Al2O9Si2
Kyanite · Cyanite, Disthene, Rhaeticite
Kyanite is a naturally occurring aluminum silicate mineral typically found in metamorphic rocks. It is highly valued in industrial settings for its structural stability and resistance to extreme heat.
Overview
Key Properties
Cross-validated computational properties for Kyanite, 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.
0.06–0.32 eV
Range across DFT structures
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.
0.317 eV/atom
Best (lowest) across sources
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.
Above hull
1 DFT source
StructuresCount of reported calculated crystal structures for this formula, including alternate polymorphs, source databases, and observed space groups.
10
3 databases, 3 space groups
Validation
Cross-Source DFT Agreement
How well independent DFT databases agree on the thermodynamics of Al2O9Si2. 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.
1.00 / 1.00
Trust tier: medium
Hull SpreadDifference between the highest and lowest energy-above-hull values reported by comparable sources. Smaller spread means less thermodynamic disagreement.
0.000 eV
EAH spread across sources
Sources ComparedNumber and names of computational sources with comparable entries for this formula.
1
materials_project
Space Group ConsensusWhether independent sources predict the same crystal symmetry for the lowest-energy structure.
All match
Crystallography
Reported Structures
Lowest-energy structures reported for Al2O9Si2, 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. |
|---|---|---|---|---|---|
| P1 (No. 1) | triclinic | 0.00 | 0.3167 | -7.353 | 2.40 |
| Cc (No. 9) | monoclinic | 0.32 | 0.3169 | -7.353 | 2.36 |
| Cc (No. 9) | monoclinic | 0.23 | 0.3176 | -7.352 | 2.36 |
| Cc (No. 9) | monoclinic | 0.00 | 0.3184 | -7.351 | 2.40 |
| Cc (No. 9) | monoclinic | 0.24 | 0.3185 | -7.351 | 2.40 |
| P1 (No. 1) | triclinic | 0.06 | 0.5887 | -7.081 | 2.29 |
| No. 0 | unknown | — | — | — | 0.64 |
| No. 0 | unknown | — | — | — | 1.28 |
| — | — | — | — | — | 2.35 |
| No. 0 | unknown | — | — | — | 0.64 |
Uses
Applications
Where Kyanite is used.
Refractory materialsCeramic productionElectrical insulatorsAbrasivesGemstones
Reference
Frequently Asked Questions
Common questions about Kyanite, answered from cross-validated data.
What is Al2O9Si2?
Kyanite is a naturally occurring aluminum silicate mineral typically found in metamorphic rocks. It is highly valued in industrial settings for its structural stability and resistance to extreme heat.
More questions
What is Al2O9Si2 used for?
Kyanite (Al2O9Si2) is used in refractory materials, ceramic production, electrical insulators, abrasives, and gemstones.
What is the band gap of Al2O9Si2?
Kyanite (Al2O9Si2) has a DFT-computed band gap of 0.06–0.32 eV across 10 reported structures.
Is Al2O9Si2 a metal, semiconductor, or insulator?
With a band gap up to 0.32 eV it is a semiconductor.
Is Al2O9Si2 thermodynamically stable?
Kyanite (Al2O9Si2) has a lowest energy above hull of 0.317 eV/atom (above hull).
What is the crystal structure of Al2O9Si2?
The lowest-energy reported polymorph of Kyanite (Al2O9Si2) is triclinic symmetry, space group P1 (No. 1).
What is the density of Al2O9Si2?
The computed density of the ground-state structure of Kyanite (Al2O9Si2) is 2.40 g/cm³.
How many polymorphs of Al2O9Si2 are known?
10 structures of Al2O9Si2 are reported across 3 databases, spanning 3 distinct space groups.
What elements does Al2O9Si2 contain?
Kyanite (Al2O9Si2) contains Al, O, and Si (3 elements).
Where does the data for Al2O9Si2 come from?
Al2O9Si2 data is cross-referenced from materials_project, cod, omat24.
Explore
Related Compounds
Other Aluminosilicates and Zeolite Frameworks in the database.
Data sources & attribution
- materials_project — Data from the Materials Project. Cite: Jain et al., APL Materials 1, 011002 (2013).
- cod — Data from the Crystallography Open Database. Cite: Grazulis et al., Nucleic Acids Res. 40, D420 (2012).
- omat24 — Data from OMat24 (Meta FAIR). Cite: Barroso-Luque et al., arXiv 2410.12771 (2024).
Analyze Al2O9Si2 in the Lattice Graph platform
Polymorph comparison, confidence scoring, supply-chain risk, and patent monitoring — across 53 integrated data sources.
Explore the Platform →