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Nanotube Research
Research School of Physical Sciences and Engineering
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Boron Nitride NanotubesNano Au-decorated boron nitride
nanotubes: Conductance modification and field-emission enhancement Hua Chen, Hongzhou Zhang,
Lan Fu, Ying Chen, James S. Williams, Chao Yu, and Dapeng Yu Abstract:
This letter reports the electrical and field-emission properties
of Au-decorated bamboo boron nitride nanotubes (Au-BNNTs). The insulating
BNNTs become metallic after Au coating as the Au coverage exceeds
a critical value. The Au decoration modifies the work function of
the BNNTs and, as a consequence, the field-emission current densities
of Au-BNNTs are significantly enhanced. Correspondingly, the turn-on
field of the Au-BNNTs is reduced to one third and the emission current
density is increased by four orders in contrast to pure BNNTs. The
experimental results demonstrate that such Au-BNNTs are promising
electron field emitters.
Fluorination-induced
magnetism in boron nitride nanotubes from ab initio calculations Feng Li, Zhonghua Zhu, Xiangdong
Yao, Gaoqing Lu, Mingwen Zhao, Yueyuan Xia, and Ying Chen Abstract:Ab initio calculations were conducted to
investigate the electronic structures and magnetic properties of fluorinated
boron nitride nanotube. It was found that the chemisorption of
Au doped BN nanotubes with tunable conductivity Abstract:Boron
nitride (BN) nanotubes with electric conductivities from semiconducting
to metallic have been achieved by controlled Au doping,
demonstrating a promising approach in tailoring of BN nanotube conductivities with the application potential in electronics, chemical catalysts, and sensing.
Eu-doped Boron Nitride Nanotubes as a
Nanometer-Sized Visible-Light Source Abstract:A broad and tunable visible light emission, excited by electrons, from Eu doped BN nanotubes has been realized for the first time. The special broad light emission is due to the insertion of Eu2+ ions into nanotube walls via in-situ Eu doping during nanotube growth instead of a common post-synthesis doping process.
Light emission and excitonic effect of boron nitride nanotubes observed by photoluminescent spectra Hua Chen, Ying Chen, Yun Liu, Chao-Nan Xu and Jim S. Williams
Abstract: Photoluminescent (PL) and optical absorption spectra of high-yield multi-wall BN nanotubes (BNNTs) were systematically investigated at room temperature in comparison with commercial hexagonal BN (h-BN) powder. The direct band gap of the BNNTs was determined to be 5.75 eV, just slightly narrower than that of h-BN powder (5.82 eV). Two Frenkel excitons with the binding energy of 1.27 and 1.35 eV were also determined. However, they were not a distinctive characteristic of the BNNTs as reported previously. Observed broad UV-visible-NIR light emission demonstrates the potential of the BNNTs as a nano light source.
Isotopically Enriched
10BN Nanotubes Abstract:Isotopically enriched 10BN nanotubes have been produced for the first time. SIMS analysis has confirmed a high content of 10B in the nanotubes. The 10BN nanotubes have light weight, excellent mechanical properties, a stronger resistance to oxidation and a better radiation shielding property, which offer a multifunctional material with promising aerospace applications.
In Situ Formation
of BN Nanotubes during Nitriding Reactions Abstract: High-yield multiwalled boron nitride (BN) nanotubes have been produced using a ball milling-annealing method. The BN nanotubes with a diameter less than 10 nm and a well-crystallized multiwalled structure were formed via an in situ nitriding reaction. The systematic investigation of the formation process at different annealing temperatures and for different times suggested that the formation of the unique multiwalled structure was attributed by a two-dimensional growth of the BN phase and a nonmetal catalytic growth.
Boron nitride
nanotubes: Pronounced resistance to oxidation Abstract: Boron nitride (BN) nanotubes have the same nanostructure as carbon nanotubes but are found to exhibit significant resistance to oxidation at high temperatures. Our systematic study has revealed that BN nanotubes are stable at 700 °C in air and that some thin nanotubes (diameter less than 20 nm) with perfect multiwalled cylindrical structure can survive up to 900 °C. Thermogravimetric analysis reveals an onset temperature for oxidation of BN nanotubes of 800 °C compared with only 400 °C for carbon nanotubes under the same conditions. This more pronounced resistance of BN nanotubes to oxidation is inherited from the hexagonal BN and also depends on the nanocrystalline structure. This high level of resistance to oxidation allows promising BN nanotube applications at high temperatures.
Solid-State Formation of
Carbon and Boron Nitride Nanotubes Abstract: Both carbon and boron nitride (BN) nanotubes have been produced by first ball milling of graphite and boron nitride powders at room temperature and then by isothermal annealing at temperatures less than 1500 oC. Ball milling creates the nuclei for nanotubes and the subsequent isothermal annealing is responsible for nanotube growth. Because the annealing temperatures are far below the melting points of both graphite and boron nitride, there are no vapor phases during the growth process. In contrast, x-ray diffraction and transmission electron microscopy reveal that the nanotubes grow from the ball milled powder clusters via solid-state crystal growth.
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