| 摘要 |
A body comprising a plurality of parallel pyrolytic boron nitride layers with alternate layers of a different pyrolytically deposited material is contacted with an intercalation material in fluid form, whereby the intercalation material enters the alternate layers decreasing the strength between them so that the boron nitride layers may be readily separated as sheets. The alternate layers may be pyrolytic carbonaceous material, e.g. graphite, or molybdenum, tantalum or aluminium nitride. The intercalation material is an electron acceptor material with a high electron affinity or an electron donor material with a low ionization potential, e.g. H2SO4 with a small amount of HNO3 or KClO4; AlCl3, BCl3, K, Co, ICl, Br2, AlCl, FeCl3, NaOH or KOH. The composite body comprising the boron nitride and alternate layers is built up by first depositing a layer of pyrolytic boron nitride from a vapour of b -trichloroborazole; or from BCl3 or B2H6 together with NH3, on to a plate of graphite and then depositing a layer of pyrolytic carbon, from methane gas, on to the boron nitride layer. Subsequent layers are built up by repeating the operation. |
