CaO
calcium oxide · quicklime, burnt lime
Calcium oxide is a widely used chemical compound produced by the thermal decomposition of limestone. It is a fundamental material in industrial manufacturing, serving as a key ingredient in the production of construction materials and as a chemical reagent in various processes.
Key Properties
Cross-validated computational properties for calcium 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 CaO. 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 CaO, 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 | 3.63 | 0.0000 | -6.783 | 3.35 |
| P63/mmc (No. 194) | hexagonal | 3.12 | 0.1043 | -6.678 | 2.82 |
| Cmce (No. 64) | orthorhombic | 2.09 | 0.2098 | -6.573 | 2.00 |
| I4/mmm (No. 139) | tetragonal | 1.74 | 0.2099 | -6.573 | 1.97 |
| P1 (No. 1) | triclinic | 2.47 | 0.2954 | -6.487 | 2.82 |
| P1 (No. 1) | triclinic | 2.14 | 0.3111 | -6.472 | 2.81 |
| P1 (No. 1) | triclinic | 2.00 | 0.3415 | -6.441 | 2.79 |
| Fd-3m (No. 227) | cubic | 0.00 | 2.7281 | -4.055 | 2.97 |
| Fm-3m (No. 225) | — | — | — | — | — |
| Cm (No. 8) | Monoclinic | — | — | — | 2.27 |
| P3m1 (No. 156) | Trigonal | — | — | — | 1.87 |
| Pm (No. 6) | Monoclinic | — | — | — | 2.02 |
Synthesis Routes
Literature-extracted synthesis procedures targeting CaO.
Applications
Where calcium oxide is used.
Frequently Asked Questions
Common questions about calcium oxide, answered from cross-validated data.
What is CaO?
Calcium oxide is a widely used chemical compound produced by the thermal decomposition of limestone. It is a fundamental material in industrial manufacturing, serving as a key ingredient in the production of construction materials and as a chemical reagent in various processes.
What is CaO used for?
What is the band gap of CaO?
Is CaO a metal, semiconductor, or insulator?
Is CaO thermodynamically stable?
What is the crystal structure of CaO?
What is the density of CaO?
How many polymorphs of CaO are known?
How is CaO synthesized?
What elements does CaO contain?
Where does the data for CaO come from?
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.
Analyze CaO in the Lattice Graph platform
Polymorph comparison, confidence scoring, supply-chain risk, and patent monitoring — across 53 integrated data sources.
Explore the Platform →