Silicon Encapsulated Carbon Nanotubes

Abstract

A dual stage process of depositing bamboo-like carbon nanotubes (BCNTs) by hot filament chemical vapor deposition (HFCVD) and coating Si using Radio frequency sputtering (RFS) technique. The films were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and electron field emission studies (EFE). SEM results suggest a dense network of homogeneous silicon-coated BCNTs. From the comprehensive analysis of the results provided by these techniques emerges the picture of Si encapsulated BCNTs.

Surface Structure-Dependent Low Turn-On Electron Field Emission from Polypyrrole/Tin Oxide Hybrid Cathodes

“…For example, the turn-on field for the GaS nanohorns is 4.2 V/μm, for the aligned CdS nanowires, it is ∼7.8 V/μm, for the multipods, it is ∼7.2 V/μm, for the TiO 2 nanotip array, it is ∼9.4 V/μm, for the nanotube, it is ∼34 V/μm, for the ZnS nanobelts, it is ∼3.8 V/μm, for the ZnO nanowires, it is∼5 V/μm, for the nanonails, it is ∼7.9 V/μm, and for the nanopencils, it is 7.2 V/μm . The turn-on field ∼1.3 V/μm for the PPy/SnO 2 p–n junctions is also less than the electric field observed in different carbon nanostructures such as UNCD (5.6 V/μm), CNTs [(2.3 V/μm), (1.55 V/μm)], UNCD/CNTs (4.9 V/μm), CNT/ZnO films (1.3 and 2.5 V/μm), UNCD-decorated silicon nanowires (3.7 V/μm), GS (4.4 V/μm), GS/CsI (2.5 V/μm), MWCNTs/CsI (3.2 V/m), and various other nanostructures of carbon. − The turn-on field of the prepared p–n junction in PPy is also less than or equal to the MWCNT/PPy nanocomposite (1.4 V/μm) and PPy/tetrabutylammonium-hexafluorophosphate (PPy/TBAPF 6 ) nanowires (3.5 V/μm) . The electron density is strongly dependent upon the work function (Φ) and the field-enhancement factor (β), and the value of β can be obtained from the F–N plots of ln­( J / E 2 ) versus 1/ E as shown in Figure d by considering that Φ is known.…”

“…The electron density is strongly dependent upon the work function (Φ) and the field-enhancement factor (β), and the value of β can be obtained from the F–N plots of ln­( J / E 2 ) versus 1/ E as shown in Figure d by considering that Φ is known. The straight lines between the ln­( J / E 2 ) and 1/ E curves suggest that the electrons are emitted via the cold cathode emission process determined by the barrier tunneling and quantum mechanical processes. − ,− The field-enhancement factors (β) have been evaluated for both samples from the slopes of F–N plots by using the relation , where d is the thickness of spacer. The value of the field-enhancement factor has been calculated from the slope of F–N plots for both the pure and doped PPy samples and are found to be 2142.24 and 5665.45, respectively, which indicates that the PPy/SnO 2 p–n junctions have the higher field-enhancement factor as compared to the PPy and can be attributed to the emission of electrons from the sp 2 -hybridized conjugated structure of PPy assisted with SnO 2 doping and the emission directly from PPy via the higher local electric field.…”

Dispersion of SiC coated MWCNTs in PEI/silicone rubber blend and its effect on the thermal and mechanical properties

“…The two broad peaks in the Si 2p spectra were resolved into three peaks that corresponds to the binding energy of 100.4, 101.0, and 102.6 eV. The first two peaks correspond to the Si doublet and the third peak corresponds to the SiC 21. In case of C 1s the spectrum was resolved into two peaks centered around 283.6 and 284.5 eV.…”