Ca3SiO5
tricalcium silicate · alite, C3S
Tricalcium silicate is a key insulating compound that acts as the primary active ingredient in Portland cement, responsible for the initial setting and strength development of concrete.
About tricalcium silicate
Tricalcium silicate is a complex calcium silicate that serves as a fundamental building block in modern construction materials. As a wide-gap insulating compound, it possesses the structural characteristics necessary for high-performance applications in the built environment. Its thermodynamic profile indicates that it is a stable phase, making it a reliable subject for materials research.
This compound is highly significant due to its central role in the hydration chemistry that allows cement to harden. Its structural complexity and the abundance of reported phases underscore its importance in both industrial manufacturing and fundamental materials science studies.
Key Properties
Cross-validated computational properties for tricalcium silicate, aggregated across 3 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 Ca3SiO5. 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 Ca3SiO5, 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. |
|---|---|---|---|---|---|
| P63mc (No. 186) | hexagonal | 3.03 | 0.0184 | -3.263 | — |
| P-1 (No. 2) | triclinic | 3.99 | 0.0201 | -7.439 | 3.06 |
| P63mc (No. 186) | hexagonal | 2.93 | 0.0288 | -7.430 | 3.00 |
| Cm (No. 8) | monoclinic | 3.89 | 0.0342 | -3.247 | — |
| R3m (No. 160) | trigonal | 3.46 | 0.0406 | -3.241 | — |
| R3m (No. 160) | trigonal | 3.28 | 0.0499 | -7.409 | 3.00 |
| — | — | 3.54 | 0.0540 | -3.249 | — |
| R3m (No. 160) | trigonal | 3.27 | 0.0613 | -7.398 | 2.96 |
| R3m (No. 160) | trigonal | 3.70 | 0.0617 | -7.397 | 3.04 |
| Cm (No. 8) | monoclinic | 3.86 | 0.0636 | -7.395 | 3.11 |
| — | — | 3.86 | 0.0649 | -3.238 | — |
| — | — | 4.22 | 0.0947 | -3.209 | — |
Synthesis Routes
Literature-extracted synthesis procedures targeting Ca3SiO5.
Applications
Where tricalcium silicate is used.
Frequently Asked Questions
Common questions about tricalcium silicate, answered from cross-validated data.
What is Ca3SiO5?
Tricalcium silicate is a key insulating compound that acts as the primary active ingredient in Portland cement, responsible for the initial setting and strength development of concrete.
What is Ca3SiO5 used for?
What is the band gap of Ca3SiO5?
Is Ca3SiO5 a metal, semiconductor, or insulator?
Is Ca3SiO5 thermodynamically stable?
What is the crystal structure of Ca3SiO5?
How many polymorphs of Ca3SiO5 are known?
How is Ca3SiO5 synthesized?
What elements does Ca3SiO5 contain?
Where does the data for Ca3SiO5 come from?
How It Compares
As a primary constituent of Portland cement, this compound stands as a cornerstone of inorganic silicate chemistry. It represents a critical phase in the calcium-silicon-oxygen system, serving as the benchmark for reactivity and strength development in hydraulic binders.
Data sources & attribution
- jarvis — Data from JARVIS (jarvis.nist.gov), NIST. Cite: Choudhary et al., npj Comp. Mater. 6, 173 (2020). (LicenseRef-US-Gov-PD)
- materials_project — Data from the Materials Project (materialsproject.org). Cite: Jain et al., APL Materials 1, 011002 (2013). (CC-BY-4.0)
- 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)
- cod — Data from the Crystallography Open Database (crystallography.net/cod/). Cite: Grazulis et al., J. Appl. Cryst. 42, 726 (2009). (CC0-1.0)
- mpaloe — Data from MP-ALOE. Cite: Kuner et al., npj Comput. Mater. (2025), doi:10.1038/s41524-025-01834-9.
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