Asian Journal of Chemistry; Vol. 27, No. 7 (2015), 2564-2566
A
SIAN
J
OURNAL OF HEMISTRY
C
3+
Synthesis, Characterization and Luminescent Properties of Green Phosphor BaMoO :Tb
4
1,*
1
1
2
JIANFU ZHANG , LILI ZHU , JIANPING XIE, YUANPENG CHEN and ZHENLING WANG
1
2
Department of Chemistry, Zhoukou Normal University, Zhoukou 466001, P.R. China
Applied Chemistry and Fine Chemical Engineering Technology Research Center of Zhoukou City, Zhoukou 466001, P.R. China
*
Received: 5 July 2014;
Accepted: 16 September 2014;
Published online: 30 March 2015;
AJC-17080
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The green phosphor BaMoO :Tb was prepared by sol-gel method. The effects of doping concentration and sintering temperature on the
4
crystal structure and luminescent properties were investigated by X-ray powder diffraction, scanning electron microscope, UV-visible
spectroscopy and photoluminescence spectroscopy. The XRD results showed a pure BaMoO phase can be obtained when calcinating
4
phosphor at 900 °C. The photoluminescence spectroscopy spectra exhibited four peaks, the most intense peak of 542 nm can be attributed
5
7
3+
3+
3+
to D
4
→ F
5
transition of Tb and the optimized mol percent of Tb was 0.05. All the results indicated that BaMoO : Tb could be used
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as a white-light emitting diodes ultraviolet photoexcitation green phosphors.
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Keywords: BaMoO : Tb , Sol-gel method, Green phosphors.
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mild reaction conditions, homodisperse, it is quite suitable for
INTRODUCTION
Light emitting diodes (LED) become the new luminous
synthesize thermal-unstable phosphors. Herein the green
3+
phosphor BaMoO
4
:Tb was prepared by the sol-gel method
1
st
sources in 21 century and are favored by the markets. To the
best of our knowledge, there are three approaches to obtain
and its photoluminescence properties were also investigated.
2,3
white light emitting diodes . The first one is multichip method,
by mixing red, green, blue lights which were emitted by the
corresponding chips in certain percent together. The second
one is the integrated single chip method, using a chip to directly
emit white light via a plurality of active layer. The third one,
which was attracted widespread attention for its high luminous
efficiency is the fluorescent conversion method, it combines a
phosphor with chip. The nature of phosphor plays an important
EXPERIMENTAL
Tb(NO
3
)
3
(0.1 mol/L), Na
2
MoO
4
·2H
2
O, analytical pure,
·2H O, analytical
CH O)nH,
bought from Tianjin Chemical Plant; BaCl
pure, bought from Kaifeng Chemical Plant; HO(CH
6000-7500, Tianjin BASF Chemical.
The structures of samples were characterized by X-ray
powder diffraction (XRD, German Bruker with CuK radiation,
λ = 0.15406 nm). The morphology of nanoparticles were
obtained by SEM (FEI Quanta 200 FEG, 40 kV, 150 mA, scan
range 15°-65°, scan rate 2°/min). The excitation and emission
spectra were recorded by Spectrophotometers (UV-visible
Perkin Elmer Lambda35 equipped with an integrating sphere,
2
2
2
2
α
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role on the luminescent properties . In recent decades, most
of the studies focused on molybdates- or tungstates-based red
5
2-
4
phosphors, rarely on other colours . MoO
can absorb near
ultraviolet light and blue light light emitting diodes and transfer
3
+ 6
3+
5
to rare earth ion Tb . Moreover, Tb shows efficient D →
5
4
7
F
transition under the excitation of green light, therefore, we
BaSO
Fluorescence Spectrometer).
PreparationofthesampleBaMoO
and BaCl ·2H O (stoichiometric ratio = 1:1) were dissolved
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was used for the reflection-background contrast; LS55
can get green phosphors via doping appropriate amount of
3+
7
Tb to the molybdates . This method has important signi-
ficance for the development and application of white light
emitting diodes.
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:Firstly, Na
2
MoO
4
·2H O
2
2
2
in deionized water under continuously stirring at room tempe-
rature until formed homogeneous solution, then stirred at 40 °C
for 0.5 h and filtrated, the transparent gel can be formed.
Secondly, the gel was transferred onto a surface plate and
maintained at 80 °C in drying oven for 2 h, then it became a
white glue. Finally, the white glue was divided into four
The synthesis of molybdate- or tungstate-based phosphors
was under high-temperature and solid-state, however some
drawbacks are very obvious, such as high reaction temperature,
low reaction rate, big size with irregular morphology. On the
contrary, the sol-gel method has many advantages, such as