Rapid Synthesis of Boron Nitride Nanotubes
Publication Date: 2010-Oct-25
The IP.com Prior Art Database
This disclosure of a "Rapid Synthesis of Boron Nitride Nanotubes" outlines a procedure for the synthesis of boron nitride (BN) nanotubes via a sold-state, self-propagating double exchange (metathesis) reaction. The reaction allows for the synthesis of bulk quantities of BN nanotubes from a reaction between inexpensive precursors and requires no heating or time consuming growth procedures. This allows for the high volume, high speed production of BN nanotubes at low cost.
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BN nanotubes have been formed from a solid state reaction between lithium amide and lithium tetrafluoroborate in the presence of a transition metal (FeCl3) catalyst. The reaction proceeds according to the following equation:
LiBF4 + Li3N BN (nanotubes) + 4 LiF
The reactants are ground or ball milled together in the presence of the catalyst after which the mixture is initiated either by heating or by exposure to a hot object; the preferred method of initiation being exposure to a resistively heated metal (Nichrome) wire. The amount of catalyst required can vary greatly, however in the reaction shown above, a 5 mole % quantity of FeCl3 was used (relative to LiBF4) Upon initiation the reaction is self propagating, that is, it runs to completion without the need for any additional external heating or other additional energy input. The reactant mixture must be prepared under an inert atmosphere to prevent water and/or oxygen contamination of the reactants. The BN nanotube product is air stable and can be separated from the LiF salt by-product by rinsing all of the products with water and using a filtration process to separate the solid BN product from the aqueous LiF solution.
The exothermic reaction proceeds rapidly upon initiation and the entire synthesis is complete less than one second after initiation. Due to the exothermic nature and fast kinetics of this reaction, it should be run within the confines of a sealed vessel, such as a steel bomb calo...