Nanomaterials Synthesis & Analysis Group
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1.High-yield synthesis of BN nanosheets
It is possible to achieve high-yield synthesis of BN nanosheets by using a mechanical separation process on BN powder in a solvent with high polarity (dimethyl formamide, DMF). While the thickness of the nanosheets depends on the rotation speed of the separator, it ranges between 1 and 10nm.
 
2.BN nanotube polymeric composites and high-yield synthesis of ultra-pure BN nanotubes
Using the carbon-free CVD method, we developed a method for the high-yield synthesis of ultra-pure BN nanotubes at the gram level. By combining BN nanotubes with polymers such as polystyrene, we created BN polymeric composites 20 times more thermally conductive than the original substance. It is expected that these polymeric composites can be used as highly thermally conductive and insulative materials for IC base plates.
 
3.High-yield synthesis of BN nanoparticles

Using the CVD method, we developed a method for the high-yield synthesis of BN nanoparticles by allowing trimethoxyborane (B(O)Me3) to react with ammonia at high temperatures. By reheating the product, we were able to synthesize low oxygen-containing well-crystalline BN nanoparticles of approximately 1% wt and 30nm in diameter.

4.Fabrication of ZnS nanowires and ultraviolet sensors
A characteristic of single crystalline ZnS nanowires is that, at room temperature, they emit sharp ultraviolet (UV) light at a wavelength of 337nm and can detect UV rays emitted between wavelengths of 330 and 400nm. Given this, we fabricated high quality single crystalline ZnS nanowires and elucidated their efficacy as ultraviolet sensors.
 
5.Fabrication of In2Se3 nanowires and optical sensors
Using the CVD method, we successfully fabricated aligned, single crystal In2Se3 nanowires. In2Se3 nanowires can be used as invertible fast-response optical sensors, and their photocurrent can be amplified when doped with sulfur.
6.In-situ observation with TEM-STM of BN nanotube property changes upon deformation
Using a TEM-STM holder, we observed changes in electrical resistance concurrent with the deformation of BN nanotubes in-situ. BN nanotubes are insulators with a resistance of 2 GΩ, but we discovered that when they are drastically deformed, their resistance falls to 260 MΩ and they behave as conductors of electricity. This is because elastic deformation significantly modifies their band structure, transforming them from insulators into semiconductors.
 
7.Discovery of carbon nanothermometer
We found that a carbon nanotube including liquid gallium can work as a thermometer. The expansion of liquid gallium in the carbon nanotube is proportional to temperature and fully reversible. Gallium is supercooled up to -80 oC and it remains liquid due to a confinement effect. The results were published in Nature (2002), and reviewed in The Dairy Yomiuri and New York Times, and had a wide resonance. Furthermore, the nanothermometer was recorded in the Guinness Book as the world smallest thermometer(2004). Nanothermometers are expected to be used as a local temperature sensor on a micron scale, and to be useful for trouble-shooting of semiconducting devices and bio-sensors.
 
8.Novel nanotubes of ZnS, GaN, AlN and InN
Numerous novel nanotubes are created by a CVD method and their structures are analyzed.
 
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