One convenient synthesis route to boron nitride nanotube

Article abstract of DOI:10.1016/j.ssc.2005.01.011

We describe one convenient synthesis route to boron nitride (BN) nanotube by the reaction of boron powder, iron oxide, and ammonium chloride at 600 °C for 12 h. Characterized by XRD, FTIR, XPS, TEM and SAED, the composition and morphology of the products are confirmed. The possible reaction mechanism is also discussed.

Full text of DOI:10.1016/j.ssc.2005.01.011

Solid State Communications 133 (2005) 621–623
www.elsevier.com/locate/ssc
One convenient synthesis route to boron nitride nanotube
a
Peijun Cai , Luyang Chen , Liang Shi , Zeheng Yang , Aiwu Zhao , Yunle Gu ,
a
a
a
a
a
a
Tao Huang , Yitai Qian
a,b,
*
a
Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, People’s Republic of China
b
Structure Research Laboratory, University of Science and Technology of China, Hefei, Anhui 230026, People’s Republic of China
Received 8 January 2005; accepted 10 January 2005 by P. Sheng
Available online 19 January 2005
Abstract
We describe one convenient synthesis route to boron nitride (BN) nanotube by the reaction of boron powder, iron oxide, and
ammonium chloride at 600 8C for 12 h. Characterized by XRD, FTIR, XPS, TEM and SAED, the composition and morphology
of the products are confirmed. The possible reaction mechanism is also discussed.
q 2005 Elsevier Ltd. All rights reserved.
PACS: 81.05.Je
Keywords: A. Boron nitride; A. Nanotube; B. Synthesis
1
. Introduction
nitriding of MgB
ively [8].
2 4 4 3
with NH Cl and NH Cl–NaN , respect-
Boron nitride (BN) has received considerable attention
Here, we report a convenient chemical route to
synthesize BN nanotube employed ammonium chloride as
nitrogen source. The reaction is carried out in an autoclave
at 600 8C.
due to its advantageous properties such as extreme hardness,
high thermal conductivity, chemical inertness, transparency
and electrically insulating performance [1,2]. These proper-
ties make BN an interesting material for many applications
such as lubricants, protective and optical coatings, advanced
ceramic composites, and mold release liners [3].
2
. Experimental procedure
Up to now, there have been a series of reports on BN
synthesis, such as the carbothermic reduction of boron oxide
All the reagents used were of analytical-grade purity
purchased from Shanghai Chem. Co.). The manipulations
[
(
4], the direct reaction of boron and nitrogen, pyrolysis of
HBNH) [5], direct nitriding of boron acid with ammonia
(
were carried out in a dry glove box filled with N . In a
3
2
gas [6] or heating the mixture of boron and iron oxide in a
flowing ammonia gas at 1300 8C [7]. Recently, Shi et al.
reported that BN nanocrystalline could be synthesized by
typical procedure, an appropriate amount of B powder
(
2 3 4
0.02 mol), Fe O (0.01 mol) and excess NH Cl (0.1 mol)
were put into a stainless autoclave of 50 ml capacity, then
the autoclave was sealed tightly, heated at 600 8C for 12 h,
then cooled to room temperature naturally. The products
were washed with hydrochloric acid (1 M) and distilled
water to remove impurities. Then, the gray products were
dried in a vacuum at 65 8C for 4 h.
*
Corresponding author. Address: Department of Chemistry,
University of Science and Technology of China, Hefei, Anhui
30026, People’s Republic of China. Tel.: C86 551 3601589; fax:
2
C86 551 3607402.
E-mail address: ytqian@ustc.edu.cn (Y.T. Qian).
The obtained samples were characterized by X-ray
powder diffraction (XRD) on a Rigaku Dmax-gA X-ray
0038-1098/$ - see front matter q 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.ssc.2005.01.011

622
P. Cai et al. / Solid State Communications 133 (2005) 621–623
˚
diffractometer with Cu Ka radiation (lZ1.54178 A). The
morphology of BN nanotube was examined from trans-
mission electron microscopy (TEM) images taken with a
Hitachi H-800 transmission electron microscope. X-ray
photoelectron spectra (XPS) were recorded on a VGESCA-
LAB MKII X-ray photoelectron spectrometer, using non-
a
monochromatized Mg K X-rays as the excitation source.
Raman spectrum was performed at ambient temperature on
a Spex 1403 Raman spectrometer with an argon ion laser at
an excitation wavelength of 514.5 nm. Fourier transform-
ation infrared spectroscopy (FTIR) spectra were obtained
using a Shimadzu IR-400 spectrometer by using pressed
KBr disks.
3
. Results and discussion
Fig. 2. XRD pattern of BN nanotube sample.
Fig. 1 gives the FTIR spectra of the BN nanotube
samples at room temperature. Two strong peaks around
shown in Fig. 4, in which the B1s and N1s core-level regions
are examined. It shows that the sample surface consists of
nitrogen and boron, with binding energies of N1s, and B1s at
K1
1
382 and 784 cm
could be observed clearly, which is
assigned to the B–N stretching vibrations and B–N–B
bending vibrations, respectively. The broad absorbed
3
98.7 and 191.5 eV, respectively. The N1s peak at 398.7 eV
and B1s peak at 191.5 eV indicate BN, in good agreement
with those in the literature [10]. The qualification of the peak
intensities reveals that the atomic ratio of B–N is 1.02:1.00,
which agrees well with the chemical stoichiometric relation
between B and N.
K1
absorption peak at 3391 cm is due to water absorbed on
the sample.
Fig. 2 shows the XRD pattern of the sample. All
reflections can be indexed as hexagonal BN with lattice
˚
constants aZ2.497 and cZ6.685 A, which are close to the
Fig. 5 show the tubular morphologies of the as-prepared
BN products. In Fig. 5(a), we find that most of the BN
nanotubes are flexible and tend to bend. Most of them have
lengths of up to several micrometers. Based on the
observation of TEM, the estimated yield of BN nanotubes
is 50%. Fig. 5(b) shows a typical nanotube. It has inner
diameters of 100 nm and wall thickness of 10 nm. We can
also observe that the nanotube has two obvious open ends
˚
˚
reported values of h-BN (aZ2.510 A, cZ6.690 A) (JCPDS
No. 85-1068). No noticeable peaks of impurities such as
Fe O and B can be detected in the XRD pattern. The
2
3
broadening nature of the XRD peaks indicates that the
particles size of the samples is within nanometer scale.
The Raman spectrum of the samples is shown in Fig. 3.
K1
An active vibration band at about 1368.5 cm
is
correspond to the E2g symmetric vibration mode of BN
9]. Coinciding with that of the XRD and IR analysis, the as-
prepared products are h-BN.
[
indicated by the arrow in Fig. 5(b)]. Typical one is
characterized by its selected area electron diffraction pattern
SAED]. The SAED pattern of one BN nanotube [inset in
Fig. 5(b)] is characteristic of a BN nanotube with a
[
[
The XPS spectra of the as-prepared h-BN sample are
Fig. 1. FTIR spectra of BN nanotube sample.
Fig. 3. Raman spectrum of the samples.

P. Cai et al. / Solid State Communications 133 (2005) 621–623
623
another contrast experiment was carried out with the
procedure similar to that mentioned in the experimental
4
section, in which NH Cl, B powder served as the reactants.
There was no BN obtained. Supported by the above result,
we speculate that Fe O plays a role of catalyst and oxidant.
2
3
In the present route, redox reaction is taken place between
elemental B and Fe to produce B . At the same time,
with the temperature increasing, NH Cl begins to decom-
2
O
3
2 2
O
4
3
pose resulting NH , which contributes nitrogen source. The
product BN occurs from the resultants followed between
B O and NH [11].
2
2
3
4
. Conclusions
In summary, BN nanotubes, with inner diameters of
00 nm, wall thickness of 10 nm and length up to several
1
micrometers are successfully synthesized using boron and
ammonium chloride as the reactants by the aid of iron oxide
at a temperature of 600 8C for 12 h. The product is
characterized with XRD, FTIR, XPS, Raman spectrum
and TEM.
Acknowledgements
This work is supported by the National Science
Foundation of China and the 973 Projects of China.
Fig. 4. XPS spectra of BN nanotube sample.
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The possible reaction mechanism of BN is proposed. To
study the effects of the Fe O on the formation of BN,
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Fig. 5. TEM images showing: (a) several BN nanotubes; (b) a
typical BN nanotube, (inset) SAED pattern on the BN nanotube.
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