Boron nitride nanotubes (BNNTs) have extraordinary mechanical properties ideal as reinforcements in composites and offer the possibility of a tunable band gap for electronic applications. But synthesizing BNNTs has proven difficult, with current methods requiring high temperatures, special-ized instrumentation and producing nanotubes of low quality contaminated with impurities. Now researchers from Michigan Technological University believe they have changed all this using an approach that makes the growth of BNNTs as simple and convenient as carbon nanotubes [C.H. Lee et al., Chem. Mater. (2009), doi:10.1021/cm903287u]. Using catalytic chemical vapordeposition (CCVD) at 1200 ◦C with MgO, Ni or Fe catalysts, Yoke Khin Yap and his team have achieved patterned growth of BNNTs directly on Si substrates for the first time
Category: Bnnt
Diameter-Dependent Bending Modulus of Individual Multiwall Boron Nitride Nanotubes
The mechanical properties of individual multi-wall boron nitride nanotubes (MWBNNTs) synthesized by a growth-vapor-trapping chemical vapor deposition method are investigated by a three-point bending technique via atomic force microscopy. Multiple locations on suspended tubes are probed in order to determine the boundary conditions of the supported tube ends. The bending moduli (EB) calculated for 20 tubes with diameters ranging from 18 to 58 nm confirm the exceptional mechanical properties of MWBNNTs, with an average EB of 760 ± 30 GPa. For the first time, the bending moduli of MWBNNTs are observed to increase with decreasing diameter, ranging from 100 ± 20 GPa to as high as 1800 ± 300 GPa. This diameter dependence is evaluated by Timoshenko beam theory. The Young’s modulus and shear modulus were determined to be 1800 ± 300 and 7 ± 1 GPa, respectively, for a trimmed data set of 16 tubes. The low shear modulus of MWBNNTs is the reason for the detected diameter-dependent bending modulus and is likely due to the presence of interwall shearing between the crystalline and faceted helical nanotube structures of MWBNNTs.
Switching Behaviors of Graphene- Boron Nitride Nanotube Heterojunctions
High electron mobility of graphene has enabled their application in high-frequency analogue devices but their gapless nature has hindered their use in digital switches. In contrast, the structural analogous, h-BN sheets and BN nanotubes (BNNTs) are wide band gap insulators. Here we show that the growth of electrically insulating BNNTs on graphene can enable the use of graphene as effective digital switches. These graphene-BNNT heterojunctions were characterized at room temperature by four-probe scanning tunneling microscopy (4-probe STM) under real-time monitoring of scanning electron microscopy (SEM). A switching ratio as high as 105 at a turn-on voltage as low as 0.5V were recorded. Simulation by density functional theory (DFT) suggests that mismatch of the density of states (DOS) is responsible for these novel switching behaviors.
Superhydrophobicity of Boron Nitride Nanotubes Grown on Silicon Substrates
BNNTs-Superhydrophopicity-Langmuir2009
Langmuir, good images, SEM, Scanning Electron Microspy
Effective growth of boron nitride nanotubes by thermal chemical vapor deposition
good images, quartz, coating
Patterned Growth of Long and Clean Boron Nitride Nanotubes on Substrates
Electron Microscopy, Argonne National Laboratory, good images, coating
Noncovalent Functionalization of Boron Nitride Nanotubes with Poly(p-phenylene-ethynylene)s and Polythiophene
Publications, Article, Applied Materials and Interfaces, polythiophene, poly(p-phenylene-ethynylene), fluorescence
Low Temperature Growth of Boron Nitride Nanotubes on Substrates
Low temperature, good images, Nano Letters
Origins of Thermodynamically Stable Superhydrophobicity of Boron Nitride Nanotubes Coatings
Langmuir, Publications, good images, Hydrophobic, coating
Recent Advances in Boron Nitride Nanotubes
Nanotubes, good images, hydrophobic, coatings, applications