A hexagonal boron nitride powder, in which an absolute value of a charge amount when 10 g of the hexagonal boron nitride powder is placed in a polyethylene terephthalate container with an inner diameter of 90 mm and a height of 120 mm and stirred at 300 rpm for 5 minutes using a stirring vane 60 mm in diameter with four polytetrafluoroethylene blades is 0.7 nc/g or less.

A floating catalyst chemical vapor deposition method for producing nanotubes, the method including: supplying a nanotube-material precursor and a catalyst precursor, heating said precursors and injecting said precursors into a heated reaction chamber containing a process gas; pyrolyzing the catalyst precursor within the reaction chamber to produce catalyst particles; and pyrolyzing the nanotube-material precursor within the reaction chamber in the presence of the catalyst particles in order to produce nanotubes; wherein the method further comprises controlling the size of the catalyst particles at the point of pyrolysis of the nanotube-material precursor by controlling the operational parameters of the reaction chamber and/or of the precursor supplies. A corresponding system for producing nanotubes is also provided. Further provided is an injector subsystem for attachment to a reaction chamber, the injector subsystem comprising: a first portion having a first set of injection pipes for receiving species for delivery into the reaction chamber; and an interface portion that is removably attachable between the first portion and the reaction chamber in use, the interface portion comprising at least one injection pipe arranged to receive the species provided by the first set of injection pipes and to inject said species into the reaction chamber in use; the injector subsystem being operable in use such that, with the interface portion removed, said first set of injection pipes are operable to individually inject their respective species into the reaction chamber, and with the interface portion attached, a pre-mixing chamber is defined by the interface portion in combination with the first portion, for pre-mixing the species provided by the first set of injection pipes prior to the species entering the at least one injection pipe of the interface portion.

A method of producing a spherical boron nitride fine particle includes reacting ammonia with an alkoxide borate at an ammonia/alkoxide borate molar ratio of 1 to 10 in an inert gas stream at 750 C. or higher within 30 seconds, then applying heat treatment to a reaction product in an atmosphere of ammonia gas or a mixed gas of ammonia gas and an inert gas at 1,000 to 1,600 C. for at least 1 hour, and further firing the reaction product in an inert gas atmosphere at 1,800 to 2,200 C. for at least 0.5 hour.

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.

It is an object to achieve a resin sheet having high thermal conductance and high dielectric strength. Hexagonal boron nitride powder in accordance with an aspect of the present invention includes hexagonal boron nitride agglomerate particles each including agglomerated hexagonal boron nitride primary particles, and has a specific surface area of not less than 0.5 m.sup.2/g and not more than 5.0 m.sup.2/g. The hexagonal boron nitride primary particles each have a long diameter of not less than 0.6 m and not more than 4.0 m and an aspect ratio of not less than 1.5 and not more than 5.0.

A composition comprising a boron nitride hexagonal lattice structure in which boron atoms and nitrogen atoms are present in a B:N molar ratio of 1:4-1:8 or 4:1-8:1, wherein the molar ratio corresponds to vacant site defects within the boron nitride hexagonal lattice structure. Also described are methods for producing the boron nitride composition as well as methods for using the boron nitride composition as a catalyst in a hydrogenation process.

There is provided a method for producing hexagonal boron nitride, including a heating step of heating a mixture containing boron carbide and an alkaline earth metal compound under an ammonia atmosphere at 1300-1500 C. to obtain a product containing hexagonal boron nitride, wherein a molar ratio of the boron carbide to the alkaline earth metal compound in the mixture is 0.5-2.0.

A heat spreader composed of a hexagonal boron carbon nitride (hBCN) thin film, can be a major solution for the ever-increasing problem of overheating electronic devices. This heat spreader can dissipate heat away from hotspots on electronic devices, unlocking additional processing power. Our method is able to effectively tune the thermal and electrical conductivity of our films by modulating the carbon content of the precursor used in a chemical vapor deposition (CVD) process. Using this method, we can generate a heat spreader that is electrically insulative, so it will not have the potential to create shorts, like graphene and metals. Additionally, we can maximize the thermal conductivity, obtaining a value of 460149 W/m.Math.K, which rivals or even surpasses hexagonal boron nitride (hBN). As our precursor material is 10 times cheaper than the most common hBN precursor, this is an economical alternative to hBN for heat spreader applications.

To provide a boron nitride powder having excellent heat conductivity and high particle strength. Provided is a boron nitride powder which comprises bulky boron nitride formed such that scaly primary particles of hexagonal boron nitride are aggregated to form bulky particles, and which has the following characteristics (A) to (C): (A) a particle strength of the bulky particles at a cumulative breakdown rate of 63.2% is 5.0 MPa or more; (B) an average particle size of the boron nitride powder is 2 m or more and 20 m or less; and (C) an orientation index of the boron nitride powder as determined from X-ray diffraction is 20 or less.

Feed material comprising uniform solution precursor droplets is processed in a uniform melt state using microwave generated plasma. The plasma torch employed is capable of generating laminar gas flows and providing a uniform temperature profile within the plasma. Plasma exhaust products are quenched at high rates to yield amorphous products. Products of this process include spherical, highly porous and amorphous oxide ceramic particles such as magnesia-yttria (MgOY.sub.2O.sub.3). The present invention can also be used to produce amorphous non oxide ceramic particles comprised of Boron, Carbon, and Nitrogen which can be subsequently consolidated into super hard materials.