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1.
R. Martínez-Martínez A. Speghini M. Bettinelli C. Falcony U. Caldio 《Journal of luminescence》2009,129(11):1276-1280
The photoluminescence of Ce3+, Tb3+ and Mn2+ ions was investigated in the Zn(PO3)2 glass. The blue and green emissions of Tb3+ ions and the red emission of Mn2+ ions are enhanced upon UV excitation through a non-radiative energy transfer from Ce3+ to Tb3+ and Mn2+ ions. The efficiency of this transfer was estimated in at least 62%. It is demonstrated that this glass activated with three ions (Ce3+, Tb3+ and Mn2+) can generate white light emission (x=0.420 and y=0.423 chromaticity coordinates and 3440 K colour temperature) under excitation at 254 nm, i.e., using an AlGaN-based LED as excitation source. 相似文献
2.
Non-radiative energy transfers (ET) from Ce3+ to Pr3+ in Y3Al5O12:Ce3+, Pr3+ and from Sm3+ to Eu3+ in CaMoO4:Sm3+, Eu3+ are studied based on photoluminescence spectroscopy and fluorescence decay patterns. The result indicates an electric dipole-dipole interaction that governs ET in the LED phosphors. For Ce3+ concentration of 0.01 in YAG:Ce3+, Pr3+, the rate constant and critical distance are evaluated to be 4.5×10−36 cm6 s−1 and 0.81 nm, respectively. An increase in the red emission line of Pr3+ relative to the yellow emission band of Ce3+, on increasing Ce3+ concentration is observed. This behavior is attributed to the increase of spectral overlap integrals between Ce3+ emission and Pr3+ excitation due to the fact that the yellow band shifts to the red spectral side with increasing Ce3+ concentration. In CaMoO4:Sm3+, Eu3+, Sm3+-Eu3+ transfer occurs from 4G5/2 of Sm3+ to 5D0 of Eu3+. The rate constant of 8.5×10−40 cm6 s−1 and the critical transfer distance of 0.89 nm are evaluated. 相似文献
3.
The paper is dedicated to investigation of the Mn2+ luminescence in Tb3Al5O12 (TbAG) garnet, as well as the processes of excitation energy transfer between host cations (Tb3+ ions) and activators (Mn2+ and Mn2+-Ce3+ pair ions) in single crystalline films of TbAG:Mn and TbAG:Mn,Ce garnets which can be considered as promising luminescent materials for conversion of LED's radiation. Due to the effective energy transfer between TbAG host and activator, Mn2+ ions in TbAG possess the bright orange luminescence in the bands peaked at 595 nm with a lifetime of 0.64 ms which are caused by the 4T1→6A1 radiative transitions. The simultaneous process of energy transfer is realized in TbAG:Mn,Ce: (i) from Tb3+ to Mn2+ ions; (ii) from Tb3+ cations to Ce3+ ions and then partly to Mn2+ ions through Tb3+ ion sublattice and Ce-Mn dipole-dipole interaction. 相似文献
4.
The spectroscopic properties in UV-excitable range for the phosphors of Sr3La2(BO3)4:RE3+ (RE3+=Eu3+, Ce3+, Tb3+) were investigated. The phosphors were synthesized by conventional solid-state reactions. The photoluminescence (PL) spectra and commission international de I'Eclairage (CIE) coordinates of Sr3La2(BO3)4:RE3+ were investigated. The f-d transitions of Eu3+, Ce3+ and Tb3+ in the host lattices are assumed and corroborated. The PL and PL excitation (PLE) spectra indicate that the main emission wavelength of Sr3La2(BO3)4:Eu3+ is 611 nm, and Sr3La2(BO3)4:Ce3+ shows dominating emission peak at 425 nm, while Sr3La2(BO3)4:Tb3+ displays green emission at 487, 542, 582 and 620 nm. These phosphors were prepared by simple solid-state reaction at 1000 °C. There are lower reactive temperature and more convenient than commercial phosphors. The Sr3La2(BO3)4:Tb3+ applied to cold cathode fluorescent lamp was found to emit green light and have a major peak wavelength at around 542 nm. These phosphors may provide a new kind of luminescent materials under ultraviolet excitation. 相似文献
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Spectroscopic properties and energy transfer (ET) in Ga2O3-GeO2-Bi2O3-Na2O (GGBN, glass doped with Er3+ and rare earths (RE3+; RE3+=Ce3+, Tb3+) have been investigated. Intense 1.53-μm emission with the peak emission cross-section achieved to 7.58×10−21 cm2 from Er3+-doped GGBN glass has been obtained upon excitation at 980 nm. Effects of RE3+ (RE3+=Ce3+, Tb3+) codoping on the optical properties of Er3+-doped GGBN glass have been investigated and the possible ET mechanisms involved have also been discussed. Significant enhancement of the 1.53 μm emission intensity and decrease of upconversion (UC) fluorescence with increasing Ce3+ concentration have been observed. The incorporation of Tb3+ into Er3+-doped GGBN glass could significantly decrease the UC emission intensity, but meanwhile decrease the 1.53 μm emission intensity due to the ET from Er3+:4I13/2 to Tb3+:7F2. The results indicate that the incorporation of Ce3+ into Er3+-doped GGBN glass can effectively improve 1.53-μm and lower UC luminescence, which makes GGBN glass more attractive for use in C-band optical fiber amplifiers. 相似文献
7.
Low temperature quenching and high efficiency CaSc2O4:Ce3+ (CSO:Ce3+) phosphors co-doped with Tm3+, La3+ and Tb3+ ions were prepared by a solid state method and the phase-forming, morphology, luminescence and application properties of these phosphors were investigated. The results showed that co-doping of Tm3+, La3+ and Tb3+ ions can improve the luminescence properties and decrease temperature quenching of CSO:Ce3+ phosphor remarkably. High efficiency green-light-emitting diodes were fabricated with the prepared phosphors and InGaN blue-emitting (∼460 nm) chips. The good performances of the green-light-emitting LEDs made from co-doped CSO:Ce3+ phosphors confirm the luminescence enhancement and indicate that Tm3+, La3+ and Tb3+ co-doped CSO:Ce3+ phosphors are suitable candidates for the fabrication of high efficiency white LEDs. 相似文献
8.
Red-emitting Y2O3:Eu3+ and green-emitting Y2O3:Tb3+ and Y2O3:Eu3+, Tb3+ nanorods were synthesized by hydrothermal method. Their structure and micromorphology have been analyzed by X-ray powder diffraction (XRD) and transmission electron microscopy (TEM). The photoluminescence (PL) property of Y2O3:Eu3+,Tb3+ phosphor was investigated. In the same host (Y2O3), upon excitation with ultraviolet (UV) irradiation, it is shown that there are strong emissions at around 610 and 545 nm corresponding to the forced electric dipole 5D0-7F2 transition of Eu3+ and 5D4-7F5 transition of Tb3+, respectively. Different qualities of Eu3+and Tb3+ ions are induced into the Y2O3 lattice. From the excitation spectrum, we speculate that there exists energy transfer from Tb3+ to Eu3+ ions .The emission color of powders reveals regular change in the separation of light emission. These powders can meet with the request of optical display material for different colors or can be potentially used as labels for biological molecules. 相似文献
9.
Ce3+ and Dy3+ activated Li2CaGeO4 phosphors were prepared by a solid-state reaction method, and characterized by XRD (X-ray diffraction) and photoluminescence techniques. The characteristic emission bands of Dy3+ due to 4F9/2→6H15/2 (blue) and 4F9/2→6H13/2 (yellow) transitions were detected in the emission spectra of Li2CaGeO4:Dy3+. Ce3+ broad band emission was observed in Li2CaGeO4:Ce3+ phosphors at 372 and 400 nm due to 5d→4f transition when excited at 353 nm. Co-doping of Ce3+ enhanced the luminescence of Dy3+ significantly and concentration quenching occurs when Dy3+ is beyond 0.04 mol%. White-light with different hues can be realized by tuning Dy3+ concentration in the phosphors. 相似文献
10.
A series of silica doped with different mol percentages of Ce3+ concentration was synthesized using a sol-gel method to determine the dependence of photoluminescence wavelengths and intensity on the concentrations of the dopants. Sol-gel glasses are porous networks that have been densified through chemical processing and heat treatment. Rare-earths (REs) are insoluble in silica; due to this insolubility RE ions in silicate glasses enter as network modifiers and compete for non-bridging oxygen in order to complete their coordination. The morphological, structural, thermal and optical properties of the phosphors were characterized by X-ray diffraction, scanning electron microscopy, UV-vis absorption, photoluminescence, thermogravimetric analyses and differential scanning calorimeter. Silica (SiO2) gel containing Ce3+ ions was sputter coated with Au (gold) in order to monitor surface morphology of the samples. The highest emission intensity was found for the sample with a composition of 0.5 mol% Ce3+. Cerium doped silica glasses had broad blue emission corresponding to the 2D3/2-2FJ transition at 448 nm but exhibited apparent concentration quenching above concentrations of 0.5 mol% Ce3+. 相似文献
11.
Xiaochen Yu Wentao Wang Lanjun Luo Chengguo Ming Zhenzhou Cheng Lin Han Tongqing Sun Hua Yu Jianguo Tian 《Optics Communications》2009,282(10):2045-123
We have prepared Er3+/Yb3+ co-doped transparent phosphate glass ceramics by the high-temperature melting technique, and demonstrated the influence of energy acceptors Ce3+ ions on the up-conversion and 1.54 μm emission properties of Er3+. The energy transfer mechanism is discussed based on the energy matching and the energy level structure. The phonon-assisted energy transfer between Er3+ and Ce3+ favors population feeding from the 4I11/2 to the 4I13/2 level, and therefore drastically decreases the up-conversion emission intensity of Er3+. Meanwhile, 1.54 μm fluorescence enhances greatly with the introduction of Ce3+ ions at the proper concentration. 相似文献
12.
O.M. Ntwaeaborwa H.C. Swart P.H. Holloway 《Journal of Physics and Chemistry of Solids》2006,67(8):1749-1753
Enhanced green photoluminescence and cathodoluminescence (CL) from Tb3+ ions due to co-doping with Ce3+ ions were observed from SiO2:Ce,Tb powder phosphors prepared by a sol-gel technique. Blue emission from the Ce3+ ions was completely suppressed by Tb co-doping, presumably due to energy transfer from Ce3+ to Tb3+. In addition, the green CL intensity from SiO2:Ce,Tb degraded by ∼50% when the powders were irradiated for 10 h with a 2 keV, 54 mA/cm2 beam of electrons in an ultra-high vacuum chamber containing either 1×10−8 or 1×10−7 Torr O2. Desorption of oxygen from the surface was observed during the decrease of CL intensity. The mechanisms for energy transfer from Ce3+ ions to Tb3+ ions to enhance the green luminescence, and mechanisms for desorption of oxygen from the phosphor surface that would result in decreased CL intensity are discussed. 相似文献
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14.
Tb3+ activated Sr4Al14O25 phosphors were synthesized by the high temperature solid-state reaction. For the sample, the color of the photoluminescence (PL) was green, but that of the afterglow was blue. The spectral results indicated that the photoluminescence was mainly due to the transitions from 5D4 to the ground energy levels of Tb3+ and obeyed the cross-relaxation mechanism; however, the afterglow was derived from the transitions from 5D3 and independent with the concentration of Tb3+. This difference was attributed to the reason that the energy transfer process of cross-relaxation was halted by the traps during the period of afterglow. 相似文献
15.
G. Stryganyuk T. Shalapska A. Voloshinovskii A. Krasnikov 《Journal of luminescence》2011,131(10):2027-2035
Spectral-kinetic characteristics of Gd3+ and Ce3+ luminescence from a series of Ce3+-doped alkali gadolinium phosphates of MGdP4O12 type (M=Li, Na, Cs) have been studied within 4.2-300 K temperature range using time-resolved luminescence spectroscopy techniques. The processes of energy migration along the Gd3+ sub-lattice and energy transfer between the Gd3+ and Ce3+ ions have been investigated. Peculiarities of these processes have been compared for MGdP4O12 phosphate hosts with different alkali metal ions. A contribution of different levels from the 6Pj multiplet of the lowest Gd3+ excited state into the energy migration and transfer processes has been clarified. The phonon-assisted occupation of high-energy 6P5/2, 3/2 levels by Gd3+ in the excited 6Pj state has been revealed as a shift of Gd3+6Pj→8S7/2 emission into the short-wavelength spectral range upon the temperature increase. The relaxation of excited Gd3+ via phonon-assisted population of Gd3+6P5/2 level (next higher one to the lowest excited 6P7/2) is supposed to be responsible for the rise in probability of energy migration within the Gd3+ sub-lattice initiating the Gd3+→Ce3+ energy transfer at T<150 K, whereas further intensification of Gd3+→Ce3+ energy transfer at T>150 K is explained by the increase in probability of Gd3+ relaxation into the highest 6P3/2 level of the 6Pj multiplet. An efficient reversed Ce3+→Gd3+ energy transfer has been revealed for the studied phosphates at 4.2 K. 相似文献
16.
Low thermal quenching and high-efficiency Ca3Sc2Si3O12:Ce3+ (CSSO:Ce3+) phosphors with co-doping Tb3+ ion were prepared by a solid state method and the properties of these phosphors were investigated. The results showed that co-doping of Tb3+ not only enhances the photoluminescence remarkably and decreases the thermal quenching of the phosphor, but also heightens the performances of the LEDs fabricated with the phosphor. A high-efficiency and low color temperature white LED was fabricated with the prepared CSSO:1%Ce3+, 0.5%Tb3+ and a red phosphor, indicating that CSSO:1%Ce3+,0.5%Tb3+ phosphor is a suitable green phosphor for the fabrication of high-efficiency white LEDs. 相似文献
17.
An enhancement in NIR luminescence from Nd3+-doped Ce3+ co-doped SiO2+Al2O3 sol–gel glasses has been observed. The lasing transition (4F3/2→4I11/2) at 1072 nm from the dual rare-earth Nd3++Ce3+-doped glasses has shown an emission strength of about five times that of the single rare-earth ion Nd3+-doped glass. From the measurement of lifetimes of the transition at 1072 nm, the transfer rate (Wtr), critical distance (R0) and energy transfer efficiency (η) of the neodymium glasses have been calculated. 相似文献
18.
A novel strong green phosphor: K3Gd(PO4)2:Ce^3+, Tb^3+ for a UV-excited white light-emitting-diode
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A series of K3Gd1-x-y(PO4)2:xCe^3+, yTb^3+ phosphors are synthesized by the solid-sate reaction method. X-ray diffraction and photoluminescence spectra are utilized to characterize the structures and luminescence properties of the as-synthesized phosphors. Co-doping of Ce^3+ enhances the emission intensity of Tb^3+ greatly through an efficient energy transfer process from Ce^3+ to Tb^3+. The energy transfer is confirmed by photoluminescence spectra and decay time curves analysis. The efficiency and mechanism of energy transfer are investigated carefully. Moreover, due to the non- concentration quenching property of K3Tb(PO4)2, the photoluminescence spectra of K3Tb1-x(PO4)2:xCe^3+ are studied and the results show that when x = 0.11 the strongest Tb^3+ green emission can be realized. 相似文献
19.
L.F. Koao 《Physica B: Condensed Matter》2009,404(22):4499-4503
In this paper, we report enhanced luminescence of Mg-co-doped silica gels, which were prepared by a sol-gel method. The total amount of Ce3+ ions was kept constant in this experiment at 0.5 mol% total doping. Structural, morphological, thermal, optical absorption and photoluminescence studies were employed. The XRD spectra show that all the samples are non-crystalline. Scanning electron microscopy (SEM) images show that the particles were in nano-range and spherical in shape. Differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) of samples depict that the presence of dopant and co-dopant decreases the endothermic peak temperature; while Ce3+ increase the yield, Mg2+ reduces it. UV analyses revealed that the presence of Ce3+ ions increases transmittance but lowers absorbance of annealed silica xerogels, while that of Mg2+ ions reduces transmittance but increases absorbance. Luminescence intensities were compared for different gels with and without Mg particles by varying the different concentrations of Mg. Silica containing Mg2+ ions had broad blue emission due to energy transfer from Mg2+ to Ce3+, which is due to radiative recombination. An increase in luminescence intensity was observed as the Mg2+ to Ce3+ ratio increased for the range investigated. 相似文献
20.
Si-qing Shen Qing Ma Zhi-bin Xu Jian-jun Xie Ying Shi Jian Wang Fei Ai 《Applied Surface Science》2011,258(5):1768
Tb3+-doped lutetium oxyorthosilicate (Tb:Lu2SiO5, LSO) films have been successfully fabricated on carefully cleaned silicon (1 1 1) substrates by Pechini sol–gel method combined with the spin-coating technique. X-ray diffraction (XRD), photoluminescence (PL) spectra and atomic force microscopy (AFM) were employed to characterize the resultant films. XRD patterns indicated that the films were crystallized into A-type LSO phase at 1000 °C, followed by a phase transition from A-type LSO to B-type LSO occurred at 1100 °C. The AFM observation revealed that the phosphor films were uniform and crack-free, consisting of closely packed grains with an average size of 200–300 nm. The PL spectra showed the characteristic emission 5D4 → 7FJ (J = 3–6) for Tb3+, The lifetime of Tb3+ in Tb:LSO films was 2.33 ms. The effect of heat-treatment temperature on the luminescent properties was also investigated. 相似文献