Raman Spectroscopy Of Boron Nitride Nanotubes And Boron Nitride — Carbon Composites (original) (raw)
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We report the structures and the nonresonant Raman spectra of hybrid systems composed of carbon fullerenes (C 60 and C 70) encased within single walled boron nitride nanotube. The optimal structure of these systems are derived from total energy minimization using a convenient Lennard-Jones expression of the van der Waals intermolecular potential. The Raman spectra have been calculated as a function of nanotube diameter and fullerene concentration using the bond polarizability model combined with the spectral moment method. These results should be useful for the interpretation of the experimental Raman spectra of boron nitride nanotubes encasing C 60 and C 70 fullerenes.
Synthesis and Raman characterization of boron-doped single-walled carbon nanotubes
Carbon, 2005
A systematic study was carried out to dope single-walled carbon nanotube (SWNT) bundles with varying amounts of boron using the pulsed laser vaporization technique. Targets containing boron concentrations ranging from 0.5 to 10 at.% boron were prepared by mixing elemental boron with carbon paste and the Co/Ni catalysts. The laser-generated products that were obtained from these targets were characterized by high resolution transmission electron microscopy, electron energy loss spectroscopy (EELS), thermoelectric power (TEP) measurements, and Raman scattering experiments. Electron microscopy and Raman studies revealed that the presence of various levels of boron concentration in the target strongly affected the products that were prepared. SWNTs were found in the products prepared from targets containing up through 3 at.% boron, and high resolution EELS estimated that less than 0.05-0.1 at.% boron is present in the SWNT lattice. The absence of SWNT bundles in the products derived from targets containing more than 3 at.% boron implies that the presence of excess boron in the carbon plume severely inhibits the carbon nanotube growth. The overall effect of the boron incorporation primarily leads to: (i) a systematic increase in intensity of the disorder-induced band (D-band) upon boron doping, with increasing D-band intensity observed for higher doping levels, (ii) a systematic downshift in the G 0 -band frequency due the relatively weaker C-B bond, and (iii) a non-linear variation in the RBM and G 0 -band intensities which is attributed to shifts in resonance conditions in the doped tubes. Resonant Raman spectroscopy thus provides large changes in the intensity of prominent features even when the dopant concentration is below the detectable limit of EELS (0.05-0.1 at.%). Thermoelectric power data also provide complementary evidence for the presence of a small boron concentration in the SWNT lattice which transforms the SWNTs into a permanently p-type material.
Raman active modes of single-wall boron nitride nanotubes inside carbon nanotubes
OAJ Materials and Devices, 2018
The structure of boron–nitride nanotubes (BNNTs) is very similar to that of CNTs, and they exhibit many similar physical and chemical properties. In particular, a single walled boron nitride nanotube (BNNT) and a single walled carbon nanotube (CNT) have been reported. The spectral moment’s method (SMM) was shown to be a powerful tool for determining vibrational spectra (infrared absorption, Raman scattering and inelastic neutron-scattering spectra) of harmonic systems. This method can be applied to very large systems, whatever the type of atomic forces, the spatial dimension, and structure of the material. The calculations of vibrational properties of BNNT@CNT double-walled hybrid nanostructures are performed in the framework of the force constants model, using the spectral moment's method (SMM). A Lennard–Jones potential is used to describe the van der Waals in-teractions between inner and outer tubes in hybrid systems. The calculation of the BNNT@CNT Raman active modes as a fu...
Raman characterization of boron-doped multiwalled carbon nanotubes
Applied Physics Letters, 2002
We present first-and second-order Raman spectra of boron-doped multiwalled carbon nanotubes. The Raman intensities are analyzed as a function of the nominal boron concentration. The intensities of both the D mode and the high-energy mode in the first-order spectra increase with increasing boron concentration, if normalized with respect to a second-order mode. We interpret this result as an indication that the high-energy mode in carbon nanotubes is defect-induced in a similar way as the D mode. Based on this result, we provide a preliminary quantitative relation between the boron concentration and the Raman intensity ratios.
Raman Spectroscopy of Single-Wall Boron Nitride Nanotubes
Nano Letters, 2006
Raman excitation in the UV (229 nm) provides preresonant conditions, allowing the identification of the A 1 tangential mode at 1370 cm -1 . This is 5 cm -1 higher than the E 2g mode in bulk h-BN. Ab initio calculations show that the lower frequency of bulk h-BN with respect to large diameter nanotubes and the single sheet of h-BN is related to a softening of the sp 2 bonds in the bulk due to interlayer interaction.
Raman spectroscopy study of heat-treated and boron-doped double wall carbon nanotubes
Physical Review B, 2009
We performed Raman spectroscopy experiments on undoped and boron-doped double walled carbon nanotubes ͑DWNTs͒ that exhibit the "coalescence inducing mode" as these DWNTs are heat treated to temperatures between 1200°C and 2000°C. The fact that boron doping promotes DWNT coalescence at lower temperatures allowed us to study in greater detail the behavior of first-and second-order Raman modes as a function of temperature with regard to the coalescence process. Furthermore, by using various excitation laser energies we probed DWNTs with different metallic ͑M͒ and semiconducting ͑S͒ inner and outer tubes. We find that regardless of their M and S configurations, the smaller diameter nanotubes disappear at a faster rate than their larger diameter counterparts as the heat treatment temperature is increased. We also observe that the frequency of the G band is mostly determined by the diameter of the semiconducting layer of those DWNTs that are in resonance with the laser excitation energy. Finally, we explain the contributions to the GЈ band from the inner and outer layers of a DWNT.
2020 1st International Conference on Innovative Research in Applied Science, Engineering and Technology (IRASET), 2020
Polarized Raman spectra of single-walled carbon nanotube (SWCNT) inside single-walled boron nitride nanotube (SWBNNT) are calculated as a function of their diameter and chirality. The spectral moment’s method was shown to be a powerful tool for determining vibrational spectra (infrared absorption, Raman scattering and inelastic neutron-scattering spectra) of harmonic systems. The calculations of vibrational properties of double-walled hybrid nanostructures SWCNT inside SWBNNT (SWCNT@SWBNNT) are performed in the framework of the force constants model, using the spectral moment’s method (SMM). To describe the Van der Waals interactions between inner and outer tubes in hybrid systems, we used a Lennard-Jones potential. These predictions are useful to interpret the experimental data.
Raman spectrum of single-walled boron nitride nanotube
Physica E: Low-dimensional Systems and Nanostructures, 2009
Using the spectral moments method, the calculations of the Raman spectra of single-walled boron nitride nanotubes (SW-BNNTs) were performed in the framework of the force constants model. Spectra were computed for chiral and achiral nanotubes for different diameters and lengths. The Raman scattering intensities were determined using the bond-polarizability model and a good agreement with group theory analysis was found. We show that the modes in the low frequency region are very sensitive to the nanotube diameter variation, whereas the ones associated to the tangential region are chirality dependent. The number of Raman active modes, their frequencies, and intensities depend on the length of the nanotube.
Optical and Vibrational Properties of Boron Nitride Nanotubes
B-C-N Nanotubes and Related Nanostructures, 2009
• Diameter-dependence of Raman and IR active modes • Raman intensities • Experimental results on Raman and IR spectroscopy 6. Summary and conclusions ABSTRACT As for carbon nanotubes, optical and vibrational spectroscopy -in particular Raman and luminescence spectroscopy -play an important role for the characterization of BN nanotubes. In this chapter we review, from a theoretical view point, the different spectroscopic techniques that are currently used for BN-nanotubes and make a close link with available experimental data. We summarize experimental and theoretical data on optical absorption spectroscopy, luminescence spectroscopy, electron-energy loss spectroscopy, Raman spectroscopy and infrared absorption spectroscopy. The combination of all those methods allows for a fairly complete characterization of the electronic structure and the vibrational properties of BN tubes. Possible applications in optoelectronic devices are briefly discussed.
physica status solidi (b), 2009
Substitutional doping on single-wall an on multi-wall carbon nanotubes is possible by adding new atoms during the growing process. In this work we analyze the changes in the Raman spectra of SWNT samples substitutionaly doped with boron, nitrogen, and phosphorous. We find that small amounts of dopants are not enough to change the frequency of the tangential G mode, but there is a doping-dependent shift in v G when the P-doped SWNTs are measured at high laser power, indicating that doping can change the thermal properties of SWNT bundles. This result seems to hold also for B-doped samples, but not for N-doped SWNTs, showing a different behavior for donors (P-and N-doping). The I D /I G ratio analysis to provide information about the doping level in the SWNT samples is also discussed.