Aqueous mineralization process to synthesize uniform shuttle-like BaMoO4 microcrystals at room temperature

Article abstract of DOI:10.1016/j.jssc.2007.07.010

Single-crystalline BaMoO₄ microcrystals with uniform shuttle-like morphology have been successfully prepared via a facile aqueous solution mineralization process at room temperature. It was found that the pH value and the reaction temperature had important influences on the formation of the BaMoO₄ microcrystals. The shuttle-like microcrystals can be obtained in alkaline aqueous solution (pH=9-14), and when the pH value was adjusted to 6-7, cocoon-like microcrystals appeared. A possible two-stage growth process has been proposed, and the Ostwald ripening was responsible for the formation of the shuttle-like BaMoO₄ microcrystals. The products were characterized by XRD, XPS, FESEM, HRTEM and Raman spectroscopy. Room-temperature photoluminescence indicated that the as-prepared BaMoO₄ microcrystals had a strong blue emission peak centered at 438 nm.

Full text of DOI:10.1016/j.jssc.2007.07.010

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Journal of Solid State Chemistry 180 (2007) 3288–3295
www.elsevier.com/locate/jssc
Aqueous mineralization process to synthesize uniform shuttle-like
BaMoO microcrystals at room temperature
4
Xueying Wu, Jin Du, Haibo Li, Maofeng Zhang, Baojuan Xi,
Ã
Hai Fan, Yongchun Zhu, Yitai Qian
Hefei National Laboratory for Physical Sciences at Microscale, Department of Chemistry, University of Science and Technology of China,
Number 96, JinZhai Road, Hefei City, Anhui Province 230026, People’s Republic of China
Received 24 May 2007; received in revised form 17 July 2007; accepted 18 July 2007
Available online 26 July 2007
Abstract
Single-crystalline BaMoO
solution mineralization process at room temperature. It was found that the pH value and the reaction temperature had important
influences on the formation of the BaMoO microcrystals. The shuttle-like microcrystals can be obtained in alkaline aqueous solution
pH ¼ 9–14), and when the pH value was adjusted to 6–7, cocoon-like microcrystals appeared. A possible two-stage growth process
has been proposed, and the Ostwald ripening was responsible for the formation of the shuttle-like BaMoO microcrystals. The products
4
microcrystals with uniform shuttle-like morphology have been successfully prepared via a facile aqueous
4
(
4
were characterized by XRD, XPS, FESEM, HRTEM and Raman spectroscopy. Room-temperature photoluminescence indicated that
the as-prepared BaMoO microcrystals had a strong blue emission peak centered at 438 nm.
r 2007 Published by Elsevier Inc.
4
Keywords: Crystal morphology; Mineralization process; Microcrystal; Molybdates
1
. Introduction
among the metal molybdate families, which has potential
applications in various fields, such as photoluminescence
(PL) and hosts for lanthanide-actived lasers [5]. Tradition-
ally, various methods including templated synthesis [6],
complex polymerization method [7], Langmuir–Blodgett
technology [8], chemical vapor deposition [9], and electro-
chemical method [10] were applied to synthesize BaMoO4
with different shapes, such as nanopowders [7], microfilms
[10]. Recently, the techniques using microemulsions and
reverse micelles have been used to prepare nano- or
microscaled BaMoO4 crystals. For example, dendritic
Molybdates of relatively large bivalent cations (ionic
˚
radius 40.99 A: Ca, Ba, Pb, Sr) usually exit in the so-called
scheelite structure form (scheelite ¼ CaWO ), where the
4
molybdenum atom adopts a tetrahedral coordination [1].
Scheelite-type molybdates are reciprocally soluble over the
entire compositional range [2], which results in a rich
family of solid-state solution compounds. Molybdates of
˚
smaller bivalent cations MMoO (ionic radius o0.77 A:
4
M ¼ Fe, Mn, Co, Ni, Mg, Zn), however, belong to the
wolframite structure (wolframite ¼ {(Fe, Mn) WO },
BaMoO microcrystals have been prepared by a micro-
4
4
where the molybdenum atom adopts an overall 6-fold
coordination [3].
As to the BaMoO , which has two structures, namely
emulsion-mediated method at room temperature [11] and
BaMoO nanobelt superstructures were synthesized at a
4
catanionic reverse-micelle system at 50 1C [12].
4
cubic (a) and tetragonal distorted scheelite (b), depends on
In recent years, a room-temperature aqueous miner-
alization process has been developed, which required
mild reaction conditions under normal atmospheric pres-
sure, ideally, mimicking the natural mineralogical or
biological process conditions [13]. In the mineralization
process, especially the technique using polymer or double
the applied temperature [4]. BaMoO with the scheelite
structure is one of the most important inorganic materials
4
Ã
Corresponding author. Fax: +86 551 3607402.
E-mail address: ytqian@ustc.edu.cn (Y. Qian).
0022-4596/$ - see front matter r 2007 Published by Elsevier Inc.
doi:10.1016/j.jssc.2007.07.010

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hydrophilic block copolymers (DHBCS) as crystal modi-
3. Results and discussions
fiers have enriched its application in the nanoscience, as it
not only generate novel superstructures but also control the
nucleation and growth process [14,15]. Until now, many
micro- or nanosized materials have been successfully
synthesized by this technique. For example, the complex
spherical BaCO3 superstructures have been synthesized
by a facile mineralization process with the poly (sodium
3.1. XRD pattern of the prepared products
Fig. 1 shows the X-ray diffraction (XRD) pattern of the
as-prepared product. All the peaks can be well indexed to
the tetragonal phase of BaMoO4 with calculated cell
˚
˚
constants a ¼ 5.569 A, c ¼ 12.794 A, which are in good
4
-styrenesulfonate) (PSS) and poly (allylamine hydrochlor-
agreement with the literature data (JCPDS card number
˚
˚
ide) (PAH) as structure-directing agents [16]. Funnel-like
BaCrO superstructures and BaSO fiber bundles have also
been prepared by polymer-controlled mineralization reac-
tions using the sodium polyacrylate as structure-directing
agents [17].
29-0193, a ¼ 5.580 A, c ¼ 12.820 A). No peaks of other
impurities were detected, which indicated that the products
had a high purity. In addition, the strong and sharp
diffraction peaks also suggested the high crystallization of
4
4
BaMoO products.
4
In this paper, we demonstrate a facile room-temperature
aqueous solution mineralization process to prepare the
uniform shuttle-like BaMoO microcrystals without any
3.2. Raman spectrum and XPS analysis
4
structure-directing agent. The influences of pH value and
the reaction temperature on the morphology of the as-
prepared products and the growth process of the BaMoO4
microstructures have been systematically investigated in
such a reaction system. It was found that the alkaline
aqueous solution (pH ¼ 9–14) and room temperature
BaMoO with the scheelite structure had characteristic
4
6
Raman peaks due to the C4h or I4 /a symmetry. The
1
Raman spectrum of the shuttle-like BaMoO microcrystals
4
is shown in Fig. 2a. It can be seen that there are six Raman
ꢁ
1
peaks at 325, 347, 360, 792, 837, and 891 cm , which
correspond to several different vibrational modes, includ-
ing n (B ), n (B ), n (E ), n (E ), n (B ), and n (A ), of the
(
25–35 1C) were the optimal condition for the formation
2
g
4
g
4
g
3
g
3
g
1
g
of the shuttle-like BaMoO microcrystals.
tetragonal BaMoO crystals [18]. Obviously, the Raman
4
4
spectrum also shows the well-resolved sharp peaks for the
BaMoO4 microcrystals, indicating that the synthesized
crystals are highly crystallized.
2
. Experiment section
All the chemicals (of analytical grade) are purchased
from Shanghai Chemical Regent Company, and used
without further purification.
The purity and the composition of the product were
further investigated by X-ray photoelectron spectroscopy
(XPS). The peak at about 780.05 eV is attributed to Ba 3d5/2
(Fig. 2b), and the peak at 231.65 eV is belonging to the Mo
3d5/2 (Fig. 2c), which are consistent with those observed in
In a typical procedure, 0.5 mmol BaCl ꢀ 2H O and
2
2
0
water, respectively. After the H MoO aqueous solution
.5 mmol H MoO were dissolved into 20 mL distilled
2 4
2
4
BaMoO [10]. As shown in Fig. 2d, the O1s core-level
4
was fixed to pH value of 9 using NaOH (1 M) aqueous
solution, the BaCl .aqueous solution was dripped to it
spectrum is broad, and three Gaussians are resolved by
using a curve-fitting procedure. The peak at the lower
2
2ꢁ
under stirring for about 5 min. The reaction system was
kept still and the resultant mixture was incubated for 6 h at
room temperature. After that, the as-obtained white
precipitate was filtered and washed with distilled
water and absolute ethanol several times to remove ions
possibly remnant in the final products and dried at 60 1C in
air for 6 h.
energy of 529.95 eV, is in agreement with that for O in
BaMoO [10], while peaks at the high energies of 531.95 and
4
1
12
The phase and purity of the products were examined by
X-ray powder diffractometer using an X’Per PRD SUPER
˚
with CuKa radiation (l ¼ 1.5418 A). The operation voltage
and current were kept at 40 kV and 40 mA, respectively.
The 2y range was 10–701 in steps of 0.021 with a count
time of 2 s. The field emission scanning election microscopy
200
2
04
3
12
1
16
(
FESEM) images were taken on a JEOLJSM-6700FSEM.
High-resolution TEM images were obtained using a JEOL
010 electron microscope (200 kV). The Raman spectrum
004
3
16
2
20
224
2
11
2
08
2
was obtained at room temperature with a LABRAM-HR
Laser Micro-Raman spectrometer. The room temperature
PL spectrum was performed on a Jobin Yvon-Labram
spectrometer using the 370 nm excition line of the He–Cd
laser.
10
20
30
40
θ/degree
50
60
70
2
Fig. 1. XRD pattern of the as-prepared product.

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3290
Ba3d5/2
8
91
3
25
7
92
8
37
3
47
3
60
200
400
600
800
1000
770 775 780 785 790 795 800 805
Binding energy/ eV
Wavenumber/cm-1
Mo3d5/2
O1s
2
22 224 226 228 230 232 234 236 238 240 242
524 526 528 530 532 534 536 538 540
Binding energy/ eV
Binding energy/ eV
Fig. 2. (a) Raman spectra and XPS analysis; (b) for Ba element; (c) for Mo element; (d) for O element.
5
33.2 eV, respectively, are attributed to oxygen absorbed
(SAED) pattern of the corresponding edge of the shuttle-
like BaMoO4 microcrystals, which was obtained by
¯
focusing the election beam along the [151] axis. There a
highly symmetrical dotted lattice can be seen, which reveals
the single crystalline nature of the product (more ED
patterns are provided in Fig. S1). Both the HRTEM image
and the SAED pattern demonstrate that the shuttle-like
onto the surface of the products. Thus, the XPS results
reveal the presence of Ba, Mo and O elements in the
products, and confirm that the valence of Ba, Mo and O
elements are +2, +6 and ꢁ2 respectively.
3
.3. Morphology of the products
BaMoO microcrystals have a preferential growth orienta-
4
The morphology and dimension of the as-prepared
products for 6 h (pH ¼ 9) were examined by FESEM.
tion along the c-axis direction.
Fig. 3a shows the panorama of the BaMoO microcrystals,
4
3.4. The reaction conditions on the formation of shuttle-like
BaMoO microcrystals
which consists of a large quantity of relatively uniform
shuttle-like crystals with two sharp tips and four symme-
trically grown protrusions in the middle, which has a
typical 4-fold symmetry. It is interesting to find that they
also have deep grooves between the two neighboring
4
3.4.1. The influence of pH
It was found that the pH had an important role in the
crystallization and shape control of BaMoO . And the
4
surfaces. A single shuttle-like BaMoO crystal is 40–60 mm
alkaline aqueous solution (pH ¼ 9–14) was the optimal
4
in length and 5–10 mm in width for the middle section,
respectively. A HRTEM image in Fig. 3c was taken from
the selected area marked in Fig. 3b, showing lattice spacing
of ca. 0.513 nm, which agrees well with the separation
between the {1 0 1} lattice planes of tetragonal BaMoO4.
The inset in Fig. 3c is selected area election diffraction
condition for the formation of the shuttle-like BaMoO
4
microcrystals. If the pH value was lower than 6, no product
can be obtained because the precipitate could dissolve in
such an acidic solution When the pH of mixed aqueous
solution was adjusted to 6–7, cocoon-like microcrystals
with a diameter of about 500–600 nm and a length of

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3291
Fig. 3. (a) FESEM image of the products showing that the product contains a large quantity of shuttle-like microcrystals; (b) TEM image of a single
shuttle-like BaMoO microcrystal; (c) HRTEM image of the rim part of the microcrystal with clearly resolved lattice fringes. The inset in Fig. 3c is the
SAED pattern recorded from the same microcrystal.
4
4
–5 mm can be seen. (It has good crystallinity and the XRD
affected by external conditions such as temperature,
supersaturation and so on. When the temperature is quite
low, the crystal growth habit is mainly affected by the
interior structure, while the temperature increases, the
growth rates of different faces for the shuttle-like particles
arise and the preferential growth eliminates, thus form the
cube-like particles. The above results suggest that further
increasing of reaction temperature does not favor the
formation of shuttle-like microcrystals and the room
temperature (25–35 1C) might be the optimal condition
pattern is shown in Fig. S2.) The SEM and TEM images
for the product are shown in Fig. 4a and b, from which we
can clearly see that the surface structure of the BaMoO4
product is composed of irregular subunits, and the subunits
assemble into such architecture.
3
.4.2. The influence of reaction temperature
In addition, the reaction temperature also plays a key
role in the formation of shuttle-like BaMoO microcrystals.
4
Fig. 5 shows the TEM images of products synthesized at
room temperature, 50, 80 and 120 1C. And Fig. 5a is the
TEM image of the product obtained at room temperature,
which is consistent with the SEM image in Fig. 3a. When
the reaction temperature was set at 50 1C, the morphology
of the products has no obvious change with that obtained
at room temperature, except that the size becomes smaller
for the formation of shuttle-like BaMoO microcrystals.
4
3.5. The growth process of the BaMoO microcrystals
4
To substantially understand the growth process of the
shuttle-like BaMoO microcrystals, we had systematically
4
surveyed the growth process by analyzing the samples at
different growth stages. Fig. 7a–e shows the FESEM
images for the samples taken at different stages of the aging
times. The detailed growth process of the products may be
described as follows: Fig. 7a was the SEM image of the
products that were formed after the two mixed solutions
were stirred for 10 min. The product mainly consisted of
different morphologies of BaMoO4 particles, such as
irregular particles and some imperfect bipyramidal-like
particles. It is interesting that the bipyramidal-like particles
have different nucleation rates between the top section and
the middle section. The top section perfectly grew, whereas
(
Fig. 5b). At 80 1C, many oval-like particles with a mean
length of 3 mm and a mean width of 1.5 mm were formed
Fig. 5c). And if increasing the reaction temperature to
20 1C, some cube-like particles were obtained, as shown in
(
1
Fig. 5d. That is to say, with the increasing of the reaction
temperature, the shuttle-like microcrystals gradually devel-
oped into particles, and this is different from the synthesis
of BaWO , which experienced a morphological transform
4
process from the shuttle-like particles to dendrites [19].
Generally, the growth habit of crystals is mainly deter-
mined by the internal structure of a given crystals and

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Fig. 4. FESEM images of the samples at PH ¼ 6–7: (a) low-magnification SEM image of the products showing that the product contains a large quantity
of cocoon-like materials; (b) the TEM image of the cocoon-like BaMoO microcrystals.
4
Fig. 5. The TEM images of the products at different reaction temperatures: (a) room temperature; (b) at 50 1C; (c) at 80 1C; (d) at 120 1C.
the middle section was composed of many irregular
particles and led to the presence of the many interstices.
When the aging time was extended to 30 min, the quantity
of the irregular particles decreased gradually and more
bipyramidal-like particles can be seen, but the middle
section was still not compact enough to combine well with
the top section, as observed from the inset of Fig. 7b. If the
aging time was prolonged to 1 h, the irregular particles
vanished and only the bipyramidal-like particles with a
length of about 10 mm could be found. Via close examina-
tion of the Fig. 7c, it is clear that four protrusions in the
middle section for the bipyramidal-like particles had come

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3293
into being and there were many holes in their faces, which
might indicate that the crystallization was poor. With
increasing the aging time to 3 h, there were no obvious
changes for the bipyramidal-like particles except that the
surfaces became smoother (shown in Fig. 7d). With the
extension of the mineralization process to 6 h, perfect
shuttle-like microcrystals with the deep grooves between
the neighboring surfaces and four symmetrically grown
protrusions in the middle were produced on a large scale.
From the above results, we can find that the ratio of the
length to the width of the products has become larger and
better crystallization with increasing the aging time. Fig. 6
shows the XRD patterns of the products obtained at
prolonged aging times, all of which can be indexed as the
c
tetragonal phase of BaMoO . Similar diffraction peaks can
4
be seen except that the intensity of the peaks increases.
In general, two classical crystal growth modes have been
often used to explain the growth process of inorganic
materials: one is the so-called Ostwald ripening [20], in
which the large particles grow at the cost of the small ones
through the diffusion of ions, atoms, or molecules within
an assemble of crystallites; another growth mode involving
mostly oriented particle aggregation [21–24], which were
termed conceptually as ‘‘the oriented attachment’’ by Penn
and Banfleld et al. [25–28], has emerged recently as
highlighted by Allvisatos [29]. And in the experiment, the
formation of cocoon-like microcrystals at pH 6–7 belongs
to the oriented attachment process. In this mechanism, the
b
a
10
20
30
40
50
60
70
2
θ/degree
Fig. 6. The XRD patterns obtained at different aging times: (a) 10 min;
b) 1 h; (c) 3 h.
(
Fig. 7. FESEM images of the samples with different aging time: (a) 10 min; (b) 30 min; (c) 1 h; (d) 3 h; (e) 6 h.

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X. Wu et al. / Journal of Solid State Chemistry 180 (2007) 3288–3295
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bigger particles grow from small primary particles through
an oriented attachment process, in which the adjacent
particles are self-assembled by sharing a common crystal-
lographic orientation and docking of these particles at a
planar interface.
formed with further growth of bipyramidal-like particles,
which is mainly a kinetically controlled process. In addition,
reduction of surface energy is the primary driving force for
the crystal growth and morphology evolution. From the
FESEM images, it was reasonable to presume that the
bipyramidal-like particles have two growth directions along
c- and a-axis. Meanwhile, just because of the nonequili-
brium growth rates of the two directions, the growth rates
of the former was larger than that of the latter, resulting in
the appearance of the deep grooves between the neighbor-
ing faces. Finally, shuttle-like microcrystals were obtained.
And the structure of shuttle-like microcrystals further
confirmed that the microcrystals had a preferential growth
orientation along the c-axis direction.
Based on the XRD and the FESEM measurements, we
proposed that the process for the formation of the shuttle-
like BaMoO microcrystals could be divided into two stages.
4
The first one is the formation of the perfect bipyramidal-like
particles, which belongs to a typical Ostwald ripening
2+
process. When Ba
2ꢁ
ions and MoO4 ions were mixed, a
highly supersaturated solution was formed, leading to the
coexistence of the irregular particles and the bipyramidal-like
BaMoO particles, as shown in Fig. 7a. It is clear that the
4
crystalline phase of the nuclei is critical for directing
the intrinsic shapes of the crystals due to its characteristic
symmetry and structure. As the aging time proceeded, the
bipyramidal-like particles became predominating in the
products via a transformation process using the irregular
particles as precursors. The formation process of the
bipyramidal-like particles is shown in Fig. 8 (Stage 1).
The second stage is the evolution process from the
bipyramidal-like particles to the shuttle-like microcrystals.
Fig. 8 (Stage 2) is the schematic illustration of the formation
3
.6. PL spectrum
The PL spectrum of the as-synthesized product was
investigated at room temperature. As shown in Fig. 9,
370nm
of the shuttle-like BaMoO microcrystals evolved from the
4
bipyramidal-like particles. The newly grown nuclei first
grew into bipyramidal-like particles, and then shuttle-like
BaMoO4 microcrystals with excellent symmetry were
240 260 280 300 320 340 360 380 400 420 440
Wavelength/nm
438nm
Fig. 8. Schematic illustration of the formation process of the shuttle-like
4
BaMoO microcrystals. Stage 1: the formation of the perfect bipyramidal-
like particles through the Ostwald ripening process (I) the coexistence of
the irregular particles and the bipyramidal-like particles (II) the quantity
of bipyramidal-like particles increased at the cost of the small particles
350
400
450
500
550
600
650
700
750
(III) the only presence of the bipyramidal-like particles and (IV) the
perfect bipyramidal-like particles. Stage 2: the evolution process from the
Wavelength/nm
bipyramidal-like particles to the obtained shuttle-like BaMoO
crystals.
4
micro-
Fig. 9. Room temperature photoluminescence spectra of the shuttle-like
BaMoO microcrystals: (a) excitation spectra; (b) emission spectra.
4

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3295
BaMoO microcrystals display a strong blue emission peak
4
[3] S.H. Yu, B. Liu, M.S. Mo, J.H. Huang, X.M. Liu, Y.T. Qian, Adv.
Funct. Mater. 13 (2003) 639.
in the range of 400–600 nm, centered around 438 nm when
excited at 370 nm, The spectral characteristic of BaMoO4
was also very similar to those of the other scheelite
[
4] T.T. Basiev, A.A. Sobol, Y.U.K. Voronko, P.G. Zverev, Opt. Mater.
5 (2000) 205.
1
[5] J.H. Ryu, J.W. Yoon, C.S. Lim, K.B. Shim, Mater. Res. Bull. 40
(2005) 1468.
molybdate crystals (MMoO , M ¼ Ca, Sr, Pb) [30]. The
4
emission band shape might be explained by considering the
Jahn-Teller active vibration modes of T symmetry that
[6] M. Wirtz, M. Parker, Y. Kobayashi, C.R. Martin, Chem. Eur. J. 8
2002) 3572.
(
2
2
ꢁ
[7] A.P.A. Marques, D.M.A. Melo, C.A. Paskocimas, P.S. Pizani,
M.R. Joya, E.R. Leite, E. Longo, J. Solid State Chem. 179 (2006)
influences the [MoO4] complex anion of slightly distorted
tetrahedral symmetry, leading to a structured absorption
6
73.
band for the A -T
transition [31–33]. The strong
1
1(2)
[8] F. Kim, S. Kwan, J. Akana, P.D. Yang, J. Am. Chem. Soc. 123
(2000) 4360.
luminescence intensity indicated the perfection of the
microstructure and good crystallization, since the optical
property of the BaMoO is comparable with that of the
previously reported BaMoO4 particles [7] that were
obtained by complex polymerization method.
[9] J.P. Ge, Y.D. Li, Adv. Funct. Mater. 14 (2004) 157.
[
[
[
[
10] J. Bi, D.Q. Xiao, D.J. Gao, P. Yu, G.L. Yu, W. Zhang, J.G. Zhu,
Cryst. Res. Technol. 38 (2003) 938.
4
11] Q. Gong, X.F. Qian, H.L. Cao, W.M. Du, X.D. Ma, M.S. Mo,
J. Phys. Chem. B 110 (2006) 19295.
12] H.T. Shi, L.M. Qi, J.M. Ma, N.Z. Wu, Adv. Funct. Mater. 15 (2005)
4
42.
4
. Conclusions
13] Y. Xia, P. Yang, Y. Sun, Y. Wu, B. Mayers, B. Gates, Y. Yin,
F. Kim, H. Yan, Adv. Mater. 15 (2003) 353.
In summary, shuttle-like BaMoO4 microcrystals were
[
[
14] H. Colfen, S. Mann, Angew. Chem. Int. Ed. 42 (2003) 2361.
15] S.H. Yu, H. Colfen, J. Mater. Chem. 14 (2004) 2124.
successfully prepared by a simple aqueous solution
mineralization process without the assistance of any
structure-directing agent at room temperature. The influ-
ences of pH value, the reaction temperature and the growth
process were examined in detail. In addition, the optical
properties of products had been examined by Raman
spectrum and PL spectrum. Furthermore, the feasibility
and ease of this synthesis route are worth exploring for
other inorganic systems, since it is an efficient and facile
solution-based method with promising advantages com-
pared with the traditional high-temperature approach.
[16] S.H. Yu, H. Colfen, A.W. Xu, W.F. Dong, Cryst. Growth Design 4
2004) 33.
17] S.H. Yu, M. Antonietti, H. Colfen, J. Hartmann, Nano Lett. 3 (2003)
79.
18] C.T. Xia, V.M. Fuenzalida, R.A. Zarate, J. Alloys Compd. 316
2001) 250.
[19] X.M. Wang, H.Y. Xu, H. Wang, H. Yan, J. Cryst. Growth 284
2005) 260.
(
[
[
3
(
(
[
[
20] T. Sugimoto, Adv. Colloid Interface Sci. 28 (1987) 65.
21] J.K. Bailey, C.J. Brinker, M.L. Mecartney, J. Colloid Interface Sci.
1
57 (1993) 1.
22] V. Privman, D.V. Goia, J. Park, E. Matijevic, J. Colloid Interface Sci.
13 (1999) 36.
[
2
[
[
23] A. Chemseddine, T. Moritz, Eur. J. Inorg. Chem. (1999) 235.
24] G.J. Zhou, M.K. Lu, F. Gu, D. Xu, D.R. Yuan, J. Cryst. Growth 276
Acknowledgments
(
2005) 577.
This work is financially supported by the National
Natural Science Foundation of China (No. 20431020) and
the 973 Project of China (No. 2005CB623601).
[
[
25] R.L. Penn, J.F. Baneld, Science 281 (1998) 969.
26] R.L. Penn, J.F. Baneld, Geochim. Cosmochim. Acta 63 (1999)
1549.
[
[
[
27] J.F. Baneld, S.A. Welch, H. Zhang, T.T. Ebert, R.L. Penn, Science
2
89 (2000) 751.
28] R.L. Penn, A.T. Stone, D.R. Veblen, J. Phys. Chem. B 105 (2001)
690.
29] A.P. Alivisatos, Science 289 (2000) 736.
Appendix A. Supporting Information
4
Supplementary data associated with this article can be
found in the online version at doi:10.1016/j.jssc.2007.07.010.
[30] M. Nikl, P. Bohacek, E. Mihokova, M. Kobayashi, M. Ishii, Y.
Usuki, V. Babin, A. Stolovich, S. Zazubovich, M. Bacci, J. Lumin. 87
(
2000) 1136.
[
[
[
31] Y. Toyozawa, M. Inoue, J. Phys. Soc. Jpn. 21 (1966) 1663.
32] Z.D. Lou, J.H. Hao, M. Cocivera, J. Lumin. 99 (2002) 349.
33] K. Polak, M. Nikl, K. Nitsch, M. Kobayashi, M. Ishii, Y. Usuki, O.
Jarolimek, J. Lumin. 72 (1997) 781.
References
[
[
1] B.G. Hyde, S. Andersson, Inorganic Crystal Structure, Wiley,
New York, 1989.
2] V.D. Zhuravlev, M.Y. Khodos, Y.A. Velikodnyi, Russ. J. Inorg.
Chem. 39 (1994) 464.