Size-tunable synthesis of SiO2 nanotubes via a simple in situ templatelike process

Article abstract of DOI:10.1021/jp064537w

SiO₂ nanotubes with tunable diameters and lengths have been successfully synthesized via a simple in situ templatelike process by thermal evaporation of SiO, ZnS, and GaN in a vertical induction furnace. The structure and morphologies were systematically investigated using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray spectrometry. Studies found that both the diameters and lengths of the SiO₂ nanotubes can be effectively tuned by simply changing the reaction temperatures. The range of changes was from 30 nm (diameter) and several hundred micrometers (length) at 1450°C to 100 nm (diameter) and 2-10 micrometers (length) at 1300°C. Varying some other experimental parameters results in the formation of additional SiO ₂-based nanostructures, such as core-shell ZnS-SiO₂ nanocables, ZnS nanoparticle filled SiO₂ nanotubes, and fluffy SiO₂ spheres. Based on the observations, an in situ templatelike process was proposed to explain the possible growth mechanism.

Full text of DOI:10.1021/jp064537w

23170
J. Phys. Chem. B 2006, 110, 23170-23174
Size-Tunable Synthesis of SiO2 Nanotubes via a Simple In Situ Templatelike Process
Guozhen Shen,* Yoshio Bando, and Dmitri Golberg
Nanoscale Materials Center, National Institute for Materials Science (NIMS), Namiki 1-1, Tsukuba,
Ibaraki 305-0044, Japan
ReceiVed: July 18, 2006; In Final Form: September 13, 2006
2
SiO nanotubes with tunable diameters and lengths have been successfully synthesized via a simple in situ
templatelike process by thermal evaporation of SiO, ZnS, and GaN in a vertical induction furnace. The structure
and morphologies were systematically investigated using X-ray diffraction, scanning electron microscopy,
transmission electron microscopy, and energy-dispersive X-ray spectrometry. Studies found that both the
diameters and lengths of the SiO
temperatures. The range of changes was from 30 nm (diameter) and several hundred micrometers (length) at
450 °C to 100 nm (diameter) and 2-10 micrometers (length) at 1300 °C. Varying some other experimental
2
nanotubes can be effectively tuned by simply changing the reaction
1
parameters results in the formation of additional SiO
2
-based nanostructures, such as core-shell ZnS-SiO
2
nanocables, ZnS nanoparticle filled SiO nanotubes, and fluffy SiO
2
2
spheres. Based on the observations, an
in situ templatelike process was proposed to explain the possible growth mechanism.
Introduction
1
Following the discovery of carbon nanotubes, one-dimen-
sional (1-D) inorganic nanotubes have become symbols of the
new and fast developing research area of nanotechnology due
to many significant potential applications.2 Numerous methods
have been developed to synthesize nanotubes with the layered
-7
2-20
or pseudo-layered structures as well as nonlayered nanotubes.
The prepared nanotubes include boron nitride, metal dichalco-
genides, metal dihalides, metal oxides and hydroxides, metal
borates, metals, silicon, metal nitrides, and metal phosphides,
etc.
Among various nanotubes, silica nanotubes (SiO2 nanotubes)
have received significant attention due to their room-temperature
light-emission characteristics in the visible range, a possible
usage for hosting materials in bioanalysis and bioseparation and
potential applications in optoelectronic nanodevices. Since
Harada and Adachi reported the synthesis of silica nanotubes
in 2000 by a surfactant-mediated method, several techniques
2
1-25
have been developed to prepare silica nanotubes.
For
Figure 1. SEM image of the obtained SiO
of ∼30 nm synthesized at 1450 °C.
2
nanotubes with diameters
example, Jang21 et al. reported the synthesis of size-tunable silica
nanotubes using a reverse microemulsion-mediated sol-gel
method. Nesper synthesized silica nanotubes with a high aspect
ratio using fibers of vanadium oxide hydrate as the templates.
Mayer used a templated surface sol-gel technique to get silica
nanotubes. Wang synthesized silica nanotubes using zinc oxide
nanowires as the removable templates. Our groups reported the
synthesis of ultralong silica nanotubes using an indium-assisted
vapor phase process.
In this work, we reported the synthesis of size-tunable silica
nanotubes via a simple in situ templatelike process by thermal
evaporation of a mixture of SiO, ZnS and GaN in a vertical
induction furnace. In this process, both the diameters and lengths
of the silica nanotubes can be easily tuned by changing the
reaction temperatures.
of a fused-quartz tube and an induction-heated cylinder made
of high purity graphite coated with a carbon fiber thermo-
insulating layer. The furnace has an inlet on its top and one
outlet on its base, respectively. A graphite crucible, containing
a mixture of ZnS (0.1 g), SiO (1 g), and GaN (0.1 g) powders,
was placed at the center cylinder zone. After evacuation of the
quartz tube to ∼100 Pa, pure Ar was introduced into the furnace
through the inlet at the base, which was maintained at a flow
rate of 200 sccm. The furnace was rapidly heated and kept at
1450 °C or 1300 °C for about 1 h. After the reaction was
terminated and the furnace cooled to room temperature, the
collected products were characterized using powder X-ray
diffraction (XRD, RINT 2200) with Cu KR radiation, scanning
electron microscopy (SEM, JSM-6700), and transmission elec-
tron microscopy (TEM, JEM-3000F) equipped with an energy-
dispersive X-ray spectrometer (EDS).
Experimental Section
SiO2 nanotubes were synthesized in a vertical induction
furnace as described in detail in the literature,26 which consists
1
0.1021/jp064537w CCC: $33.50 © 2006 American Chemical Society
Published on Web 10/24/2006

Size-Tunable Synthesis of SiO2 Nanotubes
J. Phys. Chem. B, Vol. 110, No. 46, 2006 23171
XRD. The XRD spectrum shows a broad peak at 2θ ) 20-
3
0°, indicating only amorphous materials within the product.
EDS studies reveal the composition of Si:O ) 1:2, thus the
formation of amorphous SiO2 (see below) is documented.
SiO2 Nanotubes with a Diameter of ∼30 nm Synthesized
at 1450 °C. Figure 1 shows the SEM image of the product
obtained at 1450 °C. It displays the formation of large scale
1-D wire-like nanostructures with lengths up to several hundred
micrometers. Increasing the magnification reveals that they are
SiO2 nanotubes with uniform diameters of about 30 nm (inset
in Figure 1).
The SiO2 nanotubes were further characterized using TEM.
Figures 2a and 2b are the TEM images of the synthesized SiO2
nanotubes. Typical nanotubes have smooth surfaces, round cross
sections for both their interiors and exteriors, and diameters of
about 30 nm in accordance to the SEM results. From these
images, we can also see that the SiO2 nanotubes have a very
thin wall thickness of about 5 nm. All the SiO2 nanotubes have
one round closed end and one open end as shown in Figures 2c
and 2d. The corresponding selected area electron diffraction
(SAED) pattern is shown in Figure 2b inset. The halolike SAED
pattern shows that the synthesized SiO2 nanotubes are in the
amorphous states. Figure 2e shows the HRTEM image of a
single SiO2 nanotube. No lattice fringe could be observed for
the nanotube also indicates its amorphous state. Figure 2f is a
typical EDX spectrum taken from the SiO2 nanotube. Only Si
and O peaks are present in the spectrum with the atomic ratio
of ∼0.5, confirming these nanotubes are amorphous SiO2
nanotubes. The peak at about 8 keV comes from the copper
foils used for TEM analysis.
SiO2 Nanotubes with Diameter of ∼100 nm Synthesized
at 1300 °C. During our experiments, it was found that the
diameters of the obtained SiO2 nanotubes can be easily tuned
by changing the reaction temperatures. Figures 3a and 3b show
the SEM images of the product obtained at 1300 °C, which
Figure 2. (a) TEM image of several SiO
2
nanotubes with typical
nanotube. (c,
diameters of ∼30 nm. (b) TEM image of a single SiO
2
d) TEM images of the closed and open tips of the synthesized SiO
nanotubes. (e) HRTEM image and (f) EDS spectrum of a SiO
nanotube.
2
2
Results and Discussion
Structure and Composition. After reaction, the powder was
collected from the inner wall of the crucible and checked using
Figure 3. (a, b) SEM images of the synthesized SiO
2
nanotubes with diameters of ∼100 nm synthesized at 1300 °C. (c) TEM image of the
obtained SiO
nanotube.
2
nanotubes. (d) TEM image of the SiO
2
nanotubes after acid treatment. (e, f) TEM images of the closed tip and open tip of a SiO
2

23172 J. Phys. Chem. B, Vol. 110, No. 46, 2006
Shen et al.
Figure 5. SEM images of the SiO
use of ZnS, which are composed of highly aligned SiO nanowires.
2
2
microrods obtained without the
Figure 4. (a) SEM image and (b) TEM image of the synthesized
coaxial ZnS/SiO nanocables. (c) SAED pattern of the nanocable in
part b. (d) EDS pattern taken from the inner nanowire. (e) SEM image
and (f) TEM image of SiO nanotubes partially filled with ZnS.
2
2
also indicates the formation of large-scale 1-D nanotube
structures at this temperature. However, high-magnification
SEM images show that the diameters and lengths of these
structures at 1300 °C change dramatically compared with those
obtained at 1450 °C.
Figure 3c is the TEM image of the products obtained at 1300
°
C. It indicates the formation of hollow SiO2 nanotubes with
outer diameters of ∼100 nm. The wall thickness of these
nanotubes can be derived from the high-magnifcation TEM
images in Figure 3d. It shows the wall thickness in the range
of 15-30 nm. Similar to those SiO2 nanotubes obtained at 1450
°
C, SiO2 nanotubes synthesized at 1300 °C also have one closed
tip and one open tip, which are demonstrated in Figures 3e and
f. The SAED pattern inset in Figure 3f also shows the
3
amorphous states of these nanotubes. Besides the straight SiO2
nanotubes, some interesting tubular SiO2 nanostructures, such
as “H”-type and “Y”-type, were also obtained under the present
experimental conditions (Supporting Information).
Effect of ZnS Concentration. All the above discussions have
confirmed that the present method is an efficient process to
produce size-tunable SiO2 nanotubes on a large scale. It was
also found that the final products are quite sensitive to the
concentration of ZnS in the source materials. Figure 4a shows
the SEM image of the product when 0.35 g of ZnS powder
was used. From this image, it can be clearly seen that 1-D
nanowires are obtained on a large scale. The corresponding TEM
image in Figure 4b showing clear contrast variations between
the outer part and inner part, indicates that these 1-D nanowires
are novel core-sheath heterostructures. The inner ZnS nanowires
have diameters of 50-100 nm and the thickness of the outer
SiO2 ranging from about 5 nm to 70 nm. Figure 4c shows the
SAED pattern taken from the core of the core-shell structure
shown in Figure 4b. The pattern can be indexed to wurtzite
ZnS along the [100] zone axis, which has the growth direction
along the [0001] plane. The EDS spectrum of the core nanowire
generated by a nanobeam is shown in Figure 4d. It shows the
Figure 6. (a, b) SEM images with different magnifications of the fluffy
SiO spheres synthesized in the absence of GaN. (c) The corresponding
SAED pattern of the fluffy SiO sphere.
2
2
peaks of Zn and S elements with a Zn/S molar ratio close to
the ZnS stoichiometry, indicating that the inner nanowire is ZnS.
Another kind of 1-D product was obtained when 0.2 g of
ZnS powder was used, and a typical SEM image is shown in
Figure 4e. It clearly shows the formation of partially ZnS-filled
SiO2 nanotubes. Typical partially ZnS-filled SiO2 nanotube has
a length of several micrometers and diameter of 100-350 nm.
Figure 4f is the TEM image of a single partially ZnS-filled SiO2
nanotube with diameter of about 300 nm which confirms the

Size-Tunable Synthesis of SiO2 Nanotubes
J. Phys. Chem. B, Vol. 110, No. 46, 2006 23173
Figure 7. Schematic illustration of the formation of SiO
2
nanotubes via an in situ templatelike process. (I) Formation of liquid-Ga droplets. (II)
Condensation of ZnS on Ga droplets. (III) Simultaneous growth of ZnS nanowires. (IV) Deposition of SiO
Formation of coaxial ZnS/SiO hetero-nanowires. (VI) Formation of SiO nanotubes.
2
on the surface of ZnS nanowires. (V)
2
2
TABLE 1: Relationships of the Products and the Source Materials and Reaction Temperatures
material T (°C) product
1300 micro-rods composed of aligned SiO
GaN + SiO
SiO
SiO
SiO
2
2
2
2
nanowires
GaN + SiO + ZnS (SiO:ZnS ) 10:1)
1450
300
Nanotubes (D: 30 nm, L: several hundred micrometers)
Nanotubes (D: 100 nm, L: several to tens micrometers)
1
GaN + SiO + ZnS (SiO:ZnS ) 5:1)
GaN + SiO + ZnS (SiO:ZnS ) 20:7)
GaN + SiO + ZnS (SiO:ZnS < 2:1)
SiO + ZnS
1300
partially ZnS filled SiO
coaxial ZnS/SiO nanocables
hierarchical ZnS/SiO nanowire heterostructures
fluffy SiO spheres
2
nanotubes
2
1300-13 50
1300
2
2
SEM results (see also Supporting Information). When increased
amounts of ZnS are used in the experiments, hierarchical ZnS/
SiO2 nanowire heterostructures are obtained instead of 1-D
nanowires according to our previous report.2
In the experiments, when the amount of ZnS was decreased
to lower than 0.1 g or when no ZnS was used, only Ga-attached
SiO2 microrods are obtained as shown in Figure 5a. Higher
magnification SEM images shown in Figures 5b and 5c depict
that the as-obtained SiO2 microrods are composed of highly
aligned amorphous SiO2 nanowires with very high density
rated, ZnS segregates and gives rise to the 1-D growth of ZnS
nanowires (III). With the increase of processing temperature,
thermal decomposition of the SiO powder results in the
formation of Si vapors which are easily oxidized by the residual
O2, or the unavoidable negligible leakage of O2 into the reaction
system, to SiO2, which is transported by the Ar gas and deposits
on the surface of newly formed ZnS nanowires (IV), resulting
in ZnS/SiO2 hetero-nanowires (V). Due to the high temperature,
the inner ZnS nanowires are evaporated, and finally hollow SiO2
nanotubes are formed (VI).
7
(
Supporting Information). Similar phenomena were also ob-
28
served by Yang et al.
Conclusion
Growth Mechanism. During the synthetic process, GaN
plays an important role in the thermal evaporation of SiO and
ZnS to generate SiO2 nanotubes. Without the use of GaN and
when all the other experimental parameters are kept constant,
only fluffy SiO2 spheres are obtained. Figures 6a and 6b show
the SEM images of the product obtained by thermal evaporation
of only ZnS and SiO at 1300 °C. They reveal the formation of
many fluffy spheres typically ranging from 1 to 10 µm in
diameter. Each fluffy sphere consists of numerous nanowires
of several tens to one hundred nanometers in diameter. The
formation of fluffy spheres was further confirmed using TEM
analysis (Supporting Information). It shows the arrangement of
nanowires into spherical structure as the SEM result. The
corresponding SAED pattern shown in Figure 6c confirms its
amorphous state, and EDS analysis reveals that these fluffy
spheres are pure SiO2 product. Table 1 shows the effect of
experiments on the final products, illustrating the relationships
of the products, source mateials, and reaction temperatures.
Based on the above analyses, an in situ templatelike process
was proposed to explain the formation of SiO2 nanotubes, and
the whole process can be schematically illustrated in Figure 7.
At high reaction temperature, GaN decomposes to Ga and the
newly formed Ga may be in the form of small-sized liquid
clusters (the decomposition of GaN at high temperature is
confirmed by the observation of many metallic Ga spheres
remained in the crucible after reaction). The Ga clusters are
then transported by Ar gas to the low temperature region, where
they deposit in the form of liquid droplets on the inner wall of
the graphite crucible (I). The as-formed Ga droplets are
energetically favored sites for the absorption of incoming ZnS
vapors generated in the system (II). Once becoming supersatu-
In conclusion, we developed a simple thermal evaporation
process for the synthesis of SiO2 nanotubes using in situ-formed
ZnS nanowires as the templates. Both the diameters and lengths
of the SiO2 nanotubes can be effectively tuned through only
changing the evaporation temperature. Careful investigations
of the experimental parameter influence on the final product
morphologies revealed that coaxial ZnS/SiO2 hetero-nanowires,
partially filled SiO2 nanotubes, and fluffy SiO2 spheres may
also form. The results suggest that the present method is not
only an efficient approach to fabricate pure SiO2 nanotubes with
tunable sizes but also a smart way to protect ZnS nanowires
from oxidation using SiO2 surface coatings and/or to fabricate
complex SiO2-based structures on a large scale.
Acknowledgment. We thank Y. Uemura for advice during
material synthesis and K. Kurashima for technical assistance
in TEM work.
Supporting Information Available: TEM images of H-type
and Y-type SiO2 nanotubes, EDS spectrum taken from the
partially ZnS-filled SiO2 nanotube, SEM images showing the
attached Ga catalyst, high-magnification SEM image of highly
aligned SiO2 nanowires, and SEM images and SAED pattern
of fluffy SiO2 spheres. This material is available free of charge
via the Internet at http://pubs.acs.org.
References and Notes
(1) Iijima, S. Nature (London) 1991, 354, 56.
(2) Dai, H. J.; Wang, E. W.; Lu, Y. Z.; Fan, S. S.; Lieber, C. M. Nature
(London) 1995, 375, 769.

23174 J. Phys. Chem. B, Vol. 110, No. 46, 2006
Shen et al.
(
3) (a) Chopra, N. G.; Luyken, R. J.; Cherrey, K.; Crespi, V. H.; Cohen,
(16) (a) Li, Y. B.; Bando, Y.; Golberg, AdV. Mater. 2003, 15, 1294. (b)
Tang, C. C.; Bando, Y.; Sato, T.; Kurashima, K. Chem. Commun. 2002,
1290. (c) Ma, R. Z.; Bando, Y.; Sato, T.; Kurashima, Chem. Mater. 2001,
13, 2965.
M. L.; Luoise, S. G.; Zittl, A. Science 1995, 269, 966. (b) Tenne, R.;
Margulis, L.; Genut, M.; Hodes, G. Nature 1992, 360, 444.
(4) (a) Hacohen, Y. R.; Grunbaum, E.; Tenne, R.; Sloan, J.; Hutchson,
J. L. Nature (London) 1998, 395, 336. (b) Spahr, M. E.; Bitterli, P.; Nesper,
R.; M u¨ ller, M.; Krumeich, F.; Nissen, U. Angew. Chem., Int. Ed. 1998, 37,
(17) (a) Wang, Y.; Lee, J. Y.; Zeng, H. C. Chem. Mater. 2005, 17, 3899.
(b) Li, X. X.; Cheng, F. Y.; Guo, B.; Chen, J. J. Phys. Chem. B 2005, 109,
14017.
7, 1263. (c) Feldman, Y.; Wasserman, E.; Srolovitz, D. J.; Tenne, R. Science
1
995, 267, 222.
(18) (a) Jia, C. J.; Sun, L. D.; Yan, Z. G.; You, L. P. Han, X. D.; Pang,
Y. C.; Zhang, Z.; Yan, C. H. Angew. Chem., Int. Ed. 2005, 44, 4328. (b)
Sehayek, T.; Lahav, M.; Popovitz-Biro, R.; Vaskevich, A.; Rubinstein, I.
Chem. Mater. 2005, 17, 3743. (c) Liu, Z. Q.; Zhang, D. H.; Han, S.; Li, C.;
Lei, B.; Lu, W. G.; Fang, J. Y.; Zhou, C. W. J. Am. Chem. Soc. 2005, 127,
6.
(19) (a) Park, T. J.; Mao, Y. B.; Wong, S. S. Chem. Commun. 2004,
2708. (b) Wang, J. X.; Wen, L. X.; Wang, Z. H.; Wang, M.; Shao, L.;
Chen, J. F. Script. Mater. 2004, 51, 1035. (c) Qu, L. T.; Shi, G. Q.; Wu, X.
F.; Fan, B. AdV. Mater. 2004, 16, 1200.
(20) (a) Guo, L.; Liu, C. M.; Wang, R. M.; Xu, H. B.; Wu, Z. Y.; Yang,
S. J. Am. Chem. Soc. 2004, 126, 4530. (b) Wang, X.; Zhuang, J.; Chen, J.;
Zhou, K. B.; Li, Y. D. Angew. Chem., Int. Ed. 2004, 43, 2017.
(21) (a) Harada, M.; Adachi, M. AdV. Mater. 2000, 12, 839. (b) Jang, J.
S.; Yoo, H. S. AdV. Mater. 2004, 16, 799. (c) Wang, L. Z.; Tomura, S.;
Ohashi, F.; Maeda, M.; Suzuki, M.; Inukai, K. J. Mater. Chem. 2001, 11,
1465.
(22) (a) Zygmunt, J.; Krumeich, F.; Nesper, R. AdV. Mater. 2003, 15,
1538. (b) Li, Y. B.; Bando, Y.; Golberg, D. AdV. Mater. 2004, 16, 37.
(23) (a) Chen, Y. J.; Xue, X. Y.; Wang, T. H. Nanotechnology 2005,
16, 1978. (b) Wang, Z. L.; Gao, R. P.; Gole, J. L.; Stout, J. D. AdV. Mater.
2000, 12, 1938.
(5) (a) Nath, M.; Rao, C. N. R. J. Am. Chem. Soc. 2001, 123, 4841.
(
1
b) Ajayan, P. M.; Stephan, O.; Redlich, P.; Colliex, C. Nature (London)
995, 375, 564.
(6) (a) Hutleen, J. C.; Jirage, K. B.; Martin, C. R. J. Am. Chem. Soc.
1
998, 120, 6603. (b) Mayers, B.; Xia, Y. N. AdV. Mater. 2002, 14, 279. (c)
Nakamura, H.; Matsui, Y. J. Am. Chem. Soc. 1995, 117, 2651.
(7) (a) Xu, A. W.; Fang, Y. P.; You, L. P.; Liu, H. Q. J. Am. Chem.
Soc. 2003, 125, 1494. (b) Li, Y.; Wang, J.; Deng, Z.; Wu, Y.; Sun, X.; Yu,
D.; Yang, P. D. J. Am. Chem. Soc. 2001, 123, 9904. (c) Shen, G. Z.; Bando,
Y.; Zhi, C. Y.; Golberg, D. J. Phys. Chem. B 2006, 110, 10714.
(8) (a) Ma, R. Z.; Bando, Y.; Golberg, D.; Sato, T. Angew. Chem.,
Int. Ed. 2003, 42, 1836. (b) Hu, J. Q.; Bando, Y.; Liu, Z. W.; Zhan, J. H.;
Golberg, D.; Sekiguchi, T. Angew. Chem., Int. Ed. 2004, 43, 63.
(9) (a) Goldberger, J.; He, R. R.; Zhang, Y. F.; Lee, S.; Yan, H. Q.;
Choi, H. J.; Yang, P. D. Science 2003, 422, 599. (b) Yang, P. D. Abstr.
Pap. Am. Chem. Soc. 2004, 227, U248. (c) Remskar, M. AdV. Mater. 2004,
1
6, 1407.
(
10) (a) Li, Y. B.; Bando, Y.; Golberg, D. AdV. Mater. 2005, 17, 1401.
b) Yin, L. W.; Bando, Y.; Zhu, Y. C.; Li, M. S.; Tang, C. C.; Golberg, D.
AdV. Mater. 2005, 17, 213.
11) (a) Tang, C. C.; Bando, Y.; Golberg, D.; Ma, R. Z. Angew. Chem.,
(
(
Int. Ed. 2005, 44, 576. (b) Yin, L. W.; Bando, Y.; Golberg, D.; Li, M. S.
AdV. Mater. 2004, 16, 1833. (c) Yin, L. W.; Bando, Y.; Golberg, D.; Li,
M. S. Appl. Phys. Lett. 2004, 85, 3869.
(24) (a) Zhang, M.; Ciocan, E.; Bando, Y.; Wada, K.; Cheng, L. L.;
Pirouz, P. Appl. Phys. Lett. 2002, 80, 491. (b) Yin, Y. D.; Lu, Y.; Sun, Y.
G.; Xia, Y. N. Nano Lett. 2002, 2, 427. (c) Fan, R.; Wu, Y.; Li, D.; Yue,
M.; Majumdar, A.; Yang, P. D. J. Am. Chem. Soc. 2003, 125, 5254.
(25) (a) Hu, J. Q.; Meng, X. M.; Jiang, Y.; Lee, C. S.; Lee, S. T. AdV.
Mater. 2003, 15, 70. (b) Yao, B. D.; Fleming, D.; Morris, M. A.; Lawrence,
S. E. Chem. Mater. 2004, 16, 4851.
(26) (a) Shen, G. Z.; Bando, Y.; Liu, B. D.; Tang, C. C.; Huang, Q.;
Golberg, D. Chem.sEur. J. 2006, 12, 2987. (b) Han, W.; Bando, Y.;
Kurashima, K.; Sato, Y. Appl. Phys. Lett. 1998, 73, 3085.
(27) Shen, G. Z.; Bando, Y.; Tang, C. C.; Golberg, D. J. Phys. Chem.
B 2006, 110, 7199.
(12) (a) Yu, S. F.; Welp, U.; Hua, L. Z.; Rydh, A.; Kwok, W. K.; Wang,
H. H. Chem. Mater. 2005, 17, 3445. (b) Yang, J.; Liu, Y. C.; Lin, H. M.;
Chen, C. C. AdV. Mater. 2004, 16, 713.
(
13) (a) Yin, L. W.; Bando, Y.; Zhu, Y. C.; Golberg, D.; Li, M. S. AdV.
Mater. 2004, 16, 929. (b) Yin, L. W.; Bando, Y.; Zhu, Y. C.; Golberg, D.;
Li, M. S. Appl. Phys. Lett. 2004, 84, 3912.
(
14) Zhan, J. H.; Bando, Y.; Hu, J. Q.; Golberg, D. Inorg. Chem. 2004,
3, 2462.
15) (a) Li, Y. B.; Bando, Y.; Golberg, D.; Uemura, Y. Appl. Phys.
4
(
Lett. 2003, 83, 3999. (b) Hu, J. Q.; Bando, Y.; Golberg, D.; Liu, Q. L.
Angew. Chem., Int. Ed. 2003, 42, 3493.
(28) Zheng, B.; Wu, Y. Y.; Yang, P. D.; Liu, J. AdV. Mater. 2001, 14,
122.