Aluminum nitride is a Covalent bond compound, belonging to the Hexagonal crystal family

Aluminum nitride is a Covalent bond compound, belonging to the Hexagonal crystal family, with a lead-zinc crystal structure, which is white or grayish white.

Chemical formula: AlN

CAS login number: 24304-00-5

Molecular weight: 40.9882

Aluminum nitride, Covalent bond compound, is a Network covalent bonding, which belongs to diamond like nitride, Hexagonal crystal family, Wurtzite type crystal structure, non-toxic, white or gray. Aluminum nitride (AlN) is an artificially synthesized mineral that does not exist naturally in nature. The crystal structure of AlN is hexagonal Wurtzite type, which has the advantages of low density (3.26g/cm3), high strength, good heat resistance (about 3060 ℃ decomposition), high thermal conductivity, corrosion resistance, etc.

Aluminum nitride (AlN) can be stabilized up to 2200 ℃. The room temperature strength is high, and the strength decreases slowly with the increase of temperature. With good thermal conductivity and small coefficient of thermal expansion, it is a good heat-resistant impact material. Strong resistance to molten metal erosion, making it an ideal crucible material for melting and casting pure iron, aluminum, or aluminum alloys.

AlN is a Network covalent bonding, a diamond-like nitride, which can be stabilized to 2200 ℃ at most. The room temperature strength is high, and the strength decreases slowly with the increase of temperature. With good thermal conductivity and small coefficient of thermal expansion, it is a good heat-resistant impact material. Strong resistance to molten metal erosion, making it an ideal crucible material for melting and casting pure iron, aluminum, or aluminum alloys. Aluminum nitride is still an electrical insulator with good dielectric properties, and it is also very promising for use as an electrical component. The aluminum nitride coating on the surface of gallium arsenide can protect it from ion implantation during annealing. Aluminum nitride is also a catalyst for transforming hexagonal Boron nitride into cubic Boron nitride. Slow reaction with water at room temperature. It can be synthesized from aluminum powder in ammonia or nitrogen atmosphere at 800-1000 ℃, and the product is a white to grayish blue powder. Alternatively, it can be synthesized from the Al2O3-C-N2 system at 1600~1750 ℃, resulting in a gray white powder. Or Aluminium chloride and ammonia through vapor phase reaction. The coating can be synthesized by vapor deposition from AlCl3-NH3 system.

Aluminum nitride was first synthesized in 1877. By the 1980s, because aluminum nitride was a ceramic insulator (polycrystalline material was 70-210 W · m − 1 · K − 1, and single crystal could be as high as 275 W · m − 1 · K − 1), aluminum nitride had a high heat transfer capacity, so that aluminum nitride was widely used in Microelectronics. Unlike Beryllium oxide, aluminum nitride is non-toxic. Aluminum nitride is treated with metal, which can replace bauxite and Beryllium oxide for a large number of electronic instruments.

It can be prepared by the reduction of aluminum oxide and carbon or by directly nitriding the metal aluminum. Aluminum nitride is a substance connected by Covalent bond. It has hexagonal crystal structure and is isomorphic with Zinc sulfide and fibrous zinc ore. The spatial group of this structure is P63mc. Industrial grade materials can only be manufactured by hot pressing and welding. Substances are very stable in inert high-temperature environments. When the temperature is above 700 ℃ in the air, oxidation occurs on the surface of the substance. At room temperature, oxide films with a thickness of 5-10 nanometers can still be detected on the surface of the substance. Until 1370 ℃, the oxide film can still protect the substance. But when the temperature is higher than 1370 ℃, a large amount of oxidation will occur. Until 980 ℃, aluminum nitride remains relatively stable in hydrogen and carbon dioxide. Mineral acids slowly dissolve granular substances by invading their boundaries, while strong bases dissolve granular aluminum nitride by invading it. The substance will slowly hydrolyze in water. Aluminum nitride can resist the invasion of most molten salts, including chlorides and Cryolite [i.e., sodium hexafluoroaluminate].

characteristic

(1) High thermal conductivity (about 20W/m · K), close to BeO and SiC, more than 5 times higher than Al2O3;

(2) Thermal expansion coefficient (4.5 × 10-6 ℃) and Si (3.5-4 × 10-6 ℃) and GaAs (6 × 10-6 ℃) matching;

(3) Various electrical properties (dielectric constant, dielectric loss, volume resistivity, Dielectric strength) are excellent;

(4) Good mechanical properties, higher flexural strength than Al2O3 and BeO ceramics, and can be sintered under normal pressure;

(5) High purity;

(6) Good optical transmission characteristics;

(7) Non toxic;

(8) Can be produced using casting process. It is a promising substrate and packaging material for high-power integrated circuits.

application

It is a good heat-resistant impact material and an ideal crucible material for melting and casting pure iron, aluminum or aluminum alloy

There are reports that most current research is developing a semiconductor based light emitting diode (LED) that operates in ultraviolet light, with a wavelength of 250 nanometers. In May 2006, there was a report stating that an inefficient diode could emit light waves with a wavelength of 210 nanometers. A 6.2eV energy gap was measured on a single aluminum nitride crystal using vacuum ultraviolet reflectance. In theory, the energy gap allows some waves with a wavelength of approximately 200 nanometers to pass through. But when implemented in business, many difficulties need to be overcome. Aluminum nitride is used in Optoelectronics, including optical storage interface and electronic matrix as induced layer, chip carrier under high thermal conductivity, and military use.

Due to the Piezoelectricity of aluminum nitride, the Extensionality extension of aluminum nitride crystals is also used for surface acoustic wave detectors. The detector will be placed on a silicon wafer. Only very few places can reliably manufacture these thin films.

Aluminum nitride ceramics have the characteristics of high room temperature and high temperature strength, low expansion coefficient, and good thermal conductivity, and can be used as heat exchanger materials for high-temperature structural components.

Utilizing the corrosion resistance of aluminum nitride ceramics to metals and alloys such as iron and aluminum, it can be used as a crucible and casting mold material for the melting of metals such as Al, Cu, Ag, and Pb.

security information

WGK Germany: 3

Hazard category: 4.1

Safety instructions: S26-S37/39

Packaging level: II

Dangerous goods transportation code: UN3178

Dangerous goods label: Xi: Irritant;

Hazard category code: R36/37/38