Abstract: Adsorption of a boron nitride nanotube (BNNT) was
examined toward ethylacetylene (C4H6) molecule by using density
functional theory (DFT) calculations at the B3LYP/6-31G (d) level,
and it was found that the adsorption energy (Ead) of ethylacetylene
the pristine nanotubes is about -1.60kcal/mol. But when nanotube has
been doped with Si and Al atoms, the adsorption energy of
ethylacetylene molecule was increased. Calculation showed that
when the nanotube is doping by Al, the adsorption energy is about -
24.19kcal/mol and also the amount of HOMO/LUMO energy gap
(Eg) will reduce significantly. Boron nitride nanotube is a suitable
adsorbent for ethylacetylene and can be used in separation processes
ethylacetylene. It is seem that nanotube (BNNT) is a suitable
semiconductor after doping, and the doped BNNT in the presence of
ethylacetylene an electrical signal is generating directly and therefore
can potentially be used for ethylacetylene sensors.
Abstract: Radiation shielding is an obstacle in long duration space exploration. Boron Nitride Nanotubes (BNNTs) have attracted attention as an additive to radiation shielding material due to B10’s large neutron capture cross section. The B10 has an effective neutron capture cross section suitable for low energy neutrons ranging from 10-5 to 104 eV and hydrogen is effective at slowing down high energy neutrons. Hydrogenated BNNTs are potentially an ideal nanofiller for radiation shielding composites. We use Molecular Dynamics (MD) Simulation via Material Studios Accelrys 6.0 to model the Young’s Modulus of Hydrogenated BNNTs. An extrapolation technique was employed to determine the Young’s Modulus due to the deformation of the nanostructure at its theoretical density. A linear regression was used to extrapolate the data to the theoretical density of 2.62g/cm3. Simulation data shows that the hydrogenated BNNTs will experience a 11% decrease in the Young’s Modulus for (6,6) BNNTs and 8.5% decrease for (8,8) BNNTs compared to non-hydrogenated BNNT’s. Hydrogenated BNNTs are a viable option as a nanofiller for radiation shielding nanocomposite materials for long range and long duration space exploration.
Abstract: Density functional theory (DFT) calculations were
performed to compute nitrogen-14 and boron-11 nuclear quadrupole
resonance (NQR) spectroscopy parameters in the representative
model of armchair boron nitride nanotube (BNNT) for the first time.
The considered model consisting of 1 nm length of H-capped (5, 5)
single-wall BNNT were first allowed to fully relax and then the NQR
calculations were carried out on the geometrically optimized model.
The evaluated nuclear quadrupole coupling constants and asymmetry
parameters for the mentioned nuclei reveal that the model can be
divided into seven layers of nuclei with an equivalent electrostatic
environment where those nuclei at the ends of tubes have a very
strong electrostatic environment compared to the other nuclei along
the length of tubes. The calculations were performed via Gaussian 98
package of program.