HBN

Hexagonal boron nitride (hBN) is a chemical compound composed of boron and nitrogen that adopts a layered hexagonal structure similar to graphite. Each layer consists of alternating boron and nitrogen atoms arranged in a two-dimensional hexagonal lattice, with strong covalent bonds within layers and weaker van der Waals forces between layers. hBN exists as a hexagonal polytype, in contrast to other BN forms such as cubic BN.

hBN is notable for its wide bandgap of about 5.9 eV, making it an electrical insulator and transparent to visible and much of the ultraviolet spectrum. It exhibits high thermal conductivity in the plane of the layers (on the order of several hundred watts per meter-kelvin) and low interlayer conductivity, yielding strong anisotropy. The material is chemically inert and thermally stable, with good resistance to oxidation up to high temperatures in air, and it serves as a dielectric and protective coating in various environments. Its mechanical stiffness and lubricity arise from the layered structure, enabling use as a solid lubricant.

Synthesis and forms: synthetic hBN is produced by high-temperature reactions of boron- and nitrogen-containing precursors, including chemical vapor deposition for large-area films. Exfoliation and milling produce nanosheets and flakes suitable for composites and 2D materials research. In bulk form, hBN occurs commercially as white powders and crystals.

Applications: hBN is used as a solid lubricant, protective coating, and filler to enhance thermal conductivity in polymers and composites. In electronics, it serves as a dielectric substrate and insulating layer for graphene and other 2D materials, and its wide bandgap enables deep-UV optoelectronic and high-temperature applications. The combination of thermal stability, chemical inertness, and dielectric properties makes hBN a versatile material across nanotechnology and engineering contexts.