*** Welcome to piglix ***

Hexagonal boron nitride

Boron nitride
Magnified sample of crystalline hexagonal boron nitride
Names
IUPAC name
Boron nitride
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.030.111
EC Number 233-136-6
216
MeSH Elbor
PubChem CID
RTECS number ED7800000
UNII
Properties
BN
Molar mass 24.82 g·mol−1
Appearance Colorless crystals
Density 2.1 (h-BN); 3.45 (c-BN) g/cm3
Melting point 2,973 °C (5,383 °F; 3,246 K) sublimates (cBN)
insoluble
Electron mobility 200 cm2/(V·s) (cBN)
1.8 (h-BN); 2.1 (c-BN)
Structure
hexagonal, sphalerite, wurtzite
Thermochemistry
19.7 J/(K·mol)
14.8 J/K mol
-254.4 kJ/mol
-228.4 kJ/mol
Hazards
Irritant Xi
R-phrases (outdated) R36/37
S-phrases (outdated) S26, S36
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 0: Exposure under fire conditions would offer no hazard beyond that of ordinary combustible material. E.g., sodium chloride 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
Related compounds
Related compounds
Boron arsenide

Boron carbide
Boron phosphide
Boron trioxide

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N  (what is YesYN ?)
Infobox references

Boron carbide
Boron phosphide
Boron trioxide

Boron nitride is a heat- and chemically resistant refractory compound of boron and nitrogen with the chemical formula BN. It exists in various crystalline forms that are isoelectronic to a similarly structured carbon lattice. The hexagonal form corresponding to graphite is the most stable and soft among BN polymorphs, and is therefore used as a lubricant and an additive to cosmetic products. The cubic (sphalerite structure) variety analogous to diamond is called c-BN; it is softer than diamond, but its thermal and chemical stability is superior. The rare wurtzite BN modification is similar to lonsdaleite and may even be harder than the cubic form.

Because of excellent thermal and chemical stability, boron nitride ceramics are traditionally used as parts of high-temperature equipment. Boron nitride has potential use in nanotechnology. Nanotubes of BN can be produced that have a structure similar to that of carbon nanotubes, i.e. graphene (or BN) sheets rolled on themselves, but the properties are very different.

Boron nitride exists in multiple forms that differ in the arrangement of the boron and nitrogen atoms, giving rise to varying bulk properties of the material.

The amorphous form of boron nitride (a-BN) is non-crystalline, lacking any long-distance regularity in the arrangement of its atoms. It is analogous to amorphous carbon.


...
Wikipedia

...