2005 APS March Meeting
Monday–Friday, March 21–25, 2005;
Los Angeles, CA
Session U27: Focus Session: Carbon Nanotubes: Growth
8:00 AM–11:00 AM,
Thursday, March 24, 2005
LACC
Room: 501C
Sponsoring
Unit:
DMP
Chair: Vera Sazanova, Cornell University
Abstract ID: BAPS.2005.MAR.U27.7
Abstract: U27.00007 : Highly nitrogen and boron doped nanotubes: a route to synthesis and study of their properties by spatially resolved EELS
9:12 AM–9:48 AM
Preview Abstract
Abstract
Author:
Annick Loiseau
(LEM, Cnrs-Onera, Chatillon, France)
Doping C-nanotubes with B and/or N is expected to be a particular
interesting way for tuning electronic and mechanical properties. BN
nanotubes are predicted to behave as insulators whereas B(N) doped
C-nanotubes are expected to be metallic, independent of their structure. In
this framework, we have developped, both at Onera and GDPC, original routes
to the synthesis of BN singlewall nanotubes (BN-SWNTs) and to highly doped
nitrogen multi wall nanotubes (CN$_{x}$-MWNTs).
CN$_{x}$-MWNTs were produced by a CVD method, using an aerosol injector
which sprays in the reactor, heated at 950\r{ }C, a liquid mixture of
organic compounds with a controlled N/C ratio and suitable metal complexes
as the catalyst precursors$^{1}$. This procedure leads to dense amounts of
MWNTs with controlled N/C ratios which can exceed 15-20{\%} in average. Upon
doping, tubes get a characteristic compartimentalized structure with a
reduced number of layers identified in transmission electron microscopy.
Using spatially resolved electron energy loss spectroscopy (EELS), N is
found to be preferentially localized in inner layers and in the
compartiments where the concentration can exceed 40 at.{\%}. Structure of
core losses in EELS reveals a high dependance of the N environment to the
local concentration :chemical bonding of N can be graphitic, pyridinic or
pyrrolic, this latter case being found for highest N concentrations.
Relationships between these structural properties and formation mechanism
will be discussed$^{2}$.
BN-SWNTs are issued from the vaporization of a BN target by a continuous
CO$_{2}$ laser under a N$_{2}$ atmosphere$^{3}$. We present here the first
investigation on their electronic properties by two ways: first, analysis of
the dielectric response of low loss EELS recorded on individual tubes
provides the first identification of plasmons and of interband transitions
in these tubes and the first measure of their gap found to be close to
5.8eV$^{4}$. Second, optical absorption spectra measured on macroscopic
samples strongly suggest the existence of a Frenkel exciton with a binding
energy in the 1eV range$^{5}$.
1-M. Glerup et al Chem. Commun 2542 (2003).
2-M. Castignolles et al submitted to Phys. Rev B (2005)
3- R. Lee et al, Phys. Rev. B Rapid Comm 64, 121405-1 (2001)
4-R. Arenal et al, submitted to Phys. Rev. Lett. (2005)
5-J.S. Lauret et al, Phys. Rev. Lett. (2005) in press.
Coauthors: M. Castignolles$^{1,2}$, R. Arenal$^{1}$, O. St\'{e}phan$^{3}$,
M. Glerup$^{2,4}$,$^{ 1 }$LEM, CNRS-ONERA, Ch\^{a}tillon, France, $^{2
}$GDPC, Universit\'{e} Montpellier II, France, $^{3 }$LPS, Universit\'{e}
Paris-Sud, Orsay, France, $^{4}$GHMFL, MPI-CNRS, Grenoble, France.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2005.MAR.U27.7