COL 10(11), 111603(2012) CHINESE OPTICS LETTERS November 10, 2012
Structure and photoluminescence properties of fishbone-like
PbMoO
4
nanostructures obtained via the
surfactant-assisted hydrothermal method
Runping Jia (
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)
∗
and Kangsheng Zheng (
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)
School of Materials Science and Engineering, Shanghai Institute of Technology, Shanghai 201418, China
∗
Corresponding author: jrpchem@yahoo.com.cn
Received June 13, 2012; accepted August 7, 2012; posted online September 28, 2012
Fishb one-like PbMoO
4
nanostructures are successfully obtained via the surfactant-assisted hydrothermal
method at 160
◦
C. Polyethylene glycol (PEG2000) is used as the template agent. The nanostructures are
characterized via X-ray diffraction, field-emission scanning electron microscopy, Fourier transform infrared
spectroscopy, ultraviolet-visible light (UV-Vis) spectroscopy, and photoluminescence (PL) measurements.
The PbMoO
4
morphology is highly associated with the molecular nature of PEG2000. PbMoO
4
nanopar-
ticles obtained from PEG2000 have a fishbone-shaped, scheelite-type tetragonal structure, in which nu-
merous secondary branches vertically grow on both sides of the main stem. The structures exhibit broad
PL emission bands with the maximum at 306 and 390 nm when excited at 250 nm. In addition, the UV-V is
absorption edge of the structures is in the 280 to 310 nm region, and the band gap is 4.07 eV. A plausible
formation mechanism for the fishbone-like PbMoO
4
nanostructures is also discussed.
OCIS codes: 160.2540, 160.4236, 160.4670.
doi: 10.3788/COL201210.111603.
The scheelite -type family of molybdates and tungstates
has been extensively investigated to obtain new func-
tionalities and behaviors associated with a broad range
of proper ties
[1−3]
. Lead molybdate (PbMoO
4
) belongs
to this family and is a promising material for industrial
applications such as acoustic-optical deflectors, modula-
tors, ion c onductors, and low-temperature scintillators
in nuclear instruments
[4−7]
.
In the past decades, PbMoO
4
crystals were prepared
mainly via the solid-state reaction and Czochralski crys-
tal growth, which usually require complex experimental
procedures, sophisticated equipment, and harsh synthe-
sis conditions
[8,9]
. Recently, the controlled synthesis of
molybdate crystallites with desirable shapes, sizes, and
crystal structures have become of considera ble interest
because of its wide range of technological applications
[10]
.
Several wet-chemical solution metho ds such as microwave
irradiation have been developed. However, some of
these methods have verified serious problems, including
polydispe rsed particle size distribution and unco ntrolled
morphology
[11−13]
. Thus, the controllable synthesis of
PbMoO
4
crystals with homogenous and well-defined
morphologies via facile routes remains a s ignificant chal-
lenge.
Complex nanostructures have unique optical and elec -
tronic prope rties because of their morphologies and spa-
tial organization
[14,15]
. In this study, a novel, fishbone-
like PbMoO
4
nanostructure was synthesized via a sim-
ple polyethylene glycol (Mw 2000) (PEG2000)-induced
hydrothermal appro ach. PEG2000 is often used as a
template in nano- and microcrystal fabrication. These
distinct fishbone-like PbMoO
4
nanoproducts have po-
tential applications in the fabrication of electronic and
optoelectronic nanodevices.
For the hydrothermal reaction, the reagents were of
analytical grade and used as received. In a typical syn-
thesis, 11.124-g PbCl
2
and 9.67 8-g Na
2
MoO
4
·2H
2
O were
separately dissolved in 40-mL hot water and tra nsferred
into two separate 100-mL flasks. Water was then added
to the graduation mark to obtain 0.4 mol/L solutions.
Afterward, 3 mL of the as-prepared PbCl
2
solution,
0.2-g PEG2000, and 30-mL water were successively
added into a 50-mL fla sk under vigorous stirring. An
equimolar Na
2
MoO
4
solution was then added into the
mixture, which was subsequently ultrasonically treated
for 30 min (freq uency, 40 kHz). The resulting white so-
lution was transferred into a 50-mL Teflon-lined stainless
steel autoclave. The seale d tank was heated to 160
◦
C
and maintained at this tempera tur e for 4 h without shak-
ing or stirring. The solution was then collected and nat-
urally cooled to room temper ature. The resulting white
precipitate was washed three times with distilled water
and absolute alcohol to remove the reactant re sidues and
then preserved in absolute alcohol for further character-
ization.
The crystalline phase was identified via X-ray
diffraction (XRD) using a Rigaku D/max2550
diffractometer with Cu- Kα radiation (λ = 0.15418 nm).
The sample morphology was observed under an FEI
Quanta 20 0F field- emission scanning ele c tron micro-
scope (SEM). The Fourier transform infrared (FTIR)
sp e ctra of KBr powder-pressed pellets were recorded
with a Nicolet NEXUS870 FTIR sp e ctrometer (USA).
Photoluminescence (PL) and UV-visible light (UV-Vis)
sp e ctra were obtained us ing a Perkin-Elmer lumines-
cence spectrophotometer (LS-55, USA) and an Agilent
8453 UV- Vis spectro photometer, respectively.
The as-synthesized product was first analyzed via
SEM. The corresponding low- and high-magnification
SEM images are shown in Fig. 1. The low-magnification
image of the product (Fig. 1(a)) shows an interesting
fishbone-like morpholo gy, with no trace of any other
morphology. The high-magnification SEM images (Figs.
1(b) and 1 (c)) verify this morphology. Figure 1(c) shows
1671-7694/2012/111603(4) 111603-1
c
2012 Chinese Optics Letters
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