BorNitrid

Bornitrid, or boron nitride (BN), is a binary compound of boron and nitrogen that occurs in several crystalline polymorphs. The most common forms are hexagonal boron nitride (h-BN) and cubic boron nitride (c-BN). Other high-pressure phases such as wurtzite-type (w-BN) and rhombohedral (r-BN) exist under specific conditions. BN is typically a wide-band-gap, electrically insulating material with high chemical and thermal stability.

In its hexagonal form, BN has a layered structure similar to graphite, with strong in-plane bonds and weaker interlayer interactions. This gives h-BN excellent thermal stability, good lubricity, and anisotropic properties. The cubic form adopts a zinc blende structure, is superhard, and ranks among the hardest known materials after diamond. c-BN is chemically inert and maintains hardness at elevated temperatures, making it valuable as an abrasive and protective coating. BN materials generally show high thermal conductivity in the plane for h-BN and high dielectric strength as insulators.

Synthesis and processing methods vary by polymorph. h-BN can be produced by chemical vapor deposition, pyrolysis of borazine, or high-temperature synthesis of boron and nitrogen-containing precursors. c-BN is typically prepared under high pressure and high temperature, often with catalytic aids, to transform boron-containing precursors into the cubic phase. Processing also includes ceramic sintering and chemical vapor deposition to form BN powders, monoliths, or thin films.

Applications of BN span abrasives and cutting tools, protective and wear-resistant coatings, electrical insulators in high-temperature environments, and thermal management materials. BN is generally chemically inert and has low toxicity, though fine BN dust can pose inhalation and irritation risks if not handled with proper safety measures.