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Aluminium nitride

Aluminium nitride
Aluminium Nitride powder
Wurtzite polyhedra.png
Names
Other names
Aluminium nitride
Identifiers
24304-00-5 YesY
3D model (Jmol) Interactive image
ChEBI CHEBI:50884 YesY
ChemSpider 81668 YesY
ECHA InfoCard 100.041.931
EC Number 246-140-8
PubChem 90455
RTECS number BD1055000
Properties
AlN
Molar mass 40.9882 g/mol
Appearance white to pale-yellow solid
Density 3.260 g/cm3
Melting point 2,200 °C (3,990 °F; 2,470 K)
Boiling point 2,517 °C (4,563 °F; 2,790 K) decomposes
hydrolyses (powder), insoluble (monocrystalline)
Solubility insoluble, subject of hydrolysis in water solutions of bases and acids
Band gap 6.015 eV (direct)
Electron mobility ~300 cm2/(V·s)
Thermal conductivity 285 W/(m·K)
1.9–2.2
Structure
Wurtzite
C6v4-P63mc
Tetrahedral
Thermochemistry
30.1 J/mol K
20.2 J/mol K
318 kJ/mol
287.4 kJ/mol
Hazards
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 1: Exposure would cause irritation but only minor residual injury. E.g., turpentine Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
YesY  (what is YesYN ?)
Infobox references

Aluminium nitride (AlN) is a nitride of aluminium. Its wurtzite phase (w-AlN) is a wide band gap (6.01-6.05 eV at room temperature) semiconductor material, giving it potential application for deep ultraviolet optoelectronics.

AlN was first synthesized in 1877, but it was not until the middle of the 1980s that its potential for application in microelectronics was realized due to its relatively high thermal conductivity for an electrically insulating ceramic (70–210 W·m−1·K−1 for polycrystalline material, and as high as 285 W·m−1·K−1 for single crystals).

Aluminium nitride is stable at high temperatures in inert atmospheres and melts at 2800 °C. In a vacuum, AlN decomposes at ~1800 °C. In the air, surface oxidation occurs above 700 °C, and even at room temperature, surface oxide layers of 5-10 nm have been detected. This oxide layer protects the material up to 1370 °C. Above this temperature bulk oxidation occurs. Aluminium nitride is stable in hydrogen and carbon dioxide atmospheres up to 980 °C.

The material dissolves slowly in mineral acids through grain boundary attack, and in strong alkalies through attack on the aluminium nitride grains. The material hydrolyzes slowly in water. Aluminium nitride is resistant to attack from most molten salts, including chlorides and cryolite.

AlN is synthesized by the carbothermal reduction of aluminium oxide in the presence of gaseous nitrogen or ammonia or by direct nitridation of aluminium. The use of sintering aids, such as Y2O3 or CaO, and hot pressing is required to produce a dense technical grade material.


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