CaO2
calcium peroxide · calcium dioxide
Calcium peroxide is a stable, solid chemical compound that releases oxygen when exposed to moisture, making it useful for environmental and agricultural applications.
About calcium peroxide
Calcium peroxide is a robust, thermodynamically stable compound that functions as a solid source of oxygen. Its semiconducting electronic nature and structural reliability make it a versatile material for controlled chemical oxidation processes.
Because it releases oxygen upon contact with water, it is frequently utilized in applications requiring sustained aeration or the remediation of contaminated soils and groundwater. Its stability ensures it remains effective during storage and deployment in diverse environmental conditions.
Key Properties
Cross-validated computational properties for calcium peroxide, 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 CaO2. 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 CaO2, 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. |
|---|---|---|---|---|---|
| — | — | 2.93 | 0.0000 | -2.280 | — |
| I4/mmm (No. 139) | tetragonal | 2.78 | 0.0000 | -6.174 | 3.31 |
| P-1 (No. 2) | triclinic | 2.02 | 0.0000 | -2.200 | — |
| I4/mmm (No. 139) | tetragonal | 2.98 | 0.0558 | -2.144 | — |
| C2/m (No. 12) | monoclinic | 2.56 | 0.0575 | -2.143 | — |
| — | — | 2.97 | 0.1064 | -2.173 | — |
| C2/m (No. 12) | monoclinic | 0.00 | 0.2813 | -5.892 | 2.84 |
| C2/c (No. 15) | monoclinic | 0.00 | 0.2834 | -5.890 | 2.81 |
| P-3m1 (No. 164) | trigonal | 0.00 | 0.4944 | -5.679 | 2.85 |
| — | — | 0.00 | 1.3507 | -0.929 | — |
| — | — | 0.00 | 1.3730 | -0.907 | — |
| P1 (No. 1) | triclinic | — | — | — | 2.85 |
Applications
Where calcium peroxide is used.
Frequently Asked Questions
Common questions about calcium peroxide, answered from cross-validated data.
What is CaO2?
Calcium peroxide is a stable, solid chemical compound that releases oxygen when exposed to moisture, making it useful for environmental and agricultural applications.
What is CaO2 used for?
What is the band gap of CaO2?
Is CaO2 a metal, semiconductor, or insulator?
Is CaO2 thermodynamically stable?
What is the crystal structure of CaO2?
What is the density of CaO2?
How many polymorphs of CaO2 are known?
What elements does CaO2 contain?
Where does the data for CaO2 come from?
How It Compares
As a standalone member of its chemical class, calcium peroxide serves as a benchmark for peroxide-based oxygen delivery, offering superior stability and controlled reactivity compared to more volatile liquid or unstable solid oxidants.
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)
- jarvis — Data from JARVIS (jarvis.nist.gov), NIST. Cite: Choudhary et al., npj Comp. Mater. 6, 173 (2020). (LicenseRef-US-Gov-PD)
- mpaloe — Data from MP-ALOE. Cite: Kuner et al., npj Comput. Mater. (2025), doi:10.1038/s41524-025-01834-9.
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