Bundle of nanobelts up to 4 cm in length: One-step synthesis and preparation of titanium trisulfide (TiS3) nanomaterials

Article abstract of DOI:10.1002/ejic.200500805

One-dimensional (1D) titanium trisulfide (TiS₃) nanobelt bundles up to 4 cm in length have been successfully synthesized through an easy and common chemical vapor transition (CVT) process. The as-synthesized samples were characterized by X-ray powder diffraction (XRD), polarized light microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). All microscopic observations indicated a belt-like morphology. Powder XRD patterns showed that TiS₃ crystallized in the monoclinic system with a = 4.958(1) A, b = 3.393(1) A, c = 8.793(3) A and β = 97.27(5)°. TEM images revealed a nanostructure with an interplanar spacing of 0.87 nm. The ED pattern and HRTEM images confirmed the [014] elongated direction and the [001] dilated direction of the bundle of TiS₃ nanobelts. Its tensile strength (TS) was further examined with a universal testing machine with 20 N as the biggest strength: the maximum stress and the break strain were 111.027 MPa and 97.1 %, respectively. Because the TiS ₃ nanocrystals are up to 4 cm in length and flexible enough to be cut into small pieces, they should be used directly in electrical and electronic applications. Also, these nanomaterials are synthesized and prepared by a simple one-step process. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.

Full text of DOI:10.1002/ejic.200500805

SHORT COMMUNICATION
DOI: 10.1002/ejic.200500805
Bundle of Nanobelts Up to 4 cm in Length: One-Step Synthesis and
Preparation of Titanium Trisulfide (TiS ) Nanomaterials
3
[a]
[a]
[a]
[a]
[b]
Jingjing Ma, Xiaoyang Liu,* Xuejing Cao, Shouhua Feng, and Michael E. Fleet
Keywords: One dimensional / Nanostructures / Layered compounds / Titanium / Sulfides / CVT / One-step synthesis
One-dimensional (1D) titanium trisulfide (TiS
bundles up to 4 cm in length have been successfully synthe-
sized through an easy and common chemical vapor transition
3
) nanobelt
firmed the [014] elongated direction and the [001] dilated di-
rection of the bundle of TiS nanobelts. Its tensile strength
(TS) was further examined with a universal testing machine
with 20 N as the biggest strength: the maximum stress and
the break strain were 111.027 MPa and 97.1%, respectively.
3
(CVT) process. The as-synthesized samples were charac-
terized by X-ray powder diffraction (XRD), polarized light
microscopy, scanning electron microscopy (SEM), and trans-
mission electron microscopy (TEM). All microscopic observa-
tions indicated a belt-like morphology. Powder XRD patterns
3
Because the TiS nanocrystals are up to 4 cm in length and
flexible enough to be cut into small pieces, they should be
used directly in electrical and electronic applications. Also,
these nanomaterials are synthesized and prepared by a sim-
ple one-step process.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2006)
3
showed that TiS crystallized in the monoclinic system with
a = 4.958(1) Å, b = 3.393(1) Å, c = 8.793(3) Å and β = 97.27(5)°.
TEM images revealed a nanostructure with an interplanar
spacing of 0.87 nm. The ED pattern and HRTEM images con-
2
I. Introduction
ture, and increases up to approximately 100 cm /V at 100 K,
[
15]
and then drops at lower temperatures. Thin films of TiS3
Recently, there is a growing interest in the synthesis,
characterization, and application of one-dimensional (1D)
nanomaterials such as nanobelts, nanowires, etc. because of
their low dimensionality and high aspect ratio, as well as
their unusual physical properties. The synthesis and func-
tionality of 1D nanomaterials have become one of the most
highly energized research areas. During the past two dec-
ades, various sulfide nanomaterials have been synthe-
have been prepared by thermal chemical vapor deposition
[16]
(
CVD), by reacting TiCl and a series of sulfur sources,
4
but the nanoscale synthesis of TiS has few successful re-
3
sults reported. Only Dong-Kyun Seo synthesized the TiS3
material in the same size with TiO powder and the mix-
2
tures of boron and sulfur as starting materials by a solid-
[17]
gas metathetical reaction, but there was neither SEM nor
TEM image to indicate its nanosize. Furthermore, the bo-
ron powder could not adsorb all the oxygen completely dur-
ing this oxidation–deoxidization process, and the remained
[
1–12]
sized.
However, the preparation of sulfide nanobelts re-
mains poorly studied, and only a few successful examples
have been reported. For example, ZnS nanobelts with
wurtzite structure have been prepared by simple thermal
evaporation of ZnS powder in the presence of Au catalysts
TiO would reduce the purity of the sample, some other
2
peaks of the mixture from its XRD pattern also confirmed
that.
[
13]
at 970 °C.
sized in the mixed solution of PbCl and Na S O .
PbS nanobelts have been successfully synthe-
It is well known that the synthesis and preparation gen-
erally require two separate steps in the fabrication of func-
tional materials, e.g., firstly the phase is obtained in powder
form using different synthesis methods, and then the pow-
der product is processed into different functional forms ac-
cording to specific applications, with hot pressing being the
most common method used to work the powders. However,
for nanomaterials, the particle size increases when the nano-
powders are hot-pressed, which results in the loss of physi-
cal properties associated with the small-size effect (high spe-
cific surface area, surface conductivity, etc.). The retention
of small particle size while processing the powders into dif-
ferent shapes is a very important issue in the field of nano-
materials. We presently report the synthesis and preparation
[
14]
2
2
2
3
Titanium trisulfide TiS is of interest to us because of its
3
potential application in CuO-based cathodes of non-aque-
ous alkali metal batteries. Measurements of the electrical
conductivity and the Hall coefficient at 15–300 K and of
the thermal EMF at 80–400 K indicate that TiS is semi-
3
conducting with extrinsic n-type conductivity. The mobility
2
of the carriers is approximately 30 cm /V at room tempera-
[
[
a] State Key Laboratory of Inorganic Synthesis and Preparative
Chemistry, College of Chemistry, Jilin University,
2
699 Qianjin Street, Changchun, 130012, P. R. China
Fax: +86-431-5168316
E-mail: liuxy@jlu.edu.cn
b] Department of Earth Sciences, University of Western Ontario,
London, Ontario N6A 5B7, Canada
of high-purity TiS with nanobelt structure by an easy and
3
Eur. J. Inorg. Chem. 2006, 519–522
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
519

J. Ma, X. Liu, X. Cao, S. Feng, M. E. Fleet
SHORT COMMUNICATION
common one-step CVT process, which yields a product that
can be used directly in electrical and electronic applications.
II. Results and Discussion
The products were characterized by X-ray diffraction
(
XRD, with a SIEMENS D5005 diffractometer with a
graphite monochromator), scanning electron microscopy
SEM JEOL.LTD JSM-6700F), transmission electron mi-
(
croscopy (TEM, Jeol Ltd., JEM-3010), polarized-light mi-
croscopy (Olympus BX51), universal testing machine (Shi-
madzu AG-I).
The XRD pattern of the bulk samples (e.g., Figure 1)
3
Figure 2. The appearance of the bundle of TiS nanobelts in polar-
was consistent with pure TiS (JCPDS No. 36–1337). The ized-light microscopy (Olympus BX51). a) and b) show the dark
3
product crystallized in the monoclinic system with a = grey belt-like appearance. c) and d) reveal the layered microstruc-
ture.
4
9
.958(1) Å, b = 3.393(1) Å, c = 8.793(3) Å and β =
7.27(5)°. The structure calculations were optimized by le-
ast-squares refinement. The diffraction peaks were sharp
and strong, confirming that the products were well crys-
tallized. This XRD pattern also proved that the [001] direc-
tion should be the direction of growth of TiS nanobelts
3
bundle either elongated direction or dilated direction. Using
polarized-light microscopy, the TiS crystals were seen to
3
be dark grey with a metallic shine and belt-like habit (Fig-
ure 2). The nanocrystals were up to 4 cm in length and,
thus, apparently suitable without further treatment as func-
tional material in electrical devices. Figure 2 (c and d) reveal
a layered structure in agreement with the strong preferred
orientation indicated by the bulk XRD pattern (Figure 1)
and the habit of TiS crystals deduced in previous stud-
3
ies.[
18,19]
Figure 3. Low-magnification SEM images of TiS nanobelt bundles
3
synthesized by a simple CVT process of Ti and S at 600 °C; a) is
taken from the centre of a TiS
3
nanobelt bundle; b) shows the typi-
cal appearance of TiS
massive nanobelts.
3
nanobelt bundles; c) and d) show details of
up to 4 cm were first comminuted by grinding in ethanol,
then the mixed solution was pulsed by ultrasonic cleaner
for ca. 10 min. In order to sample the smallest size fraction
of TiS crystals, the clear solution on top of the sedimented
3
column was pipetted onto a holey carbon grid, and the eth-
anol allowed to evaporate. Typical TEM images at low mag-
nification (Figure 4, a and b) show that the ground crystal
products are nanobelts, and that the yield of nanobelts is
quite high (Ͼ95%). The selected-area electron diffraction
pattern taken from a single TiS nanobelt confirms the sin-
3
3
Figure 1. Bulk XRD pattern of the bundle of TiS nanobelts. The
numbers above the peaks are the Miller indices for the monoclinic
structure.
gle-crystal nature of the sample and can be indexed on a
monoclinic unit cell, consistent with the powder XRD re-
sults presented above (JCPDS No. 36–1337). The [014] di-
The morphology of the nanobelt crystals was further in- rection of the ED pattern is parallel to the elongated axis
vestigated by SEM. A typical SEM image of the TiS prod- of the belt, showing that the elongated growth might occur
3
ucts (Figure 3, a) shows smooth laminar crystal faces and along the [014] direction. Furthermore, the [001] direction
a layered structure. Figure 3 (b, c and d), shows a more of the ED pattern is parallel to the dilated axis of the belt,
massive habit with individual TiS nanobelts up to 100 μm showing that the dilated growth might occur along the [001]
3
in length.
direction which corresponds to the XRD result. High-reso-
TEM images (Figure 4) provide further insight into the lution TEM images (Figure 4, c and d) show that the nano-
morphology of these materials. TiS nanobelts with length belts are single crystals and free of dislocations and defects.
3
520
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Eur. J. Inorg. Chem. 2006, 519–522

3
One-Step Synthesis and Preparation of TiS Nanomaterials
SHORT COMMUNICATION
From Figure 4 (c), we can see that the nanobelts are struc- ulated by broken bonds, although the strong bonds of the
turally uniform with an interplanar spacing of 0.87 nm; it monoclinic TiS structure remain in tact. The nanobelts
3
should be elongated along the [014] direction and dilated tend to separate into 1D needles by cleavage along (001),
along the [210] direction which is consonant with the ED which requires the breaking of the weak van der Waals’
pattern. The TiS nanobelts were not sensitive to electron bonds. On the basis of this orientational relationship, one
3
beam irradiation during the HRTEM investigation.
would expect that the lattice fringes of Figure 4 (c and d)
should correspond to the interlayer spacing d001
(
0.8706 nm). The 1D TiS needles should get widen layer
3
by layer along the [100] direction which is consistent with
the HRTEM results.
Figure 4. TEM and HRTEM images of the TiS
ing details of their geometry; a) and b) are images of several over-
lapped TiS nanobelts, (inset) The corresponding electron diffrac-
3
nanobelts reveal-
3
tion pattern confirms the single-crystal nature of the sample and
can be indexed to a monoclinic unit cell consistent with the XRD
results presented above; c) and d) are HRTEM images of a TiS
3
nanobelt, showing that the nanobelts are single crystals and free
from dislocations and defects, also, the nanobelts are structurally
uniform with an interplanar spacing about 0.87 nm.
Figure 5. Structure of titanium trisulfide TiS
ture of titanium trisulfide TiS shows that the Ti atom is in irregu-
lar eightfold coordination with S atoms. Six shorter Ti–S distances
(2.45 to 2.49 Å) form TiS trigonal prisms, which are linked by
unit are present as a single-bonded disulfide ion (S22–; S–S shared faces into an infinite chain parallel to the b-axis, making
the structure quasi one-dimensional; (b) schematic pattern of the
layer structure of titanium trisulfide (TiS ) shows that the crystals
of TiS are elongated in the b-axis direction and that the layer sur-
3
; (a) monoclinic struc-
3
Figure 5 shows that in the structure of monoclinic tita-
nium trisulfide TiS , two of the three S atoms per formula
3
6
2– [16]
=
2.04 Å), and the third S atom is formally sulfide (S ).
3
The Ti atom is in irregular eightfold coordination with S
atoms. Six shorter Ti–S distances (2.45 to 2.49 Å) form TiS6
3
face is (001). Also, the crystals have a cleavage parallel to (100).
trigonal prisms, which are linked through shared faces into
an infinite chain parallel to the b-axis, that makes the struc-
In order to prove that these bundles of TiS are not ex-
3
ture quasi one-dimensional. Neighboring chains are offset tremely fragile, we use an universal testing machine with
by b/2 and connected laterally by longer Ti–S bonds (2.63 20 N as the biggest strength to examine the tensile strength
and 2.64 Å) into sheets parallel to the crystal face (001). of this material. Figure 6 showed that the maximum stress
Individual (001) sheets are bounded above and below by a was 111.027 MPa, the break strain 97.1% and the average
layer of disulfide groups, and held together in the resulting stress 100–110 MPa. The maximum stress value of a
two-dimensional structure by only van der Waals’ forces. bundle of TiS is nearly the same with that of aluminum
3
[16,18]
[20]
Extensive bulk and powder XRD
(Figure 1) and (Ϸ 100 MPa),
and much higher than those of some
microfocus single-crystal XRD[ show that the acicular widely used engineering plastics such as PVC (Ϸ 25 MPa),
18]
[
21]
(
needle-shaped) and blade- or belt-like crystals of TiS are poly(propylene) (25.48 MPa)
and poly(vinyl acetate)
elongated in a gradient direction, and that the layer surface (29.4 MPa), even some films used in conducting applica-
i.e., the prominent growth surface) is (001), which is also tion. For example, a poly(p-phenylene) (PPP) film was elec-
3
[
21]
(
concluded from HRTEM images and ED pattern. In ad- trochemically deposited onto a stainless steel electrode sur-
dition, the TiS nanobelts bundle can be broken into 1D face by direct oxidation of benzene in BF –diethyl ether
3
3
needles, having a parting or cleavage parallel to the (100) solution at an applied potential of 1.7 V (vs. Ag/AgCl), and
direction. This parting is believed to be responsible for the the as-grown PPP film had a tensile strength of 53.9–
[
22]
belt-like morphology of the nanocrystals shown in Figure 2 63.7 MPa;
a crystalline polythiophene (Pth) film was
(d) and Figure 4, and requires the severing of the long (2.63 electrochemically deposited onto a nickel substrate from
and 2.64 Å) Ti–S bonds. Thus, the broad surface of the freshly distilled BF –diethyl ether (BFEE) solution contain-
3
nanobelts (Figure 4, a) is a cleavage or parting surface pop- ing 15 mm thiophene, and the crystalline film had a tensile
Eur. J. Inorg. Chem. 2006, 519–522
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
521

J. Ma, X. Liu, X. Cao, S. Feng, M. E. Fleet
SHORT COMMUNICATION
strength of 73.5–83.3 MPa.[23] So we believe these TiS3 was evacuated and sealed, and heated in a horizontal-tube furnace.
The synthesis was achieved by establishing a temperature gradient
nanobelts bundles should be flexible enough to be used in
of 80–100 °C along the tube with the starting mixture at the hot
applications directly.
3
end. TiS fibers were obtained at the cool end when charges were
heated at 600 °C for 15 days. When the temperature was set below
00 °C, the sulfur did not react completely with titanium, and an
6
excess amount of it was deposited at the cool end. Temperatures
above 600 °C tended to produce unwanted powder and crystals of
TiS
sulfur) at 632 °C, 8.95 atm. The optimum reaction duration was
5 days.
2 3 2
: TiS undergoes peritectic decomposition (to TiS + native
1
Acknowledgments
This work was supported by the Natural Sciences Foundation of
China (No. 20471022) and the Natural Sciences and Engineering
Research Council of Canada.
3
Figure 6. Tensile strength (TS) of the TiS nanobelts bundle.
[
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3
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3
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Received: September 13, 2005
Published Online: December 27, 2005
522
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© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2006, 519–522