · dicesium oxide
Cesium oxide is a stable semiconducting binary compound formed from cesium and oxygen.
About cesium oxide
Cesium oxide is a binary inorganic compound composed of cesium and oxygen. As a thermodynamically stable material located on the convex hull, it represents a well-defined phase within the alkali metal oxide family, characterized by its distinct semiconducting electronic nature.
With extensive documentation across multiple structural databases, this compound is a significant subject of study for understanding alkali metal bonding and coordination chemistry. Its stable configuration makes it a primary reference point for researchers investigating the fundamental properties of heavy alkali oxides.
Key Properties
Cross-validated computational properties for cesium oxide, 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.
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 Cs2O. 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 Cs2O, 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. |
|---|---|---|---|---|---|
| — | — | 1.11 | 0.0000 | -1.112 | — |
| R-3m (No. 166) | trigonal | 0.58 | 0.0000 | -3.435 | 4.58 |
| — | — | 1.25 | 0.0017 | -1.110 | — |
| — | — | 1.25 | 0.0048 | -1.107 | — |
| — | — | 1.26 | 0.0050 | -1.107 | — |
| — | — | 1.35 | 0.0157 | -1.096 | — |
| — | — | 1.28 | 0.0158 | -1.096 | — |
| Pnma (No. 62) | orthorhombic | 1.65 | 0.0570 | -3.378 | 5.06 |
| Pnnm (No. 58) | orthorhombic | 0.27 | 0.0583 | -3.377 | 4.75 |
| — | — | 0.00 | 0.0669 | -1.045 | — |
| — | — | 1.00 | 0.0673 | -1.045 | — |
| — | — | 1.56 | 0.0674 | -1.045 | — |
Applications
Where cesium oxide is used.
Frequently Asked Questions
Common questions about cesium oxide, answered from cross-validated data.
What is Cs2O?
Cesium oxide is a stable semiconducting binary compound formed from cesium and oxygen.
What is Cs2O used for?
What is the band gap of Cs2O?
Is Cs2O a metal, semiconductor, or insulator?
Is Cs2O thermodynamically stable?
How many polymorphs of Cs2O are known?
What elements does Cs2O contain?
Where does the data for Cs2O come from?
How It Compares
As a foundational binary oxide, cesium oxide serves as a critical benchmark for evaluating the structural and electronic trends observed in the broader class of alkali metal oxides, providing essential insights into how cation size and electronegativity influence stability.
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)
- 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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