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1.
BaMgAl10O17:Eu2+ (BAM:Eu) is widely used as a blue phosphor for fluorescent lamps and plasma display panels (PDP). The improvement of the luminescence efficiency is a significant issue for applications in plasma display panels. In this study, the Aerosol Flame Deposition (AFD) was applied to fabricate BaMgAl10O17:Eu2+ (BAM:Eu) particles with spherical shape and fine size in order to improve their luminescence. The sub-micrometer powder was synthesized in spherical shape in an oxy-hydrogen flame and deposited on a substrate in the form of porous film. The particle size of as-prepared powder increased with increasing the concentration of precursor solution and the heat treatment under reducing atmosphere increased particle size additionally with surface roughening due to the needle-like crystallized phases. Photoluminescence spectrum was observed at about 450nm due to the 5d–4f transition of Eu2+ and the intensity of phosphor was as high as 70% of that of the commercial phosphor. 相似文献
2.
Kyung-Hoon Cho Kyoung-Pyo Hong Sahn Nahm Bo-Yun Jang Joo-Seok Park Soon-Jae Yoo 《Journal of Electroceramics》2009,22(1-3):98-104
A homogeneous Eu2W2O9 phase with small grains (~4.0μm) was formed for the specimens fired below 1175°C. As the firing temperature was increased above 1150°C, grain growth occurred and the grain shape changed from faceted to round. The excitation spectra of the Eu2W2O9 phosphor were similar to those of the Eu2(WO4)3 phosphor, but the absorption band due to the O2?→W6+ ligand to metal charge transfer was shifted to lower energies and the 7Fo→5H3 and 7Fo→5F2,4 transitions were not found. The intensity of the excitation and emission spectra of the Eu2W2O9 phosphor considerably increased with increasing firing temperature, due to the increased grain size and changed grain shape. The intensity of the red emission band of the Eu2W2O9 phosphor was higher than that of the Eu2(WO4)3 phosphor. Moreover, the addition of LiCl to the Eu2W2O9 phosphors considerably enhanced the intensity of their emission spectra, probably due to the increased grain size. Therefore, LiCl-added, Eu2W2O9 phosphor is a promising candidate material for red color emission. 相似文献
3.
Sei-Ki Kim Mi-Jae Lee Jong-Hoo Paik Byung-Hyun Choi 《Journal of Electroceramics》2006,17(2-4):319-322
Photoluminescence and photocurrent characteristics of Eu2 + activated MAl2O4 (M = Ba, Ca, Sr) phosphors during and after Ultraviolet ray and visible light irradiation have been investigated. The photoluminescence
(PL) and the photocurrent (PC) of the phosphors, in order to elucidate the relationship between the PL and the PC, were measured
simultaneously on the same samples within a specially designed measuring box. Composition effects, such as a presence of Dy3 + as a co-activator and Al-rich composition on the PL and PC characteristics have been investigated. Also, sensing characteristics
on UV and visual light have been tested.
The simultaneous measurement of PL and PC on the same sample clearly indicated that the presence of co-activator and vacant
site, namely Al-rich composition, acted as a hole trap; the introduction of co-activator and vacant site decreased the PC
and increased the PL during and after UV and visible light irradiation, whose PC was much lower than that of MAl2O4 with only Eu2 + as an activator. The electrical intensity affected on the PL characteristics after UV and visual light irradiation(afterglow);
with increasing in the electrical intensity, the afterglow lasted more longer and intensively. The PC of MAl2O4 showed a good proportional relationship to UV and visible light intensity. Especially, SrAl2O4 showed an excellent linearity within 1–5 mW/cm2, but showed somewhat delayed response and hysterisis as seen in CdS photoelectric cell. 相似文献
4.
Di-calcium magnesium silicate phosphor doped with Eu2+ and Dy3+ was prepared using solid state reaction technique under a reducing atmosphere. Prepared sample suffered an impulsive deformation with an impact of a piston for mechanoluminescence (ML) investigations. A temporal characteristic of ML of the phosphor was observed, which expressed single sharp peak with a long decaying section. In order to investigate about the luminescence centre responsible for ML peak, ML spectrum of the same phosphor was also observed. ML spectrum recorded shown similarity in shape as well as peak wavelength with Photoluminescence (PL) spectrum that verifies the existence of single emission centre due to the transition of Eu2+ ions i.e. transitions from any of the sublevels of 4f65d1 configuration to 8S7/2 level of the 4f7 configuration. Decay rates for different impact velocities were also calculated using curve fitting technique. Time of ML peak and rate of decay did not change largely with respect to increasing impact velocity of the load and peak ML intensity varied linearly. Increasing impact velocity causes more number of Eu2+ ions to get excited to the higher energy level, subsequently de-excitation of more Eu2+ ions occurs. This gives rise to increase in ML intensity. 相似文献
5.
Dai-Hong Kim Choong Ki Lee Jun Seong Lee Seong-Hyeon Hong Young Jin Kim 《Journal of Electroceramics》2013,30(1-2):36-40
Eu2+ doped CaAl2O4 thin films were prepared on c-, a-, and r-plane sapphire substrates by a sputtering method, and then post-annealed for the recrystallization. Post-annealed films have out-of-plane epitaxial orientations of (010) and (001) CaAl2O4 on c- and a-plane sapphire substrates, respectively, whereas the films on r-plane were composed of two epitaxial phases of (210) CaAl2O4 and (210) CaAl4O7. In-plane relationships between films and substrates were also determined by an X-ray pole figure method, demonstrating that the films were epitaxially recrystallized, but not single crystals. The emission wavelengths were independent of the orientations of epitaxial films, showing a blue emission at 448 nm under 325 nm excitation, but the emission intensity depended on the film structure. 相似文献
6.
AbstractNovel Eu3+-activated orthosilicate NaYSiO4:xEu3+ (x?=?0.02, 0.05, and 0.20) red-emitting phosphors were developed for white light emitting diode applications. The X-ray diffraction (XRD), photoluminescence excitation and emission spectra, temperature-dependent curves were applied to characterize the samples. The red emission of the NaYSiO4:Eu3+ phosphor corresponding to 5D0→7F2 (614?nm) transition was observed under the excitation of 394?nm wavelength, which is suitable for UV LED chip. The quenching temperature for NaYSiO4:0.05Eu3+ was found to be over 500 K. The CIE chromaticity coordinates of NaYSiO4:0.05Eu3+ are very close to the National Television System Committee (NTSC) standard red. 相似文献
7.
Sung Park Yun-Joong Chung Jae Chun Lee Kang Yoo Byoung-Woo Kim Ju-Hyeon Lee 《Journal of Electroceramics》2006,17(2-4):827-830
ZnGa2O4 phosphors were synthesized by both SCM (solution combustion method) and SSRM (solid state reaction method). The characteristics
of the both ZnGa2O4 phosphors were investigated by TGA (Thermogravimetric analysis), SEM (scanning electron microscope), BET (Brunauer Emmett
Teller), PL (photoluminescence) and XRD (X-ray diffraction). The particle size of SCM phosphor was about one-hundredth of
SSRM phosphor. The PL intensity of SCM phosphor was about 1.5 fold higher than that of SSRM phosphor. The SCM phosphor was
also tried to be doped with Mn+2 ions. The highest PL peak was observed with Mn+2 ions of 0.003 mole fraction. The peak was shifted from blue (470 nm) to green (513 nm) color. These results might be very
useful for high efficiency phosphors for displays such as field emission displays and plasma display panels. 相似文献
8.
9.
解决单质硫导电性问题是提高锂硫电池性能的关键。纳米氧化物不仅能提高硫电极的孔隙度,还能吸附较多硫离子,对电池的氧化还原反应起到催化作用。研究了纳米氧化物Al_2O_3对单质硫电化学性能的影响,并采用X射线衍射光谱法(XRD)、扫描电子显微镜法(SEM)、粒度分析仪对电池材料物相、颗粒形貌和粒度分布进行表征。利用高精度电池性能分析测试系统对正极材料、电池进行电性分析。 相似文献
10.
Kazumi Kato 《Integrated ferroelectrics》2013,141(1-4):93-100
Abstract The crystallographic orientation, microstructure and electrical properties of Sr2(Ta, Nb)2O7 thin films strongly depended on the composition (Ta:Nb). Post-annealing at 850°C was effective for the improvement of some properties. The thin films with relatively Nb-rich compositions, such as Sr2(Ta0.6Nb0.4)2O7 and Sr2(Ta0.5Nb0.5)2O7, showed the (0k0) preferred orientation. The Sr2(Ta0.5Nb0.5)2O7 thin film had a lamination layer structure after the post-annealing at 850°C for 6 min in oxygen. The characteristic microstructure originated in the crystallographic orientation of (0k0), which is the cleavage plane, and influenced electrical properties. The dielectric constant little change with the composition, however, the P-E hysteresis properties improved with the Nb content. 相似文献
11.
The luminescent properties of BaMgAl10O17: Eu2+ blue phosphor are closely related to the valence state of europium inside the crystal and its defect structure. Because of the complexity of the BAM structure, research was carried out to study the europium-related defects by computer simulation. Two different Mg distributions were found to have the same lattice energy, but the arrangement of Mg affected the defect energy and Eu position. Eu3+ behavior was also discussed to address the oxidation-induced luminescent degradation. Two energetically most-favorable positions were found for europium, depending on the oxidation state: the Beevers-Ross site on the conduction plane for Eu2+, and the Al(2) site in the middle of the spinel block for Eu3+. Results of defect complex and bond-valence calculations suggested that the large europium ion can reside in the oxygen close-packed spinel blocks. A comparison of europium defect properties calculated with two different potential models suggests that results of the simulations are potential independent. 相似文献
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14.
AbstractThe europium doped Sr2SiO4 phosphors were prepared by the combustion synthesis technique. The prepared samples of europium doped Sr2SiO4 phosphors were characterized by the X-Ray Diffraction (XRD), Ultraviolet Visible spectroscopy (UV), Fourier Transform Infrared Spectroscopy (FT-IR), Field Emission Scanning Electron Microscopy (FE-SEM), Energy Dispersive Spectra (EDS) and Photoluminescence Technique (PL). The orthorhombic crystal structure of the prepared sample was confirmed by using XRD. The formation of fiber like nano structured nature was confirmed by the images captured using the FE-SEM technique. The band gap energies were calculated using the UV-Visible spectra of the samples and these band gap energies were observed as 4.5826?eV for Sr2SiO4 and 4.1748?eV for Eu (5?m%) doped Sr2SiO4. The two different PL emission peaks were observed for two different excitation wavelengths. One peak was observed at the 590?nm under 393?nm excitation and another peak was observed at the 615?nm under 408?nm excitation. The CIE color coordinates of the Eu3+ doped Sr2SiO4 phosphors are x?≈?0.6615, y?≈?0.3382 (red color) observed for 408?nm excitation and x?≈?0.5636, y?≈?0.4356 (orange) observed for 393?nm excitation calculated using the color calculator program radiant imaging. 相似文献
15.
In this paper, effect of synthetic conditions on the particle size, crystal structure, and the photoluminescence properties
of the Y2O3:Eu3+ nanophosphor was investigated. Solvent and dispersing agent were determined as the synthetic parameters. The nanophosphor
synthesized from methanol solvent showed the smaller particle size of 4 nm. The XRD analysis indicates that the crystal structure
of the Y2O3:Eu3+ nanophosphor is mainly cubic crystal with orientation of (222), (440), (400), and small peak of (511) indicating monoclinic
crystal. The Y2O3:Eu3+ nanophosphor synthesized by using methanol solvent and 0.1 wt.% hydroxypropyl cellulose (HPC) as a dispersing agent showed
higher degree of crystallization of 10.5 of I
(222)/I
(511) ratio than that without HPC. Also, the photoluminescence properties of the nanophosphor showed red color that excitation
and emission wavelengths of the nanophosphor were 250 and 611 nm, respectively. Using the 250 nm UV source, the highly intensive
photoluminescence peak could be achieved at 611 nm under the synthetic condition of methanol solvent adding 0.1 wt.% HPC. 相似文献
16.
Itaru Tsutai Takuya Kamimura Keizo Kato Futao Kaneko Kazunari Shinbo Masatoshi Ohta Takahiro Kawakami 《Electrical Engineering in Japan》2000,132(1):7-14
SrAl2O4 activated with Eu, a new fluorescent material having a long decay time, was deposited on Si substrates using an RF sputtering technique with facing targets. The as‐deposited films did not show any peaks in the X‐ray diffraction spectra and no photoluminescence was observed. However, X‐ray diffraction peaks and a photoluminescent peak at about 520 nm were observed after annealing in a reducing Ar+H2 gas and an inert Ar gas. The structure of the sputtered films was investigated using EDS and SEM. The thermoluminescence peaks were observed, and the lifetime of the fluorescence and the activation energies were calculated from the peaks. The results in this work are useful for future applications. © 2000 Scripta Technica, Electr Eng Jpn, 132(1): 7–14, 2000 相似文献
17.
Noboru Yoshimura Masashi Itoi Shigeki Sato Haruo Taguchi 《Electrical Engineering in Japan》1992,112(5):10-16
A TiO2 thin film was prepared by the sol-gel method using a metal alkoxide [Ti(O-i-Pr)4 tetrasopropoxy titanium: TIPT]. The crystalline form of the film depends on the preparation conditions and the heat treatment temperature. When the ratio (γ) of H2O to TIPT is 7, the crystalline phase is formed at 400°C; when γ = 2 it is formed at 500°C. The anatase crystal structure was obtained for both γ = 2 and γ = 7. The electrical conductivity of the TiO2 film increased with the heat treatment temperature. 相似文献
18.
Yong Eui Lee David P. Norton John D. Budai Christopher M. Rouleau Jae-Won Park 《Journal of Electroceramics》2000,4(2-3):293-297
The epitaxial growth and properties of Mn2+-doped ZnGa2O4 thin films on various single crystal substrates using pulsed laser deposition were investigated. Control of Zn/Ga stoichiometry required the use of a mosaic ZnGa2O4/ZnO ablation target to compensate for Zn loss due to evaporation. The photoluminescent intensity was a strong function of the Zn/Ga ratio, and also correlated with changes in the surface morphology. Superior photoluminescent intensity was attained from slightly Zn-deficient films which exhibit distinctive worm-like surface features. Enhanced photoluminescent intensity was observed in epitaxial films as compared to randomly-oriented polycrystalline deposits on glass substrates, suggesting an adverse effect of grain boundaries on luminescence properties. 相似文献
19.
LiMn2O4的甘氨酸法合成 总被引:2,自引:0,他引:2
用甘氨酸法合成锂锰氧化合物,通过FTIR、NMR和TG/DTA等研究了锂锰.甘氨酸前驱体的组成、结构和锂锰氧化舍物的形成机理,并对LiMn2O4样品进行XRD分析.甘氨酸法可在低温下反应,得到原子级水平混合的锂离子与锰离子前驱体;在356℃左右就可得到尖晶石LiMn2O4;在400℃下煅烧合成的样品以纯尖晶石LiMn2O4存在,在750℃下煅烧合成的LiMn2O4样品,0.2 C首次放电比容量为119.8 mAh/g,20次循环后放电比容量为118.4 mAh/g. 相似文献
20.
Ruirui Cui Chaoyong Deng Xinyong Gong Xucheng Li Jianping Zhou 《Journal of Electroceramics》2014,32(2-3):215-219
The CaBi2Ta2O9 bismuth layered-structure ferroelectrics doped with rare earth ions Eu3+ and Tb3+, or co-doped with Eu3+/Tb3+ were prepared by the conventional solid-state reaction method. The microstructure and photoluminescence properties of CaBi2Ta2O9: Eu3+, CaBi2Ta2O9: Tb3+ and CaBi2Ta2O9: Eu3+/Tb3+ were investigated. The XRD patterns demonstrate that the rare earth ions have been effectively doped into CaBi2Ta2O9 host lattices. The photoluminescence properties of CaBi2Ta2O9 with different activator ions are researched in details. The novel red and green light emissions were observed under the excitation of blue and near-UV light. Notably, tunable emissions and a warm-white color have been achieved in the Eu3+ and Tb3+ co-doped CaBi2Ta2O9 powders. These results suggest that CaBi2Ta2O9: Eu3+, CaBi2Ta2O9: Tb3+ and CaBi2Ta2O9: Eu3+/Tb3+ could be novel luminescence materials. It is also expected that rare earth doped CaBi2Ta2O9 ferroelectrics can find potential applications in new multifunctional photoluminescence ferroelectric devices. 相似文献