The present invention provides a process for producing a two-dimensional nanomaterial, the process comprising forming the two-dimensional nanomaterial on a surface of a substrate by CVD, wherein said surface is a liquid surface which comprises a molten eutectic compound. Substrates and substrate precursors for use in said process are also provided.

BN nanosheets are prepared by a method comprising heating to a temperature of at least 500 C., a mixture comprising: (1) an alkali borohydride, and (2) an ammonium salt. NaN.sub.3 may be included to increase the yield. No catalyst is required, and the product produced contains less than 0.1 atomic percent metal impurities.

The present application relates to boron nitride nanotube (BNNT)-nanoparticle composites, to methods of preparing such composites and their use, for example, in metal/ceramic matrix composites and/or macroscopic assemblies. For example, the methods comprise subjecting a source of hydrogen, a source of boron, a source of nitrogen and a nanoparticle precursor to a stable induction thermal plasma and cooling the reaction mixture to obtain the composite.

A boron nitride fine particle has low major diameter/thickness (aspect) ratio, high purity and high crystallinity, and also has an average particle diameter of 0.05 to 2.0 m, a graphitization index of 3 or less, and a total oxygen content of 0.20% by mass or less, with an average value of a major diameter/thickness ratio of scaly particles being 6.0 or less. A method of producing a boron nitride fine particle includes introducing ammonia and an alkoxide borate at an ammonia/alkoxide borate molar ratio of 1 to 5 in a reaction vessel in an inert gas atmosphere for heating at 800 to 1,350 C. within 30 seconds thereby obtaining a boron nitride precursor, and then heating the boron nitride precursor at 1,650 to 2,200 C. for at least 0.5 hour in an inert gas atmosphere.