Ca2O3
Ca2O3 is a semiconducting calcium oxide phase that exists as a metastable material with various reported structural configurations.
About Ca2O3
Ca2O3 is a semiconducting oxide compound composed of calcium and oxygen. Despite its composition, it remains a subject of interest in materials science due to the diverse structural arrangements it can adopt under varying conditions.
This material is characterized by its position above the thermodynamic hull, suggesting it is a metastable phase. Its existence across multiple reported structures highlights the complex landscape of calcium-rich oxides and the ongoing efforts to synthesize and stabilize such unique binary compounds.
Key Properties
Cross-validated computational properties for Ca2O3, 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 Ca2O3. 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 Ca2O3, 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. |
|---|---|---|---|---|---|
| — | — | 2.67 | 0.1618 | -2.485 | — |
| P1 (No. 1) | triclinic | 0.20 | 0.2142 | -6.203 | 2.63 |
| — | — | 0.00 | 0.4698 | -2.176 | — |
| — | — | 0.00 | 0.4703 | -2.176 | — |
| — | — | 0.00 | 0.4835 | -2.163 | — |
| P1 (No. 1) | triclinic | — | — | — | 1.79 |
| C2 (No. 5) | monoclinic | — | — | — | 2.68 |
| P1 (No. 1) | triclinic | — | — | — | 2.77 |
| Cm (No. 8) | monoclinic | — | — | — | 2.46 |
| C2 (No. 5) | monoclinic | — | — | — | 2.74 |
| Pm (No. 6) | monoclinic | — | — | — | 2.58 |
| C2/m (No. 12) | monoclinic | — | — | — | 1.36 |
Applications
Where Ca2O3 is used.
Frequently Asked Questions
Common questions about Ca2O3, answered from cross-validated data.
What is Ca2O3?
Ca2O3 is a semiconducting calcium oxide phase that exists as a metastable material with various reported structural configurations.
What is Ca2O3 used for?
What is the band gap of Ca2O3?
Is Ca2O3 a metal, semiconductor, or insulator?
Is Ca2O3 thermodynamically stable?
How many polymorphs of Ca2O3 are known?
What elements does Ca2O3 contain?
Where does the data for Ca2O3 come from?
How It Compares
As a member of the calcium-oxygen binary system, Ca2O3 represents a less conventional stoichiometry compared to the more common, thermodynamically stable calcium oxides. It serves as a case study in metastable phase exploration, where researchers investigate how specific synthesis pathways might access structures that are not the ground-state configuration.
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.
- aflow — Data from AFLOW (aflow.org). Cite: Curtarolo et al., Comp. Mater. Sci. 58, 218 (2012). (CC-BY-4.0)
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