Ca2Al2SiO7
Gehlenite · Melilite
Gehlenite is a stable, insulating aluminosilicate mineral that serves as a key structural component in various ceramic and geological systems.
About Gehlenite
Ca2Al2SiO7, commonly known as gehlenite, is a prominent member of the melilite group within the broader class of aluminosilicates. As a thermodynamically stable phase, it maintains a robust structural integrity that makes it a significant subject of study in mineralogy and materials science.
This compound exhibits wide-gap insulating behavior, characteristic of its complex oxide framework. Its stability and structural versatility allow it to serve as a foundational component in various high-temperature industrial processes and ceramic formulations.
Key Properties
Cross-validated computational properties for Gehlenite, 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 Ca2Al2SiO7. 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 Ca2Al2SiO7, 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. |
|---|---|---|---|---|---|
| P21 (No. 4) | monoclinic | 4.45 | 0.0000 | -3.310 | — |
| P21 (No. 4) | monoclinic | 4.33 | 0.0002 | -7.761 | 2.95 |
| P-421m (No. 113) | tetragonal | 4.28 | 0.0213 | -7.740 | 2.98 |
| — | — | 4.59 | 0.0230 | -3.291 | — |
| P-421m (No. 113) | tetragonal | 4.58 | 0.0304 | -3.280 | — |
| P212121 (No. 19) | orthorhombic | 3.68 | 0.1743 | -7.587 | 2.77 |
| P212121 (No. 19) | orthorhombic | 3.21 | 0.3095 | -7.452 | 2.72 |
| P-421m (No. 113) | tetragonal | — | — | — | 3.05 |
| P-421m (No. 113) | tetragonal | — | — | — | 3.04 |
| P-421m (No. 113) | tetragonal | — | — | — | 3.02 |
| P-421m (No. 113) | tetragonal | — | — | — | 3.06 |
| P21 (No. 4) | monoclinic | — | — | — | 2.95 |
Synthesis Routes
Literature-extracted synthesis procedures targeting Ca2Al2SiO7.
Applications
Where Gehlenite is used.
Frequently Asked Questions
Common questions about Gehlenite, answered from cross-validated data.
What is Ca2Al2SiO7?
Gehlenite is a stable, insulating aluminosilicate mineral that serves as a key structural component in various ceramic and geological systems.
What is Ca2Al2SiO7 used for?
What is the band gap of Ca2Al2SiO7?
Is Ca2Al2SiO7 a metal, semiconductor, or insulator?
Is Ca2Al2SiO7 thermodynamically stable?
What is the crystal structure of Ca2Al2SiO7?
What is the density of Ca2Al2SiO7?
How many polymorphs of Ca2Al2SiO7 are known?
How is Ca2Al2SiO7 synthesized?
What elements does Ca2Al2SiO7 contain?
Where does the data for Ca2Al2SiO7 come from?
How It Compares
Within the aluminosilicates and zeolite frameworks class.
Within the diverse family of aluminosilicates, Ca2Al2SiO7 is closely related to Sr2Al2SiO7, sharing a similar melilite-type structural framework. While compounds like Al2SiO5 exist as distinct polymorphs with different coordination environments, gehlenite is distinguished by its specific calcium-based stoichiometry, which provides a unique balance of thermal and chemical stability compared to alkali-bearing framework silicates such as NaAlSi3O8.
Related Compounds
Other Aluminosilicates and Zeolite Frameworks in the database.
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)
- mpaloe — Data from MP-ALOE. Cite: Kuner et al., npj Comput. Mater. (2025), doi:10.1038/s41524-025-01834-9.
- cod — Data from the Crystallography Open Database (crystallography.net/cod/). Cite: Grazulis et al., J. Appl. Cryst. 42, 726 (2009). (CC0-1.0)
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