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1.
Gd2Ti2O7: Eu3+ thin film phosphors were fabricated by a sol-gel process. X-ray diffraction (XRD), atomic force microscopy (AFM) and photoluminescence (PL) spectra as well as lifetimes were used to characterize the resulting films. The results of XRD indicated that the films began to crystallize at 800 °C and the crystallinity increased with the elevation of annealing temperatures. Uniform and crack free phosphor films were obtained, which mainly consisted of grains with an average size of 70 nm. The doped Eu3+ showed orange-red emission in crystalline Gd2Ti2O7 phosphor films due to an energy transfer from Gd2Ti2O7 host to them. Both the lifetimes and PL intensity of the Eu3+ increased with increasing the annealing temperature from 800 to 1000 °C, and the optimum concentrations for Eu3+ were determined to be 9 at.%. of Gd3+ in Gd2Ti2O7 film host. 相似文献
2.
Changliang Zhao 《Materials Letters》2007,61(17):3673-3675
Eu2+,Nd3+ co-doped calcium aluminate with high brightness and long persistent luminescence was prepared by the combustion method. The luminescent properties of CaAl2O4-based luminescent materials have been studied systematically. The phosphor powders were further investigated by X-ray diffractometer (XRD), photoluminescence excitation and emission spectra (PL) and brightness meter. The analytical results indicated that the phase of CaAl2O4 was formed when the initiating combustion temperature was 400 °C. The broad band UV excited luminescence of the CaAl2O4:Eu2+,Nd3+ was observed at the blue region (λmax = 440 nm) due to transitions from the 4f65d1 to the 4f7 configuration of the Eu2+ ion. The decay time of the persistence indicated that the persistent luminescence phosphor has bright phosphorescence and maintains a long duration. 相似文献
3.
Jiachi Zhang Zhiya Zhang Xie Peng Yanping Jiang Huihui Li 《Materials Research Bulletin》2009,44(4):953-5027
The novel vacuum ultraviolet (VUV) excited Na3Y9O3(BO3)8:Eu3+ red phosphor was synthesized and the photoluminescence (PL) properties were investigated. The phosphor showed strong VUV PL intensity, large quenching concentration (40 mol%) and good chromaticity (0.649, 0.351). The Eu3+-O2− charge transition (CT) was observed to be at a higher energy (232 nm, 5.35 eV). The host absorption at 127-166 nm was broad and strong when monitoring the Eu3+ emission, which indicated that energy transfer from the host-lattice to the Eu3+ ions was efficient in Na3Y9O3(BO3)8:Eu3+. These excellent VUV PL properties were revealed to be correlated with the unique isolated layer-type structure of Na3Y9O3(BO3)8 host. The results showed that the Na3Y9O3(BO3)8:Eu3+ would be a good candidate for VUV-excited red phosphor. 相似文献
4.
Hui Gao 《Materials Research Bulletin》2007,42(5):921-927
YAlO3 and YAlO3:Eu3+ powder phosphors were prepared by the citric-gel method, and the formation of purified crystalline phases of YAlO3 and YAlO3:Eu3+ was dependent on the pH value of the starting solution. The powders prepared with pH 3 yielded a single phase YAlO3 after calcinations at 1000 °C. The spectroscopic properties in UV-vacuum ultraviolet (VUV) range for the orthorhombic structure phosphors YAlO3:Eu3+ were investigated. The broad band centered at 240 nm was assigned to the charge transfer transition between Eu3+ and the neighboring oxygen anions. The other broad band from 120 nm to 160 nm was attributed to the host absorption, which ensures the efficient absorption of the Xe plasma emission lines. The photoluminescent spectra showed the strongest emission at 614 nm corresponding to the electric dipole 5D0 → 7F2 transition of Eu3+, which resulted in good color purity for display and lamps applications. 相似文献
5.
G.H. Mhlongo M.S. Dhlamini H.C. SwartO.M. Ntwaeaborwa K.T. Hillie 《Optical Materials》2011,33(10):1495-1499
Y2O3:Eu3+ and ZnO·Y2O3:Eu3+ nanophosphor powders with different concentrations of Eu3+ ions were synthesized by a sol-gel method and their luminescence properties were investigated. The red photoluminescence (PL) from Eu3+ ions with the main emission peak at 612 nm was observed to increase with Eu3+ concentration from 0.25 to 0.75 mol% and decreased notably when the concentration was increased to 1 mol%. The decrease in the PL intensity at higher Eu3+ concentrations can be associated with concentration quenching effects. The red emission at 612 nm was shown to increase considerable when ZnO nanoparticles were incorporated in Y2O3:Eu3+ while green emission from ZnO was suppressed. The increase is attributed to energy transfer from ZnO to Eu3+. 相似文献
6.
Zhidong LouMichael Cocivera 《Materials Research Bulletin》2002,37(9):1573-1582
Thin films of CaWO4 and SrWO4 were prepared on glass substrates by spray pyrolysis. The effects of preparation conditions and monovalent, bivalent and trivalent cation doping on cathodoluminescence (CL) properties of the films were studied. Polycrystalline CaWO4 and SrWO4 films formed a scheelite structure after being annealed above 300°C. They exhibited analogous cathodoluminescence consisting of a blue emission band at 447 nm and a blue-green emission band at 487 nm. The blue and blue-green emission intensities increased with substrate and annealing temperature. Annealing atmosphere and doping with Ag+, Pb2+ and La3+ did not influence the characteristics of the blue and blue-green emissions, whereas Eu3+ did. The results indicated both the blue and blue-green emissions originated from the WO42− molecular complex. The luminance and efficiency for CaWO4 film were 150 cd/m2 and 0.7 lm/W at 5 kV and 57 μA/cm2. 相似文献
7.
Xinguo Zhang 《Materials Letters》2009,63(11):852-854
Sr4Si3O8Cl4:Eu2+ and Sr3.5Mg0.5Si3O8Cl4:Eu2+ phosphors were prepared by a conventional solid state reaction (SS). Excited by 370 nm near-ultraviolet light, the phosphors show an efficient bluish-green wide-band emission centering at 484 nm, which originates from the 4f5d1 → 4f7 transition of Eu2+ ion. The excitation spectra of the phosphors are a broad band extending from 250 nm to 400 nm. Mg2+-codoping greatly enhances the bluish-green emission of the phosphors. An LED was fabricated by coating the Sr3.5Mg0.5Si3O8Cl4:0.08Eu2+ phosphor onto an ~ 370 nm-emitting InGaN chip. The LED exhibits bright bluish-green emission under a forward bias of 20 mA. The results indicate that Sr3.5Mg0.5Si3O8Cl4:0.08Eu2+ is a candidate as a bluish-green component for fabrication of NUV-based white LEDs. 相似文献
8.
RMoO4 (RMO, R = Ca, Sr, Ba) films were fabricated on LaAlO3 (LAO) substrates using chemical solution deposition method. The derived RMO films are highly (00l)-orientated with good crystallization. The photoluminescence (PL) emission spectra show that the CaMoO4 (CMO) and SrMoO4 (SMO) films have an intrinsic broad green emission band centered at 500 nm whereas BaMoO4 (BMO) film has a broad orange emission band resulting from the PL of molybdate group with an oxygen ion deficiency. The highly (00l)-oriented CMO film on LAO has better PL property than that of CMO film on Si substrate, which is ascribed to higher crystalline integrity and lower light scattering. 相似文献
9.
A novel blue-emitting Sr3Ga2O5Cl2:Eu2+ phosphor has been synthesized by a two-step solid-state reaction. The luminescence properties have been investigated by photoluminescence (PL) spectra, and temperature-dependent PL spectra. It shows an efficient broad absorption band around 400 nm, which matches well with the commercial near-ultraviolet light-emitting chips, and an efficient blue emission. It shows a higher thermal quenching temperature than that of Sr3Al2O5Cl2:Eu2+ phosphor. Sr3Ga2O5Cl2:Eu2+ phosphor is a promising blue-emitting component for UV chip excited white light-emitting-diodes. 相似文献
10.
The luminescent properties of Na3Y1−xSi3O9:xEu3+ (0.05 ≦ x ≦ 0.80) powder crystals were investigated in UV-VUV region. The Eu3+-O2− charge transfer band (CTB) was observed to be located at around 233 nm and the environmental parameter (he) was estimated to be about 0.730. The excitation spectrum monitoring the 613 nm red emission from Eu3+ ions reveals the host absorption band (HAB) to be around 145 nm. The calculated Commission Internationale de l’Eclairage (CIE) chromaticity coordinates indicate the emission by 233 nm rather than by 147 nm excitation has the better color purity and the possible mechanisms have been proposed. The Eu3+-emission showed high quenching concentration due to the isolated YO6 octahedra in the host and the small he for the Eu3+ ions and the optimum concentration was determined to be as high as x = 0.65 and 0.30 with 233 and 147 nm excitation, respectively. 相似文献
11.
Deok Su JoYuanYuan Luo Karuppanan SenthilKenji Toda Bong Sung KimTakaki Masaki Dae Ho Yoon 《Optical Materials》2012,34(4):696-699
A new NaAlSiO4:0.1Eu2+ phosphors were synthesized at different temperatures using a liquid phase precursor (LPP) technique. The XRD patterns indicate the presence of hexagonal nepheline phase for all the samples. The synthesized phosphors can be excited efficiently in the broad near-UV region. The PL emission spectra showed a broad emission peak at around 551 nm corresponding to 5d → 4f transition of Eu2+ ions. The synthesized phosphors showed better thermal stability when compared with the standard YAG:Ce3+ phosphor. 相似文献
12.
Jinsheng Liao Huazhong Huang Hangying You Xin Qiu Yong Li Bao Qiu He-Rui Wen 《Materials Research Bulletin》2010,45(9):1145-1149
NaGd(MoO4)2:Eu3+ (hereafter NGM:Eu) phosphors have been prepared by sol-gel method. The properties of the resulting phosphors are characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), photoluminescence (PL) spectra and decay curve. The excitation spectra of NGM:Eu phosphors are mainly attributed to O → Mo charge-transfer (CT) band at about 282 nm and some sharp lines of Eu3+ f-f transitions in near-UV and visible regions with two strong peaks at 395 and 465 nm, respectively. Under the 395 and 465 nm excitation, intense red emission peaked at 616 nm corresponding to 5D0 → 7F2 transition of Eu3+ are observed for 35 at.% NGM:Eu phosphors as the optimal doping concentration. The luminescence properties suggest that NGM:Eu phosphor may be regarded as a potential red phosphor candidate for near-UV and blue light-emitting diodes (LEDs). 相似文献
13.
Kyoo Sung Shim Byung Kee Moon Jung Hyun Jeong Jong Soung Bae 《Thin solid films》2009,517(17):5137-6113
Gd-substitution dependency on the photoluminescence in YVO4:Eu3+ films grown on Si (100) substrates have been investigated by analyzing the crystalline phase and surface morphology of the films. The substitution of Gd induced not only the change of crystallinity but also the surface roughness of the films. The change of the preferred orientation in the films can be explained on the basis of the lattice mismatch between the film and Si (100) substrate. Also, the surface roughness of the films shows the similar behavior to the grain size as a function of Gd amounts. The photoluminescence (PL) intensity obtained from the Y1 − xGdxVO4:Eu3+ films grown under optimized conditions have indicated that the PL intensity is more dependent on the surface roughness than the crystallinity of films. In particular, the incorporation of Gd into the YVO4 lattice remarkably enhanced the intensity of PL and the highest emission intensity of Y0.57Gd0.40Eu0.03VO4 film was 3.3 times higher than that of YVO4:Eu3+ film. 相似文献
14.
Yongchao JiaHui Qiao Ning GuoYuhua Zheng Mei YangYeju Huang Hongpeng You 《Optical Materials》2011,33(11):1803-1807
The blue-emitting phosphors Ca(4−x)EuxSi2O7F2 (0 < x ? 0.05) have been prepared by solid-state reaction and the photoluminescence properties have been studied systematically. The electronic structure of calcium fluoride silicate Ca4Si2O7F2 was calculated using the CASTEP code. The calculation results of electronic structure show that Ca4Si2O7F2 has an indirect band gap with 5 eV. The top of the valence band is dominated by O 2p and Si 3p states, while the bottom of the conduction band is mainly composed of Ca 3d states. Under the 350 nm excitation, the obtained sample shows a broad emission band in the wavelength range of 400-500 nm with peaks of 413 nm and 460 nm from two different luminescence centers, respectively. The relative intensity of the two peaks changes with the alteration of the Eu2+ concentration. The strong excitation bands of the powder in the wavelength range of 200-420 nm are favorable properties for the application as lighting-emitting-diode conversion phosphor. 相似文献
15.
Xinghua Zhang Zunming Lu Fanbin MengFang Lu Long HuXuewen Xu Chengchun Tang 《Materials Letters》2012,66(1):16-18
A series of yellow-emitting phosphors based on a silicate host matrix, Ca3 − xSi2O7: xEu2+, was prepared by solid-state reaction method. The structure and photoluminescent properties of the phosphors were investigated. The XRD results show that the Eu2+ substitution of Ca2+ does not change the structure of Ca3Si2O7 host and there is no impurity phase for x < 0.12. The SEM images display that phosphors aggregate obviously and the shape of the phosphor particle is irregular. The EDX results reveal that the phosphors consist of Ca, Si, O, Eu and the concentration of these elements is close to the stoichiometric composition. The Ca3 − xSi2O7: xEu2+ phosphors can be excited at a wavelength of 300-490 nm, which is suitable for the emission band of near ultraviolet or blue light-emitting-diode (LED) chips. The phosphors exhibit a broad emission region from 520 to 650 nm and the emission peak centered at 568 nm. In addition, the shape and the position of the emission peak are not influenced by the Eu2+ concentration and excitation wavelength. The phosphor for x = 0.045 has the strongest excitation and emission intensity, and the Ca3 − xSi2O7: xEu2+ phosphors can be used as candidates for the white LEDs. 相似文献
16.
Li-Ya Zhou Jian-She Wei Ling-Hong Yi Fu-Zhong Gong Jun-Li Huang Wei Wang 《Materials Research Bulletin》2009,44(6):1411-1414
Motivated by the need for new red phosphors for solid-state lighting applications Eu3+-doped MgMoO4 was prepared by solid-state reaction and its excitation and emission spectra were measured at room temperature. In addition, the effects of firing temperature and Eu3+ doping concentration on the PL intensities were also investigated. Compared with Y2O2S:0.05Eu3+, the obtained Mg0.80MoO4:Eu3+0.20 phosphor shows a stronger excitation band near 400 nm and intensely red-emission lines at 616 nm correspond to the forced electric dipole 5D0 → 7F2 transitions on Eu3+ under 394 nm light excitation. The CIE chromaticity coordinates (x = 0.651, y = 0.348) of Mg0.80MoO4:Eu3+0.20 close to the NTSC (National Television Standard Committee) standard values, and therefore may find application on near UV InGaN chip-based white light emitting diodes. 相似文献
17.
Synthesis and luminescence properties of Eu3+ and Tm3+-doped ZnNb2O6 nanocrystals by the sol–gel process were investigated. The products were characterized by differential thermal analysis (DTA), scanning electron microscopy (SEM), and photoluminescence spectroscopy (PL). ZnNb2O6:Eu3+ shows bright red luminescence with maximum peak at 613 nm attributed to 5D0 → 7F2 transition. The major blue emission peak of ZnNb2O6:Tm3+ was at 483 nm, corresponding to the transitions 1G4 → 3H6. The optimum concentration of Eu3+ and Tm3+ showing the maximum PL intensity was 4 mol% and 1 mol%, respectively. 相似文献
18.
BaAl2O4:Eu,Dy (BAO) films have been fabricated on Si substrate by laser ablation, and their fundamental optical property and afterglow characteristics are discussed in comparison with the SrAl2O4:Eu,Dy (SAO) films. The intense green emission near 500 nm that originates from 5d to 4f transition in Eu2+ ions was clearly observed from the BAO films. This photoluminescence peak was at a shorter wavelength than that of the SAO films (λ = 520 nm). The afterglow intensity from the BAO films disappeared within a few minutes whereas that of the SAO films lasts over 20 min. The hole-trap depth (Et) created by Dy as the auxiliary activators, which strongly affects the afterglow characteristics, was estimated on the basis of the thermally stimulated luminescence (TSL) result. The TSL glow curve for BAO films showed two broad peaks at 320 K and 450 K. The calculated Et for each peak was 0.2 eV (for the 320 K peak) and 1.2 eV (for the 450 K peak). On the other hand, Et = 0.5 eV was obtained from the SAO films. The hole-trap depths of the BAO film are either too shallow or too deep to affect the afterglow characteristics at room temperature. 相似文献
19.
Superfine powder SrLu2O4:Eu3+ was synthesized with a precursor prepared by an EDTA - sol-gel method at relatively low temperature using metal nitrate and EDTA as starting materials. The heat decomposition mechanism of the precursor, formation process of SrLu2O4:Eu3+and the properties of the particles were investigated by thermo-gravimetric (TG) - differential thermal analysis (DTA), X-ray diffraction (XRD), transmission electron microscopy (TEM) and photoluminescence (PL) analyses. The results show that pure SrLu2O4:Eu3+ superfine powder has been produced after the precursor was calcinated at 900 °C for 2 h and has an elliptical shape and an average diameter of 80-100 nm. Upon excitation with 250 nm light, all the SrLu2O4:Eu3+ powders show red and orange emissions due to the 4f-4f transitions of Eu3+ ions. The highest photoluminescence intensity at 610 nm was found at a content of about 6 mol% Eu3+. Splitting of the 5D0-7F1 emission transition revealed that the Eu3+ ions occupied two nonequivalent sites in the crystallite by substituting Lu3+ ions. 相似文献
20.
Li Guan Xu Li Guoqi Jia Zhiping Yang Guangsheng Fu 《Materials Research Bulletin》2011,46(9):1496-1499
A series of Eu2+ doped KCaPO4 phosphors were prepared by high temperature solid state reaction and an efficient blue-green emission was observed. The photoluminescence (PL) spectrum of the phosphor appeared one asymmetric peak under near-ultraviolet (n-UV) excitation and two emission bands at 480 nm and 540 nm were obtained using Gaussian fit, which was because Eu2+ ions inhabited two different Ca2+ sites: Eu(I) and Eu(II) in the host lattice, respectively. The excitation spectrum was a broadband extending from 250 to 450 nm, which matched well with the emission of ultraviolet light-emitting diodes (UV LEDs). The effect of Eu2+ concentration on the emission intensity of KCaPO4:Eu2+ phosphor was investigated in detail. 相似文献