Synthesis of α-tellurium dioxide nanorods from elemental tellurium by laser ablation

Article abstract of DOI:10.1016/j.inoche.2003.10.037

Elemental tellurium was evaporated by laser ablation, the vapor of which was condensed and deposited on the surface of the heated glass surface and then formed α-tellurium dioxide nanorods with uniformly size distribution by oxidation in the chamber with hot air atmosphere. TEM images and Electron diffraction (ED) pattern confirm the crystallinity of α-phase tellurium dioxide. The formation process of the nanorods involves a vapor-liquid-solid (VLS) following a chemical oxidation in the hot air atmosphere, in which the low melting point tellurium serves as a liquid-forming reagent.

Full text of DOI:10.1016/j.inoche.2003.10.037

Inorganic Chemistry Communications 7 (2004) 179–181
www.elsevier.com/locate/inoche
Synthesis of a-tellurium dioxide nanorods from elemental
tellurium by laser ablation q
*
Zhi-Yuan Jiang, Zhao-Xiong Xie , Xian-Hua Zhang, Su-Yuan Xie,
Rong-Bin Huang, Lan-Sun Zheng
Department of Chemistry, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University,
Siming Nanlu 422, Xiamen 361005, PR China
Received 30 July 2003; accepted 31 October 2003
Published online: 2 December 2003
Abstract
Elemental tellurium was evaporated by laser ablation, the vapor of which was condensed and deposited on the surface of the
heated glass surface and then formed a-tellurium dioxide nanorods with uniformly size distribution by oxidation in the chamber
with hot air atmosphere. TEM images and Electron diffraction (ED) pattern confirm the crystallinity of a-phase tellurium dioxide.
The formation process of the nanorods involves a vapor–liquid–solid (VLS) following a chemical oxidation in the hot air atmo-
sphere, in which the low melting point tellurium serves as a liquid-forming reagent.
Ó 2003 Elsevier B.V. All rights reserved.
Keywords: Nanorod; Tellurium dioxide; Laser ablation
As a class of optical materials, tellurium oxide (TeO2)
commands interest in terms of fundamental theory and
engineering applications [1–5], for example, TeO2-based
glasses find application in laser devices and nonlinear
optics [6–11]. The a-phase of tellurium dioxide exhibits
excellent acousto-optical properties arising from its
elastic behavior and high birefringence [12–15]. Large
crystals of tellurium dioxide [16] are easy to grow, and
device-quality tellurium dioxide can be grown by the
Czochralski process [2,17]. Recently, it was reported
that nanoparticles of tellurium dioxide can be synthe-
sized by sol–gel process [18]. However, to our knowl-
edge, no one-dimensional nanostructures of tellurium
dioxide have been reported. Herein, we present an ac-
count of the synthesis of nanorods of tellurium dioxide
by using a laser assisted growth route.
High-purity tellurium powder was placed in an un-
stoppered 25 cm quartz tube, which was set vertically in
a tube furnace (4 Â 38 cm) [19]. The 1064 nm pulse-laser
from a Q-switched Nd:YAG system (Quantary DCR
130) of 7 ns pulse width was focused onto the tellurium
powder for about 20 min. During the laser ablation, the
tube was heated to a given temperature. After the laser
ablation, the tube was cooled down to the room tem-
perature and the white material that deposited on the
walls was collected.
At approximately 500 °C of the furnace temperature,
the white deposit consisted almost entirely of nanorods;
moreover, the nanorods were uniformly spread over a
narrow range of diameter (20–80 nm) only and they
grew to several microns long (Fig. 1). The elemental
composition of the nanorods (34.1% Te, 65.9% O) was
measured by the EDX spectrum, indicating the presence
of TeO2. X-ray diffraction of the as-prepared products
was further carried out, which showed that the products
belong to the tetragonal P41212 phase of a-TeO2. In the
diffraction pattern, no possible impurities such as pure
Te can be found.
q Supplementary data associated with this article can be found, in the
online version, at doi:10.1016/j.inoche.2003.10.037.
* Corresponding author. Tel.: +86-592-2185667; fax: +86-592-
2183047.
E-mail address: zxxie@xmu.edu.cn (Z.-X. Xie).
1387-7003/$ - see front matter Ó 2003 Elsevier B.V. All rights reserved.
doi:10.1016/j.inoche.2003.10.037

180
Z.-Y. Jiang et al. / Inorganic Chemistry Communications 7 (2004) 179–181
which consists of a-TeO2 as checked by XRD. An am-
bient temperature of 500 °C appears to be optimal for
the formation of single-crystalline tellurium dioxide
nanorods (see Figs. 1 and 3(c)) as at 600 °C, only mi-
cron-sized crystals were formed instead (Fig. 3(d)).
The model for laser-assisted synthesis, particularly of
nanowires, to explain the growth mechanism involves
the participation of vapor–liquid–solid phases (VLS) in
the growth process [20–22] and the central theme of
VLS growth concerns the existence of a liquid-forming
agent. Indeed, the growth consists of two distinct
stages, the formation/nucleation liquid droplets and the
growth of nanowires from supersaturation droplets.
The present study uses laser to evaporate solid tellu-
rium to its vapor phase. Hot air atmosphere (that is
supplied externally by the furnace) allows the tellurium
vapor firstly to aggregate into nanodroplets on the glass
surface and secondly to give the droplets enough time
for the growth process to complete itself. In the absence
of this external heat, the vapor rapidly condenses to
black elemental tellurium nanoparticles. At a suffi-
ciently high temperature, the tellurium vapor remains
in the droplet phase during which time nanodroplets
can be partially or even completely oxidized. Those
droplets condensing on the glass surface serves as the
nucleating point for the one-dimensional growth of the
nanorods. The relatively low melting point of the ele-
ment parallels that of gallium, which can be conve-
niently evaporated into droplets, that catalyze the
growth of silica nanowires [23] and that of selenium,
which catalyzes the growth of zinc oxide nanowires
[24]. The molten tellurium probably also behaves sim-
ilarly to self-catalyze the growth. This suggestion is
supported by our observation, that when tellurium di-
oxide was used in place of elemental tellurium, nano-
rods were not formed.
Fig. 1. SEM image of the product of laser-ablated tellurium heated in
air at 500 °C.
That the TeO2 nanorods are single crystals is illus-
trated by the high-resolution TEM image of a selected
nanorod with a diameter of 31 nm (Fig. 2(a)). The lattice
planes separated by 0.762 nm in the HRTEM image
(Fig. 2(b)) correspond to the (0 0 1) plane. Those lattice
planes in the perpendicular direction separated by 0.488
nm corresponds to the (1 0 0) plane. The ED pattern
(Fig. 2(c)) also supports the presence of the tetragonal
phase and shows that the long axis of the nanorod (i.e.,
the growth direction) orientates along the [1 0 1] direc-
tion.
When the temperature of the furnace was set to less
than 400 °C, only nanoparticles of elemental tellurium
or partially oxidized tellurium were formed (Fig. 3(a)).
At the temperature of about 450 °C, the melting point of
tellurium, wedge-shaped nanorods appeared (Fig. 3(b)),
Our study shows, that a temperature range (450–
600 °C) must be used for the growth of the TeO2
nanorods by using the laser ablation method, a general
feature of VLS growth, that has been proposed to be
responsible for the mechanism of TeO2 nanorods for-
mation. The temperature range must cover the melting
points of the starting reagents, so that droplets can be
easily formed. At the lower edge of this range, e.g., 450
°C, wedge-shaped nanorods could be found in the
products, the formation of which can be rationalized in
terms of a spheroidization process [25,26], that results
from the well-known tendency of a small-bore cylinder
to grow irregularly under the influence of the effects of
capillary action or surface tension. On the other hand, at
temperatures exceeding 600 °C, the TeO2 nanostructures
might melt and on cooling process the melt formed
micro-size rods (Fig. 3(d)).
The inclusion of a chemical conversion to the VLS
appears to be practical complementary method for the
controlled growth of tellurium dioxide nanorods, having
Fig. 2. (a) TEM image of the tip part of one TeO2 nanorod. (b) En-
larged TEM image. (c) The corresponding electron diffraction pattern.

Z.-Y. Jiang et al. / Inorganic Chemistry Communications 7 (2004) 179–181
181
Fig. 3. TEM images of the products prepared at: (a) 350 °C; (b) 450 °C; (c) 500 °C; (d) 600 °C.
[10] R.V.G. Rao, R. Venkatesh, J. Phys. Chem. Solids 64 (2003) 897.
[11] N. Tamagawa, Y. Benino, T. Fujiwara, T. Komatsu, Opt.
Commun. 217 (2003) 387.
a linear morphology and uniform diameter and the
combination may be easily adapted for the generation of
relatively large quantities such material.
[12] P.A. Thomas, J. Phys. C 21 (1988) 4611.
[13] G.K. White, S.J. Collocott, J.G. Collins, J. Phys.: Condens.
Mater. 2 (1990) 7715.
Acknowledgements
[14] G.J. Edwards, O.R. Gilliam, R.H. Bartram, A. Watterich, R.
Voszka, J.R. Niklas, S. Greulichweber, J.M. Spaeth, J. Phys.:
Condens. Mat. 7 (1995) 3013.
This work is generously supported by the National
Natural Science Foundation of China (Grant Nos.
20021002, 29890210 and 20173046) and the Natural
Science Foundation of Fujian Province (Grant No.
E0310004).
[15] S. Kumaragurubaran, D. Krishnamurthy, C. Subramanian, P.
Ramasamy, J. Cryst. Growth 211 (2000) 276.
[16] J. Leibertz, Krist. Tech. 4 (1969) 221.
[17] A.V. Vinogradov, V.A. Lomonov, Y.A. Pershin, N.L. Sizova,
Cryst. Rept. 47 (2002) 1036.
[18] S. Coste, P. Thomas, A. Lecomte, J.C. Champarnaud-Mesjard, R.
ꢀ
Guinebretiee, A. Dauger, Phys. Chem. Glasses 43C (2002)
References
405.
[19] Z.Y. Jiang, Z.X. Xie, S.Y. Xie, X.H. Zhang, R.B. Huang, L.S.
Zheng, Chem. Phys. Lett. 368 (2003) 425.
[1] J.C. Champarnaud-Mesjard, S. Blanchandin, P. Thomas, A.
Mirgorodsky, T. Merle-MeÕjean, B. Frit, J. Phys. Chem. Solids 61
(2000) 1499.
[20] E. Braun, Y. Eichen, U. Sivan, G. Ben-Yoseph, Nature 391 (1998)
775.
[21] J. Sloan, D.M. Wright, H.G. Woo, S. Bailey, G. Brown, A.P.E.
York, K.S. Coleman, J.L. Hutchison, M.L.H. Green, Chem.
Commun. (1999) 699.
[2] C. Neamtu, A. Darabont, E. Surducan, G. Borodi, J. Opt. Adv.
Mater. 2 (2000) 487.
[3] Y. Tanaka, M. Takigahira, S.I. Tamura, Phys. Rev. B 66 (2002)
075409.
[22] M.S. Gudiksen, J.F. Wang, C.M. Lieiber, J. Phys. Chem. B 105
(2001) 4062.
[4] L.A Kappers, O.R. Gilliam, R.H. Bartram, A. Watterich,
I. Foldvari, Radiat. Eff. Defect. Solids 157 (2002) 671.
[5] K. Arshak, O. Korostynska, Microelectron. Int. 19 (2002) 30.
[6] R. El-Mallawany, Mater. Chem. Phys. 53 (1998) 93.
[7] F. Torres, Y. Benino, T. Komatsu, C. Lavelle, J. Mater. Sci. 36
(2001) 4961.
[23] Z.W. Pan, Z.R. Dai, C. Ma, Z.L. Wang, J. Am. Chem. Soc. 124
(2002) 1817.
[24] Y.C. Kong, D.P. Yu, B. Zhang, W. Fang, S.Q. Feng, Appl. Phys.
Lett. 78 (2001) 407.
[25] H.Y. Peng, Z.W. Pan, L. Xu, X.H. Fan, N. Wang, C.S. Lee,
S.T. Lee, Adv. Mater. 13 (2001) 317.
[8] J.C. Boyer, F. Vetrone, J.A. Capobianco, A. Speghini, M.
Bettinelli, J. Appl. Phys. 93 (2003) 9460.
[9] H. Afifi, S. Marzouk, Mater. Chem. Phys. 80 (2003) 517.
[26] H.Y. Peng, X.T. Zhou, N. Wang, Y.F. Zheng, L.S. Liao, W.S.
Shi, C.S. Lee, S.T. Lee, J. Appl. Phys. 89 (2001) 727.