Solid State Communications 136 (2005) 342–345
Fe nanowire encapsulated in boron nitride nanotubes
a, a
*
, Takeo Oku , Masahiko Nishijima
b
Naruhiro Koi
a
Institute of Scientific and Industrial Research, Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan
b
Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
Received 8 July 2005; accepted 9 August 2005 by H. Akai
Available online 25 August 2005
Abstract
Boron nitride (BN) nanotubes, nanohorns, nanocoils were synthesized by annealing Fe
4
N and B powders at 1000 8C for 1 h in
nitrogen gas atmosphere. Especially, Fe-filled BN nanotubes were produced, and investigated by high-resolution electron
microscopy, high-angle annular dark-field scanning transmission electron microscopy, electron diffraction and energy
dispersive X-ray spectroscopy, which indicates that the [110] of Fe is parallel to the BN nanotube axis. Formation mechanism of
Fe-filled BN nanotube was speculated based on these results.
q 2005 Elsevier Ltd. All rights reserved.
PACS: 61.46. CW; 68.37. Lp; 81.07. De; 81.10. Aj
Keywords: A. Boron nitride (BN); A. Fe; A. Nanocoil; A. Nanowire; C. High-resolution electron microscopy
1
. Introduction
because it is difficult to exist in directly fabricating BN
nanocable with metal cores to the poor wetting property of
BN to metal.
Several studies have been reported on metal-filled BN
nanomaterials. Nanowires constructed from magnetic
materials, especially Fe, Co and some Fe-based alloys are
of interest, because they are likely to be used in
nanoelectronics devices, magnetic recording media and
biological sensors. However, the oxidation- and corrosion-
resistances of surface are weak point of the metallic
nanowires. BN nanocables are of potential use for nanoscale
electronic devices and nanostructured ceramic materials
because of providing good stability at high temperatures with
high electronic insulation in air [1–13]. Therefore, metal-
filled BN nanomaterials would have significant advantages
for technological application. Although it is reported that Fe-
filled BN nanotube could be achieved [1], they still have
some problems such as little production and low yield
The purpose of the present work is to synthesis Fe-filled
BN nanotube and various BN nanomaterials and to
investigate the morphology of Fe-filled BN nanotube by
high-resolution electron microscopy (HREM), high-angle
annular dark-field scanning transmission electron
microscopy (HAADF-STEM), electron diffraction and
energy dispersive X-ray spectroscopy (EDX). It is possible
to use HAADF-STEM to detect single heavy atoms on
alight support. Scattering is caused by the nucleus and
2
follows roughly a Z dependence. Fe-filled BN nanotubes
could be observed by performing centrifugation. It is
considered that centrifugation is effective in collecting Fe-
filled BN nanotube because density of Fe is higher than that
of BN nanomaterials. Formation mechanism of Fe-filled BN
nanotube was proposed based on these results.
2
. Experimental procedures
*
Corresponding author. Tel.: C81 6 6879 8521; fax: C81 6 6879
522.
E-mail addresses: koi@eco.sanken.osaka-u.ac.jp (N. Koi),
oku@sanken.osaka-u.ac.jp (T. Oku).
8
Fe
Their particle sizes were about 50 and 45 mm, respectively.
4
N and boron powders were used as raw materials.
0038-1098/$ - see front matter q 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.ssc.2005.08.009