Apr 9 2013
Boron nitride is a chemical compound having chemical formula BN comprising equal numbers of nitrogen and boron atoms. BN exists in a number of crystalline forms and is isoelectronic to a similarly structured carbon lattice. The hexagonal form corresponds to graphite, the cubic form to diamond and another form to wurtzite.
Boron nitride is not found naturally and is produced synthetically from boron trioxide or boric acid.
Applications
Due to high chemical and thermal stability, boron nitride ceramics are used as components of high-temperature equipment. Boron nitride has high prospects for nanotechnology. Boron nitride nanotubes can be produced that have a similar structure to carbon nanotubes such as graphene or boron nitride sheets rolled on themselves; however, with very different properties.
Chemical Properties
The chemical properties of boron nitride are provided in the table below:
| Chemical Properties |
| Chemical Formula |
BN |
| Molecular Weight |
24.82 |
| CAS No. |
10043-11-5 |
| IUPAC Name |
Boron nitride |
| Group |
III-V |
| Band Gap |
6.2 eV |
| Band Gap Type |
Direct |
| Crystal Structure |
Wurtzite, Zinc Blende, hexagonal |
| Symmetry Group |
C46v-P63mc, T2d-F43m, D6c-P63mmc |
| Lattice Constant |
2.55 A 3.615 A 2.5-2.9 A |
Electrical Properties
The electrical properties of boron nitride for Zinc Blende crystal structure are provided in the table below:
| Electrical Properties |
| Electron Mobility |
≤200 cm2 V-1 s-1 |
| Hole Mobility |
≤500 cm2 V-1 s-1 |
| Electron Diffusion Coefficient |
≤5 cm2 s-1 |
| Hole Diffusion Coefficient |
≤12 cm2 s-1 |
Thermal, Mechanical and Optical Properties
The thermal, mechanical and optical properties of boron nitride are provided in the tables below:
| Mechanical Properties |
| Melting Point |
2973 °C |
| Density |
3.4870 g cm-3 3.450 g cm-3 2.0-2.28 g cm-3 |
| Bulk Modulus |
400 GPa 400 GPa 36.5 GPa |
| Thermal Properties |
| Thermal Conductivity |
7.4 W cm-1 °C-1 |
| Thermal Diffusivity |
1.47 cm2 s-1 |
| Thermal Expansion Coefficient |
5.27x10-6 °C-1 |
| Specific Heat |
~0.75 J g-1°C-1 ~0.6 J g-1 °C-1 ~0.8 J g-1 °C-1 |
| Optical Properties |
| Infrared Refractive Index (300 K) |
Wurtzite~=2.05 |
Hexagonal ~=2.1 |
ZincBlende ~=1.8 |
Safety Information
| Safety Information |
| Hazard Statements |
H 319- Causes serious eye irritation H335 – May cause respiratory irritation |
| Hazard Codes |
Xi - Irritant |
| Safety Precautions |
S26, S36 |