Very long single- and few-walled boron nitride nanotubes via the pressurized vapor/condenser method

Abstract

Keyword: boron nitride nanotubesBoron nitride nanotubes (BNNTs) are desired for their exceptional mechanical, electronic, thermal, structural, textural, optical, and quantum properties. Golberg [1] gives an excellent review of possible applications. To date, BNNTs have been grown by a number of techniques which can be divided roughly into two categories based on the class of material produced.One is the high temperature category in which energy is concentrated into a B or BN target at a level which can vaporize elemental boron. BNNTs form in the deposits of the liberated vapors. The energy is input by laser [2][3][4][5][6] or by arc discharge [7][8][9] . Only small quantities (mg's) of material have been produced by this method, but the tubes are high quality. They have one or just a few walls, and most importantly, the tube walls are low in defects and parallel to the axis of the nanotube. The second category is low temperature synthesis, between about 600 C and 1700 C, well below the vaporization temperature of pure boron (~4000 C). These low temperature synthesis methods can be further divided into two catagories. In the first category, ball-milled precursor powders of boron and catalyst are annealed in a nitrogen or ammonia gas atmosphere, sprouting nanostructures on their

Covalent Functionalization of Boron Nitride Nanotubes via Reduction Chemistry

“…A similar curvature-dependent trend has been observed for various carbon nanomaterials in the literature (e.g., EA(CNT (5,0) ) > EA(fullerene) > EA(CNT (5,5) )). 28 This finding implies that the curvature-induced π orbital misalignment results in an enhanced reactivity toward extra electrons, whereby nanotubes release strain energy associated with high curvature by reduction.…”

“…EA calculations were carried out with supercells of armchair [ (5,5) and (10,10)] and zigzag [(5,0) and (10,0] nanotubes for both C and BN systems. We used rectangular model cells, whose xÀy dimensions perpendicular to the tube axis were 30 Å, chosen sufficiently large enough to avoid the tubeÀtube interactions from adjacent unit cells.…”

Molar Binding Energy of Zigzag and Armchair Single-Walled Boron Nitride Nanotubes

“…Recently the development of a new method for producing long, small-diameter, single-and few-walled, BN nanotubes in macroscopic quantities has been reported [22]. The pressurized vapor/condenser (PVC) method produces highly crystalline, very long, small-diameter nanotubes without catalysts.…”

Modeling of Laser Vaporization and Plume Chemistry in a Boron Nitride Nanotube Production Rig

“…Not included in this review is a description of a recently developed and unique hightemperature, pressurized vapor condensation (PVC) method. 2 The NASA Langley Research Center (LaRC), National Institute of Aerospace (NIA) and Jefferson Sciences Association/DoE team discovered that this novel synthesis method produces thin, long, high aspect ratio, highly crystalline BNNTs using a conventional laser at high pressure. 2 The PVC method appears to minimize tube defects and create exceptionally long (order mm) tubes.…”

“…2 The NASA Langley Research Center (LaRC), National Institute of Aerospace (NIA) and Jefferson Sciences Association/DoE team discovered that this novel synthesis method produces thin, long, high aspect ratio, highly crystalline BNNTs using a conventional laser at high pressure. 2 The PVC method appears to minimize tube defects and create exceptionally long (order mm) tubes. The synthesis of longer tubes is advantageous for structural reinforcement applications, where it is more likely that the desired strength properties will extend from the nanoscale to the macroscale.…”