What is hBN?

hBN (hexagonal boron nitride) is the low density polymorph of boron nitride. It is composed of sp2-hybridised B-N layers, where each of the layers is composed of interlinked hexagonal rings. It is an entirely synthetic material, generally produced through the reductive nitridation of boron oxide. It is a white solid which is stable up to high temperatures in air and is therefore used in refractory applications or as a high-temperature lubricant. Although it is often referred to as "white graphite" because of its similarity to graphite in bulk mechanical properties, other physical and chemical properties of hBN are quite different to those of graphite. It is electrically insulating (rather than conductive) and is white (rather than black).