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1.
Zn2SiO4:Tb nanoparticles were prepared by sol-gel-microwave heating for the first time. X-ray powder diffraction (XRD) analysis confirmed
the formation of Zn2SiO4 in willemite structure. Field-emission scanning electron microscopy showed a narrow size distribution, small size (40–50 nm)
and spherical shape of the particles. Energy dispersive spectroscopy result indicated that the ratio of Tb3+/Zn2+ was in agreement with that of the feed. Photoluminescence measurement indicated that the phosphor emitted strong green light
centered at 545 nm under UV light excitation. The excitation spectra confirmed the energy transfer from the host material
to the Tb3+ ions. This is in favor of the effective green emission of Zn2SiO4:Tb nanoparticles. 相似文献
2.
Jinsheng Liao Bao Qiu He-Rui Wen Yong Li Ruijin Hong Hangying You 《Journal of Materials Science》2011,46(5):1184-1189
Monodispersed spheres (1–4 μm in diameter) of BaWO4:Eu3+ (hereafter BWO:Eu) red-phosphor exhibiting intense emission at 615 nm were synthesized via a mild hydrothermal method. X-ray
diffraction, scanning electron microscope, photoluminescence excitation and emission spectra, and decay curve were used to
characterize the properties of BWO:Eu phosphors. An intense red emission was obtained by exciting either into the 5L6 state with 394 nm or the 5D2 state with 465 nm, that correspond to two popular emission lines from near-UV and blue LED chips, respectively. The values
of Ω
2,4 experimental intensity parameters (13.8 × 10−20 and 8.2 × 10−20 cm2) are determined. The high-emission quantum efficiency of the BWO:Eu phosphor suggests this material could be promising red
phosphors for generating white light in phosphor-converted white light-emitting diodes. 相似文献
3.
Aksana Zharkouskay Heinrich Lünsdorf Claus Feldmann 《Journal of Materials Science》2009,44(15):3936-3942
Luminescent YVO4:Eu nanocrystals were prepared via an ionic liquid-based synthesis. According to electron microscopy, dynamic light scattering,
and X-ray diffraction, the presence of uniform and highly crystalline particles, 12–15 in diameter is validated. As-prepared
particles turn out to be nonagglomerated and redispersible. Photoluminescence exhibits characteristic red emission related
to Eu3+. Quantum yield of as-prepared YVO4:Eu (15 mol%) is determined to 17–19%. The quantum yield of as-prepared material increases to 44–46% by establishing an YVO4:Eu@YF3 core-shell structure. Since the lattice planes (001) of YVO4 and (100) of YF3 match very well, a crystalline YF3 shell, 1–2 nm in thickness protects the YVO4 core very efficiently. Besides the significantly increased quantum yield, the presence of a core-shell structure is further
evidenced by electron energy loss spectroscopy. Element mapping revealed high intensities of Eu in the inner parts, associated
with low peripheral fluorine intensities.
相似文献
4.
Haike Ren Fugui Yang 《Journal of Materials Science: Materials in Electronics》2018,29(18):15396-15403
The Mn2+, Yb3+, Er3+: ZnWO4 green phosphors are synthesized successfully through the high temperature solid state reaction method. The micro-structure and morphology have been investigated by means of XRD and EDS. The doped concentrations of Mn2+, Yb3+, Er3+ are measured by ICP. The absorption spectra and emission spectra with different doped concentrations of Mn2+ are presented to reveal the influence of Mn2+ on the green up-conversion performance. Excited with 970 nm LED, the up-conversion emission peak at 547 nm is obtained and the CIE spectra as well as the green light photo are also presented. The results indicate that the Mn2+ ions play the role of the luminescence adjustment in the up-conversion process, which can improve the up-conversion green emission intensity effectively. The luminescence adjustment mechanism of Mn2+ ions in Mn2+, Yb3+, Er3+: ZnWO4 green phosphors has been discussed. The crystal parameters of Dq, B and C are calculated to evaluate the energy level split effect. 相似文献
5.
Runping Jia Qingsheng Wu Guoxin Zhang Yaping Ding 《Journal of Materials Science》2007,42(13):4887-4891
For the first time, a novel route for preparing AWO4 (A=Zn, Cd) nanofilm on a glass substrate is proposed through the combination of reverse micelle system with dip-coating technology.
Here collodion is used as a dispersant and film-forming agent to obtain nanofilm with a good quality and property. SEM and
XRD results indicate ZnWO4 and CdWO4 nanoparticles with monoclinic system and wolframite structure are well dispersed on the substrate. The nanofilm’s photoluminescent(PL)
bands obviously blue shift compared with bulk materials whereas red shift compared with nanoparticles, which should be due
to quantum size effect and film-forming effect. FTIR absorption bands between 400 and 900 cm−1 prove the presence of ZnWO4 or CdWO4 nanoparticles on the substrate. 相似文献
6.
A new efficient phosphor, Eu2+/Eu3+ and Ce3+ activated Na2Zn5(PO4)4 has been synthesized by solid-state reaction technique at high temperature. X-ray powder diffraction analysis confirmed the
formation of Na2Zn5(PO4)4 host lattice. Scanning electron microscopy indicated that the microstructure of the phosphor consisted of irregular fine
grains with a size of about 0·5–2 μm. Photoluminescence excitation spectrum measurements of Ce3+ activated Na2Zn5(PO4)4 show that the phosphor can be efficiently excited by UV-Vis light from 280 to 310 nm to realize emission in the visible (blue)
range due to the 5d-4f transition of Ce3+ ions which is applicable for scintillation purpose, whereas Eu2+/Eu3+ activated Na2Zn5(PO4)4 phosphor emits blue, green and red emission spectrum shows at 487 nm, 546 nm with a dominant peak at 611 nm respectively,
due to Eu2+/Eu3+ ions which is promising candidate for solid state lighting. Therefore, newly synthesised, by low cost and easy technique
prepared, novel phosphors may be useful as RGB phosphor for solid state lighting application. 相似文献
7.
V. P. Dotsenko I. V. Berezovskaya N. P. Efryushina A. S. Voloshinovskii G. B. Stryganyuk 《Journal of Materials Science》2010,45(6):1469-1472
The luminescence properties of Sm3+ ions in YAl3B4O12 were studied upon synchrotron excitation in the 3.8–11 eV region. In addition to the 4f → 4f excitation bands, the excitation spectra of the Sm3+ emission contain broad bands at 6.1 and ~7.0 eV. These bands are attributed to charge transfer transition in Sm3+–O2− complexes and 4f → 5d transition of Sm3+ ions, respectively. The optical absorption edge of YAl3B4O12 was determined at 7.3 eV. A comparison with the results of electronic structure calculations on YAl3B4O12 is also made. 相似文献
8.
Y. Y. Zhang J. L. Liu Y. X. Zhu Y. Shang M. Yu X. Huang 《Journal of Materials Science》2009,44(13):3364-3369
Nanocrystalline SrCO3:Tb3+ phosphor layers were coated on monodisperse and spherical polystyrene particles by a typical hydrothermal synthesis without
further annealing treatment, resulting in the formation of core-shell-structured polystyrene@SrCO3:Tb3+ particles. X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, photoluminescence,
as well as lifetimes were employed to characterize the resulting composite particles. Under ultraviolet excitation, the polystyrene@SrCO3:Tb3+ phosphors show the characteristic 5D4–7F
J
(J = 6, 5, 4, 3) emission lines with green emission 5D4–7F5 (544 nm) as the most prominent group. The obtained core-shell phosphors are potentially applied in fluorescent lamps. 相似文献
9.
Vijay Singh R. P. S. Chakradhar J. L. Rao Ho-Young Kwak 《Journal of Materials Science》2011,46(7):2331-2337
An efficient red emitting ZnAl2O4:Cr3+ powder phosphor material was prepared at furnace temperatures as low as 500 °C by using the combustion method. The prepared
powders were analyzed by X-ray diffraction and scanning electron microscopy techniques. The optical properties were studied
using photoluminescence technique. The EPR spectra exhibit an intense resonance signal at g = 3.74 which is attributed to Cr3+–Cr3+ pairs, and the weak resonance signal of at g = 1.97 is attributed to Cr3+ single ion transition. The spin population (N) has been evaluated as a function of temperature. The excitation spectrum exhibits two broad bands in the visible region
which are characteristic of Cr3+ ions in octahedral symmetry and the emission spectrum exhibits zero-phonon line frequencies along with vibronic frequencies.
The crystal field parameter (Dq) and Racah parameters (B and C) have been evaluated and discussed. 相似文献
10.
P. J. Purohit M. Mohapatra V. Natarajan S. V. Godbole 《Journal of Materials Science》2011,46(7):2030-2035
Synthesis, X-ray diffraction, and photoluminescence (PL) investigations of SrZnO2 doped with Eu3+ were carried out in order to characterize the material. The emission spectra showed a broad band emission at 525 nm attributed
to oxygen defect centers in the host matrix, along with peaks corresponding to the 5D0 → 7F
j
(j = 1, 2) transitions of Eu ion under 250 nm excitation. PL decay time studies were done to confirm these investigations. Time-resolved
emission spectrometric (TRES) study was carried out to extract the emission spectra of the Eu ion which was buried under the
broad band emission. After giving suitable delay times and by choosing a proper time gate, transitions due to 5D0 → 7F
j
(j = 0, 1, 2, 3, and 4) could be observed. Judd–Ofelt intensity parameters and other radiative properties for the system were
evaluated from this emission spectrum and decay time data by adopting standard procedure. The color coordinates of the system
were also evaluated and plotted on a standard CIE index diagram. The observations showed that the SrZnO2:Eu3+material has near white light emission (also considering the emission from host) whereas, the extracted emission spectrum
due to only Eu ions has a near red emission. 相似文献
11.
Zhouyun Ren Chunyan Tao Hua Yang 《Journal of Materials Science: Materials in Electronics》2008,19(4):319-321
YAl3(BO3)4:Tb3+ phosphors were fabricated by the sol–gel method. The phosphor showed prominent luminescence in green due to the magnetic
dipole transition of 5D4–7F5. Structural characterization of the luminescent material was carried out with X-ray powder diffraction (XRD) analysis. Luminescence
properties were analyzed by measuring the excitation and photoluminescence spectra. Photoluminescence measurements indicated
that the phosphor exhibited bright green emission at about 541 nm under UV excitation. It is shown that the 11% of doping
concentration of Tb3+ ions in YAl3(BO3)4:Tb3+ phosphors is optimum. 相似文献
12.
Zhike Liu Yajun Qi Chaojing Lu 《Journal of Materials Science: Materials in Electronics》2010,21(4):380-384
Single-crystalline BiFeO3 nanoparticles have been synthesized through a simple chemical coprecipitation process using bismuth and iron nitrates. By
employing both X-ray diffraction and electron diffraction, the nanoparticles were unambiguously identified to have a rhombohedrally distorted perovskite structure. X-ray photoelectron spectroscopy investigation shows
that Fe element exists as the Fe3+ valence state in the BiFeO3 nanoparticles. UV–Vis absorption spectrum indicates that the absorption cut-off wavelength of the nanoparticles is about
580 nm, corresponding to the energy bandgap of 2.10 eV. The BiFeO3 nanoparticles exhibited an efficient ultraviolet photocatalytic activity, more than 92% of methyl orange was decolorized
after 260 min UV irradiation. Unexpectedly, the BiFeO3 nanoparticles do not show any efficient visible light photocatalytic activity, although the nanoparticles absorb visible
light in the wavelength range of 400–580 nm. 相似文献
13.
Emission spectral results of Pr3+ & Ho3+ ions doped Ca4GdO(BO3)3 powder phosphors are reported here. XRD, SEM and FTIR measurements have been carried out for them. The emission spectrum
of Pr3+: Ca4GdO(BO3)3 has shown an emission transition 1D2 → 3H4 at 606 nm with λexci = 480 nm (3H4 → 3P0) and Ho3+: Ca4GdO(BO3)3 phosphor has shown an emission transition 5S2 → 5I8 at 549 nm with λexci = 447 nm (5I8 → 5F1). Emission performances of these two phosphors have been explained in terms of energy level diagrams. 相似文献
14.
Linhui Gao Yue An Hongliang Zhu Lun Wang Jianjun Chen Naiyan Wang Guofu Ou 《Journal of Materials Science》2011,46(5):1337-1340
This article presents the synthesis and photoluminescence (PL) properties of Y2Zr2O7:Tb3+. The Tb3+-doped Y2Zr2O7 zirconates were successfully synthesized by a hydrothermal process at 200 °C for 20 h. X-ray diffractometer (XRD) patterns
revealed that all of the products were phase-pure with the fluorite structure. PL study showed that the Y2Zr2O7:Tb3+ phosphors exhibited obvious PL emission peaks which located at 490, 545, 585, and 623 nm; the dominant emission located at
545 nm is assigned to 5D4 → 7F5 transition. Furthermore, Tb3+-doping concentration strongly affected the PL properties, and the quenching concentration is 5 at.%. 相似文献
15.
Xiang-Hong He Ming-Yun Guan Jian-Hua Sun Ning Lian Tong-Ming Shang 《Journal of Materials Science》2010,45(1):118-123
LiEu1−x
(W2−y
Mo
y
)O8:xBi3+ series red-emitting phosphors were synthesized by solid state reaction. The structure, morphology, and photoluminescent properties
of phosphors were studied by X-ray powder diffraction, scanning electron microscopy, and photoluminescence spectrum, respectively.
X-ray powder diffraction analysis showed that the as-obtained phosphors belong to the scheelite structure. The average particle
size of the investigated phosphor was about 8 μm. The excitation spectrum exhibits a charge-transfer broad band along with
some sharp peaks from the typical 4f–4f transitions of Eu3+. Under excitation of UV, near-UV, or blue light, these phosphors showed strong red emission at 615 nm due to 5D0–7F2 transition of Eu3+. The incorporation of Mo6+ into LiEuW2O8:Bi3+ could induce red-shift of the charge-transfer broad band and a remarkable increase of photoluminescence. The highest red-emission
intensity was observed with LiEu0.80Mo2O8:0.20Bi3+. Compared with the commercial red-emitting phosphor, Y2O2S:Eu3+, the emission intensity of LiEu0.80Mo2O8:0.20Bi3+ phosphor is much stronger than that of Y2O2S:Eu3+ and its chromaticity coordinates are closer to the standard values than that of the commercial phosphor. The optical properties
of LiEu0.80Mo2O8:0.20Bi3+ phosphor make it attractive for the application in white-light-emitting diodes (LEDs), in particular for near-UV InGaN-based
white-LEDs. 相似文献
16.
P. Sivakumar R. Ramesh A. Ramanand S. Ponnusamy C. Muthamizhchelvan 《Journal of Materials Science: Materials in Electronics》2012,23(5):1011-1015
NiFe2O4 nanoparticles are prepared by a simple and cost-effective method using via polyvinyl alcohol assisted sol–gel auto-combustion
method. The X-ray diffraction result indicated that the synthesized nanoparticles have only the inverse spinel structure without
the presence of any other phase impurities. HR-SEM and TEM images showed that the particles are spherical shape with particle
size in the range ~11 nm. The magnetic property of these nanoparticles is studied for the enlightening ferrimagnetic behaviour
at room temperature. The value of the magnetic saturation (Ms) is 44.3 emug−1, remanent magnetization (Mr) is 19.8 emug−1 and coercive force (Hc) is 672.02 Oe. 相似文献
17.
Ehsan Shafia Alireza Aghaei Masoud Bodaghi Mohammadreza Tahriri 《Journal of Materials Science: Materials in Electronics》2011,22(8):1136-1142
In this research, we reported the synthesis of Eu2+ and Dy3+ co-doped SrAl2O4 phosphor nanopowders with high brightness and long afterglow by urea-nitrate solution combustion synthesis (SCS) at 600 °C,
followed by heating the resultant combustion ash at 1,200 °C in a weak reductive atmosphere (5% H2 + 95% N2). The broad-band UV-excited luminescence of the SrAl2O4: Eu2+, Dy3+ nanopowders was observed at λ
max = 517 nm due to transitions from the 4f65d1 to the 4f7 configuration of the emission center (Eu2+ ions). The excitation spectra consist of 240- and 254 nm broad peaks. Finally, it was found that the optimum ratio of urea
is 2.5 times higher than theoretical quantities for the best emission condition of SrAl2O4: Eu2+, Dy3+ phosphor nanopowders. 相似文献
18.
Kehui Qiu Junfu Li Junfeng Li Xueguang Lu Yingchun Gong Junhan Li 《Journal of Materials Science》2010,45(20):5456-5462
Red emitting phosphor Ca3(VO4)2:Eu3+ was prepared by citric acid-assisted solution combustion method and characterized by X-ray diffraction (XRD), transmission
electron microscopy (TEM), and fluorescence spectrophotometer. The influences of Ca to V molar ratio and synthesis temperature
on phase composition, morphology, grain size, photofluorescence properties, and ultraviolet–visible diffuse reflectance spectra
(UV–Vis DRS) of as-synthesized samples were investigated. The results indicate that Ca to V molar ratio play a key role for
the changing of phase composition, excitation spectrum, and luminescence intensity. The sample prepared at 900 °C, keeping
Ca/V = 3:2.2, has the highest photoluminescence intensity. The possible causes of the effects on photoluminescence mechanism
were also discussed in this work. 相似文献
19.
Tanggang Li Suwen Liu Haiping Zhang Enhua Wang Lingjun Song Ping Wang 《Journal of Materials Science》2011,46(9):2882-2886
Infrared-to-ultraviolet upconversion luminescence agent Y2O3:Yb3+,Tm3+ was prepared by a combustion method using citrate as a fuel/reductant. The prepared sample was characterized by X-ray diffraction,
SEM, and fluorescence spectrophotometer. Two unusual 1I6 → 3H6 (~297 nm) and 1D2 → 3H6 (~363 nm) emissions from Tm3+ ions were observed at room temperature under 980-nm laser excitation. The change of upconversion emission intensity depending
on the Yb3+ concentrations was discussed. The results showed that modest Yb3+ doping could make the upconversion emission of Tm3+ intense, and high Yb3+ concentrations might lead to fluorescence quenching. Moreover, the influence of ultraviolet upconversion luminescence on
the photodegradation of methyl orange aqueous solution under solar light irradiation in the presence of TiO2 catalyst doped with Y2O3:Yb3+,Tm3+ was also investigated. It was concluded from the experiment of this study that TiO2/Y2O3:Yb3+,Tm3+ composite had higher photocatalytic activity than pure TiO2 under solar light. This study would make TiO2 utilize sunlight more efficiently and accelerate the practical application of photocatalytic technology in water treatment
region. 相似文献
20.
Xue Wang Chen Guo Hu Yi Xi Chuan Hui Xia Xiao Shan He 《Journal of Superconductivity and Novel Magnetism》2010,23(6):909-911
Al-doped Fe3O4 nanoparticles were synthesized for the first time via the Composite-Hydroxide-Mediated (CHM) method from Fe3O4 and Al2O3 without using any capping agent. The synthesis technique was one-step and cost effective. The obtained products were characterized
by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersion spectroscopy (EDS). Samples with a tunable
size of 500–1500 nm, 200–800 nm, and 100–700 nm could be obtained by adjusting the reaction time and temperature. Magnetic
property of the as-synthesized Al-doped Fe3O4 nanoparticles was investigated. Magnetic hysteresis loops measured in the field range of −10 kOe<H<10 kOe, indicated the ferromagnetic behavior with coercivity (H
c) of 470 and 110 Oe and remanence magnetization (M
r) of 13 and 6.4 emu/g at the temperature of 5 and 300 K, respectively. The saturation intensity (M
s) was 46.1 emu/g at 5 K, while it was about 43.6 emu/g at 300 K. 相似文献