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1.
New Ce3+ and/or Mn2+ activated Ca10K(PO4)7 phosphors were prepared by solid-state reaction, and their photoluminescence properties upon ultraviolet and vacuum ultraviolet excitation were investigated. Under 254 nm excitation, a series of Ca10K(PO4)7:xMn2+ samples exhibit two emission bands at 463 and 650 nm, which could be attributed to oxygen defects and 4T1–6A1 transition of Mn2+, respectively. And an energy transfer from defects to Mn2+ has been observed. With the Mn2+ content increased, the emitting hues of Ca10K(PO4)7:Mn2+ can range from blue to red. By co-doping Ce3+ to Ca10K(PO4)7:Mn2+, the emission intensity of Mn2+ is strongly enhanced due to an efficient energy transfer by [Ce3+ → Mn2+] and [defects → Ce3+ → Mn2+]. But under 147 nm excitation, the emission intensity of Mn2+ in Ca10K(PO4)7:0.25Mn2+ decreases slightly compared with that in Ca10K(PO4)7:025Mn2+, 0.1Ce3+, 0.1K+ due to the host sensitization competition between Ce3+ and Mn2+. 相似文献
2.
Aluminium oxide (Al2O3) films doped with CeCl3, TbCl3 and MnCl2 were deposited at 300 °C with the ultrasonic spray pyrolysis technique. The films were analysed using the X-ray diffraction technique and they exhibited a very broad band without any indication of crystallinity, typical of amorphous materials. Sensitization of Tb3+ and Mn2+ ions by Ce3+ ions gives rise to blue, green and red simultaneous emission when the film activated by such ions is excited with UV radiation. The overall efficiency of such energy transfer results to be about 85% upon excitation at 312 nm. Energy transfer from Ce3+ to Tb3+ ions through an electric dipole-quadrupole interaction mechanism appears to be more probable than the electric dipole-dipole one. A strong white light emission for the Al2O3:Ce3+(1.3 at.%):Tb3+(0.2 at.%):Mn2+(0.3 at.%) film under UV excitation is observed. The high efficiency of energy transfer from Ce3+ to Tb3+ and Mn2+ ions, resulting in cold white light emission (x = 0.30 and y = 0.32 chromaticity coordinates) makes the Ce3+, Tb3+ and Mn2+ triply doped Al2O3 film an interesting material for the design of efficient UV pumped phosphors for white light generation. 相似文献
3.
The phosphors in the system Sr2−x−yP2O7:xEu2+,yMn2+ were synthesized by solid-state reactions and their photoluminescence properties were investigated. These phosphors have strong absorption in the near UV region, which is suitable for excitation of ultraviolet light emitting diodes (UVLEDs). The orange-reddish emission of Mn2+ in these phosphors can be used as a red component in the tri-color system and may be enhanced by adjusting the Mn2+/Eu2+ ratio. The energy transfer from Eu2+ to Mn2+ is observed with a transfer efficiency of ∼0.45 and a critical distance of ∼10 Å. The results reveal that Sr2−x−yP2O7:xEu2+,yMn2+ phosphors could be used in white light UVLEDs. 相似文献
4.
Near-infrared (NIR) quantum cutting luminescent materials Li2TeO4 doped with Pr3+ and Yb3+ were synthesized by solid-state reaction method. The dependence of Yb3+ doping concentration on the visible- and NIR-emissions, decay lifetime, and quantum efficiencies of the phosphors are investigated. Quantum cutting down-conversion involving 647 nm red emission and 960-1050 nm broadband near-infrared emission for each 487 nm blue photon absorbed is realized successfully in the resulting phosphors, of which the process of near-infrared quantum cutting could be expressed as 3P0(Pr3+) → 2F5/2(Yb3+) + 2F5/2(Yb3+). The maximum quantum cutting efficiency approaches up to 166.4% in Li2TeO4: 0.3 mol%Pr3+, 1.8 mol%Yb3+ sample corresponding to the 66.4% value of energy transfer efficiency. 相似文献
5.
A novel blue-emitting Sr3Al2O5Cl2:Ce3+,Li+ phosphor has been synthesized by solid state reaction. The excitation spectrum shows a broad band extending from 300 to 400 nm, and the emission spectrum shows a broad blue band peaking at 450 nm with a half width of about 100 nm. The emission intensity at 250 °C remains at about 50% of that at room temperature. The decay curve at the emission peak consists of fast and slow components. The Sr3Al2O5Cl2:Ce3+,Li+ should be a promising blue phosphor for near ultraviolet-based white-light-emitting diodes. 相似文献
6.
A blue-emitting phosphor of NaMg4(PO4)3:Eu2+, Ce3+ was prepared by a combustion-assisted synthesis method. The phase formation was confirmed by X-ray powder diffraction measurement. Photoluminescence excitation spectrum measurements show that the phosphor can be excited by near UV light from 230 to 400 nm and presents a dominant luminescence band centered at 424 nm due to the 4f65d1 → 4f7 transition of Eu2+ ions at room temperature. Effective energy transfer occurs in Ce3+/Eu2+ co-doped NaMg4(PO4)3 due to large spectral overlap between the emission of Ce3+ and excitation of Eu2+. Co-doping of Ce3+ enhances the emission intensity of Eu2+ greatly by transferring its excitation energy to Eu2+, and Ce3+ plays a role as a sensitizer. Ce3+-Eu2+ co-doped NaMg4(PO4)3 powders can possibly be applied as blue phosphors in the fields of lighting and display. 相似文献
7.
Guifang JuYihua Hu Haoyi WuZhongfu Yang Chujun FuZhongfei Mu Fengwen Kang 《Optical Materials》2011,33(8):1297-1301
A series of Eu3+ activated Li6Y1−xEux(BO3)3 (0.05 ? x ? 1) phosphors were synthesized by solid-state reaction method. The structures and photoluminescent properties of the phosphors were investigated at room temperature. The results of XRD patterns indicate that these phosphors are isotypic to the monoclinic Li6Gd(BO3)3. The excitation spectra indicate that these phosphors can be effectively excited by near UV (370-410 nm) light. The red emission from transition 5D0→7F2 is dominant. The emission spectra exhibit strong red performance (CIE chromaticity coordinates: x = 0.65, y = 0.35), which is due to the 5D0−7FJ transitions of Eu3+ ions. The relationship between the structure and the photoluminescent properties of the phosphors was studied. The concentration quenching occurs at x ≈ 0.85 under near UV excitation. Li6Y(BO3)3:Eu3+ has potential application as a phosphor for white light-emitting diodes. 相似文献
8.
Eu2+ and Dy3+ ion co-doped Sr3Al2O6 red-emitting long afterglow phosphor was synthesized by sol-gel-combustion methods using Sr(NO3)2, Al(NO3)3·9H2O, Eu2O3, Dy2O3, H3BO3 and C6H8O7·H2O as raw materials. The crystalline structure of the phosphors were characterized by X-ray diffraction, luminescent properties of phosphors were analyzed by fluorescence spectrophotometer. The effect of excitation wavelengths on the luminescent properties of Sr3Al2O6:Eu2+, Dy3+ phosphors was discussed. The emission peak of Sr3Al2O6:Eu2+, Dy3+ phosphor lays at 516 nm under the excitation of 360 nm, and at 612 nm under the excitation of 468 nm. The results reveal that the Sr3Al2O6:Eu2+, Dy3+ phosphor will emit a yellow-green light upon UV illumination, and a bright red light upon visible light illumination. The emission mechanism was discussed according to the effect of nephelauxetic and crystal field on the 4f65d1 → 4f7 transition of the Eu2+ ions in Sr3Al2O6. The afterglow time of (Sr0.94Eu0.03Dy0.03)3 Al2O6 phosphors lasts for over 600s after the excited source was cut off. 相似文献
9.
Eu3+ doped ZnB2O4 without or with different charge compensation (CC) approaches (co-doping Li+, Na+, K, decreasing the content of Zn2+) were prepared by solid state reactions. The phosphors can strongly absorb 393 nm ultraviolet (UV) light which is coupled well with the emission of currently used InGaN-based near UV light emitting diodes (LEDs) and emit red light with a good color purity. The luminescent intensity of phosphors can be remarkably enhanced with any of CC methods. However, the shape and position of excitation and emission spectra keep unchanged. The introduction of Li+ can enhance the red emission intensity of Eu3+ by ∼4 times with the optimal effect. Red emission of Eu3+ can also be enhanced with the other three CC approaches but the effects are not as good as Li+ because the volume unbalance in Li+ compensation approach is the smallest while net positive charge was offset. The results of this work suggest that volume compensation and equilibrium of mole number should also be taken into account when a CC approaches is selected. 相似文献
10.
Yan Hao 《Materials Research Bulletin》2007,42(12):2219-2223
New phosphors M2(Mg, Zn)Si2O7:Mn2+ (M = Ca, Sr, Ba) were prepared by sol-gel process, and their luminescent properties in ultraviolet and vacuum ultraviolet region were investigated. The results showed that the (Ca, Sr, Ba)2MgSi2O7:Mn2+ samples did not emit any visible light; the Sr2ZnSi2O7:Mn2+ and Ca2ZnSi2O7:Mn2+ samples showed green light. The Ba2ZnSi2O7:Mn2+ sample mainly showed green light under 254 nm excitation and red light under 147 nm excitation. The different emission was due to the Mn2+ ions occupied different sites, which were excited selectively. Among the three phosphors Sr2ZnSi2O7:Mn2+ showed the highest green emission intensity, and its decay time was shorter than that of Zn2SiO4:Mn2+ under 147 nm excitation. 相似文献
11.
Hongbin Liang Zifeng TianHuihong Lin Mubiao XieGuobin Zhang Pieter DorenbosQiang Su 《Optical Materials》2011,33(4):618-622
The spectroscopic properties of Na3Gd(PO4)2 and Na3Gd(PO4)2:Ce3+ phosphors in the VUV-UV spectral range were investigated. Five excitation bands of Ce3+ ions at Gd3+ sites are observed at wavelengths of 205, 246, 260, 292, and 321 nm. Doublet Ce3+ 5d → 4f emission bands are observed at 341 and 365 nm with a decay constant τ1/e around 26 ns. The X-ray excited luminescence of Na3Gd0.99Ce0.01(PO4)2 at room temperature shows a photon yield of ∼17,000 photons/MeV of absorbed X-ray energy. 相似文献
12.
Yu GongYuhua Wang Xuhui XuYanqin Li Shuangyu XinLiurong Shi 《Optical Materials》2011,33(11):1781-1785
Eu2+, Mn2+ and Dy3+ co-doped long-lasting phosphors Sr3MgSi2O8 were prepared by a solid-state reaction under a reductive atmosphere. Fluorescence spectra demonstrated that the weak red emission resulting from the forbidden transition of Mn2+ could be enhanced by the energy transfer from Eu2+ to Mn2+. The energy transfer between Eu2+ and Mn2+ was systematically investigated. The phosphorescence spectra revealed that Eu2+ could persistently transfer its energy to Mn2+ after removing the excitation source. The duration of Mn2+ can prolong to more than 2 h. The thermoluminescence spectra were used to characterize the ability of the trap to trapping the carriers. By the analysis of the ionization potentials, the roles of Mn2+ and Dy3+ in the afterglow process were discussed. A possible afterglow mechanism was presented and discussed. 相似文献
13.
《Materials Research Bulletin》2013,48(11):4749-4753
A series of single-phased emission tunable NaBa4(BO3)3:Ce3+, Tb3+ phosphors were synthesized by solid-state reaction. The crystal structure, photoluminescence properties, concentration quenching and energy transfer of NaBa4(BO3)3:Ce3+, Tb3+ were systematically investigated. The wavelength-tunable bluish-green light can be realized by coupling the emission bands centered at 425 and 543 nm ascribed to the contribution from Ce3+ and Tb3+, respectively. The energy transfer from Ce3+ to Tb3+ in NaBa4(BO3)3 host was studied and demonstrated to be a resonant type via a dipole–dipole interaction mechanism. The energy transfer efficiency (Ce3+ → Tb3+) obtained by decay curves was consistent with the result calculated by the emission intensity, which gradually increased from 0% to 84.5% by increasing the Tb3+ doping content from 0 to 0.45. The results indicate that the NaBa4(BO3)3:Ce3+, Tb3+ phosphors have potential applications as an ultraviolet-convertible phosphor due to its effective excitation in the ultraviolet rang. 相似文献
14.
The present investigation aims to demonstrate the potentiality of Tb3+ and Ce3+ co-doped Ca4Y6(SiO4)6O phosphors. By incorporation of Ce3+ into Ca4Y6(SiO4)6O: Tb3+, the excitation band was extended from short-ultraviolet to near-ultraviolet region. The energy transfer from Ce3+ to Tb3+ in Ca4Y6(SiO4)6O host was investigated and demonstrated to be a resonant type via a dipole–dipole mechanism with the critical distance of 10.2 Å. When excited by 352 nm, Ca4Y6(SiO4)6O: Ce3+, Tb3+ exhibited a brighter and broader violet-blue emission (421 nm) from the Ce3+ and an intense green emission (542 nm) from the Tb3+. Combining the two emissions whose intensities were adjusted by changing the doping levels of the co-activator, an optimized white light with chromaticity coordinates of (0.278, 0.353) is generated in Ca4Y6(SiO4)6O: 2% Ce3+, 8% Tb3+, and this phosphor could be potentially used in near-ultraviolet light-emitting diodes. 相似文献
15.
Jiuping Zhong Chunmeng LiuHongbin Liang Qiang SuJianying Zhou Jiyang Wang 《Optical Materials》2011,34(1):152-154
To improve the infrared emission of Yb3+ ions doped in the garnet host Y3Al5O12 (YAG) single crystal through the energy transfer from Ce3+ to Yb3+ ions, the 〈1 1 1〉-oriented YAG:Ce3+, YAG:Yb3+, YAG:(Ce3+, Yb3+) and Yb3Al5O12:Ce3+ (YbAG:Ce3+) single crystals were grown using the Czochralski Method, respectively. The excitation and emission spectra of these garnet single crystals were characterized. In YAG:Ce3+ crystal, the yellow emission of Ce3+ ions present, but it was completely extinguished in YAG:(Ce3+, Yb3+) crystal and YbAG:Ce3+ crystal. However, the characteristic absorption bands of Ce3+ still existed in the excitation spectrum of Yb3+ ions, which showed that the energy absorbed by Ce3+ ions can be transferred to Yb3+ ions for its infrared emission. 相似文献
16.
Sr3Bi(PO4)3:Eu2+, Sr3Bi(PO4)3:Mn2+, and Sr3Bi(PO4)3:Eu2+, Mn2+ phosphors were synthesized by solid state reaction. The structure and luminescent characteristics were investigated by X-ray powder diffraction and fluorescent spectrophotometer. All samples have the structural type of eulytine. The excitation and emission spectra of Sr3Bi(PO4)3:0.01Eu2+ sample show characteristic bands of Eu2+ ions. Also, the excitation and emission spectra of Sr3Bi(PO4)3:0.06Mn2+ sample show characteristic bands of Mn2+ ions. The emission color of Sr3Bi(PO4)3:Eu2+, Mn2+ sample could be tuned through tuning the co-dopant concentration of Mn2+ ions. The decay times for the Eu2+ ions decrease with the increase of Mn2+ dopant concentration, but the energy transfer efficiency increases with the increase of Mn2+ dopant concentration. On the basis of the luminescent spectra and fluorescence decay curves, we confirm that the energy transfer process from the Eu2+ to Mn2+ ions takes place in the co-doped Sr3Bi(PO4)3 phosphor. Sr3Bi(PO4)3:Eu2+, Mn2+ sample shows the good thermostability. The emission intensity of the sample at 400 K is about 60% of the value at 300 K. These results show Sr3Bi(PO4)3:Eu2+, Mn2+ phosphors could be anticipated for UV-pumped white-light-emitting diodes. 相似文献
17.
YVO4 single crystals doped with Ce3+, Er3+ and Yb3+ ions were grown by the Czochralsski technology. The luminescence properties of Er3+/Yb3+:YVO4 single crystals with different concentration of Ce3+ were studied, and the energy transfer mechanism between Er3+, Yb3+ and Ce3+ was discussed based on their energy level properties. The branching ratios of the 4I11/2 → 4I13/2 transition in different samples were calculated. The results indicate that codopants of Ce3+ greatly enhance the population rate of the 4I13/2 level due to the fast resonant energy transfer between Er3+ and Ce3+, i.e., 4I11/2(Er3+) + 2F7/2(Ce3+) → 4I13/2(Er3+) + 2F5/2(Ce3+). 相似文献
18.
Guanghuan Li Mengmeng Li Linlin Li Hong Yu Haifeng Zou Lianchun Zou Shucai Gan Xuechun Xu 《Materials Letters》2011,65(23-24):3418-3420
The Sr2Al2SiO7:Eu2+, Ce3+ phosphors were synthesized by a high temperature solid-state reaction. Effective energy transfer occurs in Ce3+ and Eu2+ co-doped Sr2Al2SiO7 due to large spectral overlap between the emission of Ce3+ and excitation of Eu2+ ions. Co-doping of Ce3+ enhances the emission intensity of Eu2+ greatly by transferring its excitation energy to Eu2+ ions. The critical distance has been estimated to be about 1.83 nm by spectral overlap method. Furthermore, the developed phosphors can generate lights from blue to green region under the excitation of UV radiation by appropriately tuning the activator content. The Sr2Al2SiO7:Eu2+,Ce3+ phosphors are promising phosphors for warm-white-light-emitting diode because of its effective excitation in the near ultraviolet range. 相似文献
19.
Novel Tb3+ and Mn2+ activated Ca8MgGd(PO4)7 phosphors were synthesized by solid-state reaction and their photoluminescence properties in vacuum ultraviolet region were investigated for the first time. It can be observed from the excitation spectra that the host-related absorption band is located around 170 nm, and it overlaps the O2− → Tb3+ charge transfer band of Ca8MgGd(PO4)7:Tb3+ around 161 nm and the 3d5 → 3d44s transition band of Ca8MgGd(PO4)7:Mn2+ near 200 nm. The 4f-4f 5d spin-allowed and spin-forbidden transitions of Tb3+ are verified to be located at 170-250 and 257-271 nm, respectively. Upon 147 nm excitation, the dominant emission peak intensity of the Ca8MgGd0.1(PO4)7:0.9Tb3+ phosphor is about 2.7 times stronger than that of the commercial Zn2SiO4:Mn2+ green phosphor, and the brightness of the former with a short decay time of 2.5 ms is about 98% of the latter’s. The Ca8MgGd(PO4):Mn2+ phosphor excited at 147 nm exhibits a deep red emission around 650 nm, which could be attributed to the 4T1 → 6A1 transition of Mn2+, with the CIE index (0.679, 0.321). In a word, the results above indicate that both Tb3+ and Mn2+ activated Ca8MgGd(PO4)7 phosphors could be promising for PDP or Hg-free lamp applications. 相似文献
20.
The Ce3+ and Tb3+ co-doped Ln2Si2O7 (Ln = Y, Gd) samples were prepared by sol-gel method. Structure characterization of the phosphor was carried out by X-ray diffraction. The luminescence properties of samples were analyzed by measuring the excitation and emission spectra. It was observed that excitation energy can transfer mutually between Ce3+ and Tb3+ in GPS: Ce3+, Tb3+ samples, while in Y2Si2O7 :Ce3+, Tb3+ samples the energy transfer only progresses from Ce3+ to Tb3+. Based on the energy level diagrams of respective Ce3+, Tb3+ and Gd3+ ion, the detailed pathways for energy transfer are explained. 相似文献