Al2H4O9Si2

Kaolinite · clay mineral, aluminum silicate hydroxide

Al2H4O9Si2 is a stable, insulating aluminosilicate mineral widely used in industrial applications ranging from ceramics to paper production.

Crystal structure of Al2H4O9Si2 (monoclinic, Cc (No. 9))
Ground-state structure · Materials Project
Overview

About Kaolinite

Al2H4O9Si2 is a prominent member of the aluminosilicate family, characterized by its insulating electronic properties and robust structural framework. As a near-hull phase, it exhibits high thermodynamic stability, making it a naturally occurring and easily synthesizable material of significant geological and industrial importance.

This compound serves as a foundational material in various mineralogical and synthetic applications. Its layered structure and chemical resilience allow it to function effectively in high-performance ceramics, as a filler in paper manufacturing, and as a critical component in specialized chemical processes.

At a glance

Key Properties

Cross-validated computational properties for Kaolinite, aggregated across 3 databases.

Band Gap

1.67–4.95 eV
Range across DFT structures · ground state: insulator

Energy Above Hull

0.018 eV/atom
Best (lowest) across sources

Stability

Near Hull
2 DFT sources

Structures

38
3 databases, 3 space groups
Validation

Cross-Source DFT Agreement

How well independent DFT databases agree on the thermodynamics of Al2H4O9Si2. Tight agreement means computed properties can be trusted without re-running calculations.

Only 1 independent DFT source (materials_project) reports a hull energy for Al2H4O9Si2, so cross-source agreement can't be assessed yet.

Crystallography

Reported Structures

Lowest-energy structures reported for Al2H4O9Si2, ranked by energy above hull.

Space GroupCrystal SystemBand Gap (eV)E above hull (eV/atom)E/atom (eV)Density (g/cm³)
Cc (No. 9)monoclinic4.930.0180-7.1092.50
P1 (No. 1)triclinic4.930.0187-7.1082.52
Cc (No. 9)monoclinic4.870.0202-7.1062.46
Cc (No. 9)monoclinic4.950.0211-7.1062.49
Cm (No. 8)monoclinic4.950.0225-7.1042.54
Cm (No. 8)monoclinic4.510.0357-7.0912.46
Cc (No. 9)monoclinic4.230.3813-6.7451.81
Cc (No. 9)monoclinic0.000.6689-6.4581.89
P1 (No. 1)triclinic4.93—-6.7442.52
P1 (No. 1)triclinic4.93—-6.7442.52
P1 (No. 1)triclinic4.93—-6.7442.52
P1 (No. 1)triclinic4.93—-6.7442.52
Uses

Applications

Where Kaolinite is used.

Ceramics manufacturingPaper coating and fillingPharmaceutical excipientsRubber and paint additivesCosmetic formulations
Reference

Frequently Asked Questions

Common questions about Kaolinite, answered from cross-validated data.

What is Al2H4O9Si2?

Al2H4O9Si2 is a stable, insulating aluminosilicate mineral widely used in industrial applications ranging from ceramics to paper production.

More questions
What is Al2H4O9Si2 used for?
Kaolinite (Al2H4O9Si2) is used in ceramics manufacturing, paper coating and filling, pharmaceutical excipients, rubber and paint additives, and cosmetic formulations.
What is the band gap of Al2H4O9Si2?
Kaolinite (Al2H4O9Si2) has a DFT-computed band gap of 1.67–4.95 eV across 38 reported structures. Standard DFT underestimates band gaps, so the measured gap is typically larger.
Is Al2H4O9Si2 a metal, semiconductor, or insulator?
DFT predicts a wide band gap of up to 4.95 eV (an insulator or wide-band-gap material).
Is Al2H4O9Si2 thermodynamically stable?
Kaolinite (Al2H4O9Si2) has a lowest energy above hull of 0.018 eV/atom (near hull).
What is the crystal structure of Al2H4O9Si2?
The reference structure of Kaolinite (Al2H4O9Si2) is monoclinic symmetry, space group Cc (No. 9).
What is the density of Al2H4O9Si2?
The computed density of the ground-state structure of Kaolinite (Al2H4O9Si2) is 2.50 g/cm³.
How many polymorphs of Al2H4O9Si2 are known?
38 structures of Al2H4O9Si2 are reported across 3 databases, spanning 3 distinct space groups.
What elements does Al2H4O9Si2 contain?
Kaolinite (Al2H4O9Si2) contains Al, H, O, and Si (4 elements).
Where does the data for Al2H4O9Si2 come from?
Al2H4O9Si2 data is cross-referenced from materials_project, aflow, cod.
Comparison

How It Compares

Within the aluminosilicates and zeolite frameworks class.

Within the diverse class of aluminosilicates, Al2H4O9Si2 stands out for its distinct layered morphology compared to the more rigid, three-dimensional framework structures found in minerals like NaAlSi3O8 or the dense, high-pressure phases such as Al2SiO5. While compounds like CaAl2SiO6 often form under different geological conditions, Al2H4O9Si2 remains one of the most accessible and widely utilized members of the group due to its stability and abundance.

Explore

Related Compounds

Other Aluminosilicates and Zeolite Frameworks in the database.

Data sources & attribution
  • materials_project — Data from the Materials Project (materialsproject.org). Cite: Jain et al., APL Materials 1, 011002 (2013). (CC-BY-4.0)
  • aflow — Data from AFLOW (aflow.org). Cite: Curtarolo et al., Comp. Mater. Sci. 58, 218 (2012). (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)

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