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1.
The upconversion luminescence spectral intensity of Er 3+ in Er 3+ and Yb 3+ codoped ZnO nanocrystals with and without Li + are investigated. Yb 3+ ions as a tradition sensibilizer have efficient energy transfer processes from Yb 3+ ( 2F 5/2) to Er 3+ ( 4I 13/2, 4I 11/2, 4F 9/2), which lead to the increment of upconversion luminescence intensity. Following by adding Li + to the Er 3+ and Yb 3+ codoped ZnO nanocrystals, the upconversion intensity emitted by Er 3+ ions is found greatly enhanced. The enhancement is attributed to the distortion of the local field symmetry of Er 3+ ions, so increases various intra-4f transitions of Er 3+ ions. Both Yb 3+ and Li + can disperse Er 3+ ions in specimen, so reduced the interaction between neighboring Er 3+ ions. 相似文献
2.
Yb 3+ and Er 3+ co-doped YAB powders were prepared by sol-gel method. The structure and fluorescence properties were investigated. XRD pattern indicated that the single phase was obtained at 1150°C and the structure belonged to rhombohedral. Under 379 nm excitation, two emissions around 983 nm and 1531 nm were observed and the effect of Yb 3+ ion concentration on the emission intensity was discussed. The energy transfer was observed under 930 nm excitation and the energy transfer efficiencies for all samples were calculated. The lifetimes of 2 F 5/2 level of Yb 3+ ion and 4 I 13/2 level of Er 3+ ion were measured and the effect of Yb 3+ ion concentration on the lifetime was also discussed. The results indicated that there was an additional mechanism for the decay of 4 I 13/2 level in powder samples. The Yb 3+ and Er 3+ co-doped YAB powders should be a potential candidate for ceramic laser materials. 相似文献
3.
The ZrO 2:Er 3+ codoped with Yb 3+ phosphor powders have been prepared by the urea combustion route. Formation of the compounds ZrO 2:Er 3+ and ZrO 2:Er 3+, Yb 3+ was confirmed by XRD. The frequency upconversion emissions in the green and red regions upon excitation with a CW diode laser at ~978 nm are reported. Codoping with Yb 3+ enhances the emission intensities of the triply ionized erbium in the green and red spectral regions by about ~130 and ~820 times respectively. The emission properties of the ZrO 2:Er 3+ phosphor powders are discussed on the basis of excited state absorption, energy transfer, and cross-relaxation energy transfer mechanisms. 相似文献
4.
高温熔制Er 3+,Yb 3+离子掺杂CaO-Y 2O 3-Al 2O 3-SiO 2系统玻璃,并进行微晶化处理,研究了微晶玻璃中Er 3+离子的发光及上转换发光特性,分析了微晶玻璃上转换发光机理.结果表明:原始玻璃经热处理得到了Er,Yb:YAG微晶玻璃,微晶玻璃中Er 3+离子在室温下 4I 13/2→ 4I 15/2跃迁产生横盖1450—1650nm区间的超宽带荧光,荧光半高宽达180nm,这可能由于YAG微晶相中Er 3+离子与玻璃相中残留Er 3+离子的共同发光;Er 3+与Yb 3+离子局域基质声子能量的降低使微晶玻璃Er 3+离子上转换发光强度与原始玻璃相比显著提高,绿光、红光上转换荧光强度比玻璃样品分别增强约7和3倍;微晶化后Er 3+,Yb 3+离子局域环境发生变化也导致微晶玻璃中Er 3+离子绿光、红光上转换发光相对强度发生变化.
关键词:
铒
镱:钇铝石榴石
微晶玻璃
荧光光谱 相似文献
5.
We have prepared Er 3+/Yb 3+ co-doped transparent phosphate glass ceramics by the high-temperature melting technique, and demonstrated the influence of energy acceptors Ce 3+ ions on the up-conversion and 1.54 μm emission properties of Er 3+. The energy transfer mechanism is discussed based on the energy matching and the energy level structure. The phonon-assisted energy transfer between Er 3+ and Ce 3+ favors population feeding from the 4I11/2 to the 4I13/2 level, and therefore drastically decreases the up-conversion emission intensity of Er 3+. Meanwhile, 1.54 μm fluorescence enhances greatly with the introduction of Ce 3+ ions at the proper concentration. 相似文献
6.
Transparent phosphate glass ceramics co-doped with Er 3+ and Yb 3+ in the system P 2O 5Li 2OCaF 2TiO 2 were successfully synthesized by melt-quenching and subsequent heating. Formation of the nanocrystals was confirmed by X-ray powder diffraction. Judd–Ofelt analyses of Er 3+ ions in the precursor glasses and glass ceramics were performed to evaluate the intensity parameters Ω2,4,6. Under 975 nm excitation, intense upconversion (UC) and infrared emission (1545 nm) were observed in the glass ceramics by efficient energy transfer from Yb 3+ to Er 3+. The luminescence processes were explained and the emission cross section was calculated by Fuchtbauer–Ladenburg (F–L) formula. The results confirm the potential applications of Er 3+/Yb 3+ co-doped glass ceramics as laser and fiber amplifier media. 相似文献
7.
Up-conversion luminescence and energy transfer (ET) processes in Nd 3+-Yb 3+-Er 3+ triply doped TeO 2-ZnO-Na 2O glasses have been studied under 800 nm excitation. Intense green up-conversion emissions around 549 nm, which can be attributed to the Er 3+: 4S 3/2→ 4I 15/2 transition, are observed in triply doped samples. In contrast, the green emissions are hardly observed in Er 3+ singly doped and Er 3+-Yb 3+ codoped samples under the same condition. Up-conversion luminescence intensity exhibits dependence of Yb 2O 3-concentration and Nd 2O 3-concentration. Up-conversion mechanism in the triply doped glasses under 800 nm pump is discussed by analyzing the ET among Nd 3+, Yb 3+ and Er 3+. And a possible up-conversion mechanism based on sequential ET from Nd 3+ to Er 3+ through Yb 3+ is proposed for green and red up-conversion emission processes. 相似文献
8.
Sensitization of the fluorescence of Er3+ in fluoride phosphate glass containing up to 20 mol% phosphates by codoping with Cr3+ and Yb3+ is shown. The low order of ligand field strength for Cr3+ (Dq/B=2.04) results in broad Cr3+ fluorescence overlapping the Yb3+ absorption. The electronic energy transfer efficiency approaches 100%. Deviations of donor decay from the Förster law are interpreted in terms of the inhomogeneously acceptor distribution. The electronic energy transfer efficiency of Yb3+ → Er3+ reaches a maximum value of 75% for glasses containing 20 mol% phosphates. The transfer is shown to be migrationally accelerated by means of GAF-LAF-FB theory. From Judd-Ofelt parameters a stimulated emission cross-section for the transition4I13/2 →4I15/2 of Er3+ of 6.2×10−20 cm2 is derived. The c.w. laser action of Er3+ by Cr3+ excitation and double-step energy transfer is shown. The output is tuned continuously from 1536 to 1596 nm. Flashlamp pumping is also shown. 相似文献
9.
The Yb 3+ to Er 3+ energy transfer in yttrium aluminum borate (YAB) crystal is investigated with the rate equation without considering the back energy transfer. The energy transfer coefficients ( W25) in the crystals with different Yb 3+ concentrations are determined and compared with those in other crystals. The transfer efficiencies and the micro-parameters of energy transfer and migration are also determined. The results show that the energy transfer from Yb 3+ to Er 3+ in YAB crystal is very efficient and the Yb 3+–Er 3+ co-doped YAB crystal may be a good candidate for the 1.55 μm laser media. 相似文献
10.
GdVO 4 single crystal co-doped with Yb 3+ and Er 3+ was grown by the Czochralski method. The X-ray powder diffraction pattern of Yb,Er:GdVO 4 crystal confirms that the as-grown crystal is isostructural with pure GdVO 4 crystal. Its polarized absorption spectra and non-polarized fluorescence spectra were measured at room temperature. The absorption band at 984 nm for π-polarization has an FWHM of about 36 nm, which is favorable for InGaAs LD laser pumping. The spectrum properties of Er 3+ in Yb,Er:GdVO 4 crystal were investigated based on Judd–Ofelt theory. There is strong energy transfer from Yb 3+ to Er 3+ in this crystal. When excited with 980 nm radiation, this crystal emitted strong fluorescence at about 1529 nm and 552.5 nm. The total energy transfer rate and efficiency from Yb 3+ to Er 3+ is 3.33 ms -1 and 67%, respectively. The energy transfer between Er 3+ and Yb 3+ ions is a multistep transfer process, and was investigated based on a random-walk model. The investigation result shows that there is strong cooperative-sensitization effect from Yb 3+ to Er 3+, which is the main upconversion energy-transfer process in this crystal. PACS 42.70.Hj; 81.10.Fq; 42.55.Rz 相似文献
11.
Variations of fluorescence intensity ratio of green (generated from Er 3+ 2H 11/2 and 4S 3/2 levels) and red (generated from the sublevels of Er 3+ 4F 9/2 level) upconversion emissions in Er 3+/Yb 3+/Li +:ZrO 2 nanocrystals have been studied as a function of temperature under 976 nm laser diode excitation. In the temperature range of 323-673 K, the maximum sensitivities of about 0.0134 K − 1 and 0.0104 K − 1 are obtained by using green and red emission, respectively. Er 3+/Yb 3+/Li +:ZrO 2 nanocrystals show potential application value in nanoscale thermal sensor. 相似文献
12.
The energy transfer dynamics between Yb 3+ and Er 3+ ions in lithium niobate is investigated after ytterbium-pulsed excitation at 920 nm. The sensitisation of the LiNbO 3:Er 3+ system with Yb 3+ ions does not modify the lifetime of the 4I 13/2 erbium level (1.5-μm emission), whereas it induces a marked, concentration-dependent change in the lifetime of the 2F 5/2 (Yb 3+) and 4S 3/2 (Er 3+) multiplets (1060-nm and 550-nm emissions, respectively). The results are analysed by using the rate-equation formalism and
cross-relaxation model for the energy transfer.
Received: 15 October 1998 / Revised version: 24 November 1998 / Published online: 24 February 1999 相似文献
13.
Color controllable Er 3+/Yb 3+‐codoped La 2MoO 6 upconverting nanocrystals are successfully synthesized via a facile sol‐gel method. Under the irradiation of 980 nm light, the entire samples exhibit dazzling upconversion (UC) emissions arising from the intra‐4f transitions of Er 3+ ions and the UC emission intensity is strongly dependent on the Yb 3+ ion concentration. Moreover, by controlling the Yb 3+ ion concentration, the emission color is changed from green to yellow and finally to red as a result of the energy back transfer from Er 3+ to Yb 3+ ions, which is further verified by the theoretically discussion based on the steady‐state rate expressions. The optical thermometric properties of the prepared nanocrystals based on the ( 2H 11/2, 4S 3/2) thermally coupled levels of Er 3+ ions are systematically studied by analyzing the temperature‐dependent green UC emission spectra in the range of 303–663 K. The maximum sensor sensitivity of resultant nanocrystals is determined to be 0.0083 K −1 at 510 K. Furthermore, the emitting color of the synthesized nanocrystals relies on the temperature. In addition, the heating effect induced by the excitation pump power is also investigated and the host lattice temperature is enhanced from 319 to 404 K with raising the pump power from 159 to 757 mW. 相似文献
14.
LaF 3:Yb 3+,Er 3+/LaF 3 core/shell nanocrystals were successfully synthesized using solvothermal method. The crystal structure, morphology and photoluminescence properties of as-prepared nanocrystals were investigated in detail. XRD patterns show that the obtained LaF 3:Yb 3+,Er 3+ core and LaF 3:Yb 3+,Er 3+/LaF 3 core/shell nanocrystals exhibit hexagonal structure. The average particle size is about 9.3 nm and 11.4 nm for core and core/shell nanocrystals, respectively. Compared with LaF 3:Yb 3+,Er 3+ nanocrystals, both the upconversion emission intensity and the lifetime increase in LaF 3:Yb 3+,Er 3+/LaF 3 core/shell nanocrystals. The enhancement can be attributed to the LaF 3 shell which can eliminate the nonradiative centers on the surface of LaF 3:Yb 3+,Er 3+ nanocrystals. 相似文献
16.
We prepared Er 3+ doped and Er 3+/Yb 3+ codoped Sb 2O 4 nanocrystals by the sol-gel method. The Raman, X-ray diffraction (XRD), transmission electron microscope (TEM), and photoluminescence spectra of the samples were studied. The phonon energy of the Sb 2O 4 nanocrystals is very low (the maximum value being 461 cm −1). The upconversion (UC) red emission of the Er 3+/Yb 3+ codoped sample is very strong at 975 nm laser diode excitation. The Sb 2O 4 nanocrystals will be a promising luminous material. 相似文献
17.
Energy transfer has been studied from Er 3+ to Eu 3+ ions on excitation with NIR photons (796 and 980 nm) with and without Yb 3+ ions. It is found that in one case the presence of Yb 3+ enhances the fluorescence yield (980 nm excitation) whereas in the other case it quenches (796 nm excitation). Energy transfer from Er 3+ ion's levels 4S 3/2 and 2H 11/2 is verified by decay curve analysis in both the cases. The nature of interaction between the donor (Er) and the acceptor (Eu) ions is found to be dipole-dipole. The energy transfer parameters viz. transfer probability, critical distance etc. have been calculated. 相似文献
18.
采用固相反应方法,制备了Er 2O 3浓度固定为0.5mol%,Yb 2O 3浓度范围为0.0mol%—5.5mol%的Er/Yb共掺激光玻璃.通过吸收光谱、光致荧光光谱和上转换荧光光谱,研究了Yb 2O 3浓度对Er 3+荧光特性的影响,并探讨了相关的物理机制.研究结果表明:Yb 3+共掺对Er 3+的 4
关键词:
Er/Yb共掺
光致荧光
能量传递
合作上转换 相似文献
19.
Er 3+ doped TiO 2–La 2O 3 glasses modified by ZrO 2 have been successfully fabricated by the containerless method with incorporated Yb 3+ ions as sensitizers. Under the excitation of 980 and 808 nm diode lasers, visible emissions centered at 534, 554 and 674 nm are observed, which are assigned to the Er 3+ transitions of 2H 11/2→ 4I 15/2, 4S 3/2→ 4I 15/2 and 4F 9/2→ 4I 15/2, respectively. The emission signals are so strong that they can be observed by naked eyes even at pumping power as low as 20 mW. Measurements of pump-power dependent intensity and time-resolved decay behavior of upconversion luminescence show that two-photon excited state absorption (ESA) and energy transfer (ET) between rare earth ions are the predominant mechanisms for upconversion emissions. Besides, the intensity of upconversion luminescence has been enhanced by increasing the concentration of ZrO 2 in these rare earth doped bulk titanate glasses. 相似文献
20.
Cubic phase Lu 2O 3:Er 3+/Yb 3+ nanocrystal phosphors were prepared by sol–gel method. Fourier transform infrared (FT-IR) spectra were measured to evaluate the vibrational feature of the samples. Green and red radiations were observed upon 980 nm diode laser excitation. Laser power and Er 3+ or Yb 3+ doping concentration dependence of upconversion luminescence were studied to understand upconversion mechanisms. Excited state absorption, cross relaxation and energy transfer processes are the possible mechanisms for the visible emissions. 相似文献
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