共查询到20条相似文献,搜索用时 15 毫秒
1.
Yu. Zorenko V. Gorbenko T. Voznyak T. Zorenko B. Kuklinski R. Turos-Matysyak M. Grinberg 《Optics and Spectroscopy》2009,106(3):365-374
The processes of excitation energy transfer in phosphors based on single-crystal Tb3Al5O12:Ce (TbAG:Ce) and Tb3Al5O12:Ce,Eu (TbAG:Ce,Eu) garnet films have been investigated. These films are considered to be promising materials for screens for X-ray images and luminescence converters of blue LED radiation. The conditions for excitation energy transfer from the matrix (Tb3+ cations) to Ce3+ and Eu3+ ions in TbAG:Ce and TbAG:Ce,Eu phosphors have been analyzed in detail. It is established that a cascade process of excitation energy transfer from Tb3+ ions to Ce3+ and Eu3+ ions and from Ce3+ ions to Eu3+ ions is implemented in TbAG:Ce,Eu via dipole-dipole interaction and through the Tb3+ cation sublattice. 相似文献
2.
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
3.
Calcium lanthanide oxyborate doped with rare-earth ions LnCa4O(BO3)3:RE3+ (LnCOB:RE, Ln=Y, La, Gd, RE=Eu, Tb, Dy, Ce) was synthesized by the method of solid-state reaction at high temperature. Their fluorescent spectra were measured from vacuum ultraviolet (VUV) to visible region at room temperature. Their excitation spectra all have a broadband center at about 188 nm, which is ascribed to host absorption. Using Dorenbos’ and Jφrgensen's work [P. Dorenbos, J. Lumin. 91 (2000) 91, R. Resfeld, C.K. Jφrgensen, Lasers and Excite States of Rare Earth [M], Springer, Berlin, 1977, p. 45], the position of the lowest 5d levels E(Ln,A) and charge transfer band Ect were calculated and compared with their excitation spectra.Eu3+ and Tb3+ ions doped into LnCOB show efficient luminescence under VUV and UV irradiation. In this system, Ce3+ ions do not show efficient luminescence and quench the luminescence of Tb3+ ions when Tb3+ and Ce3+ ions are co-doped into LnCOB. GdCOB doped with Dy3+ shows yellowish white light under irradiation of 254 nm light for the reason that Gd3+ ions transfer the energy from itself to Dy3+. Because of the existence of Gd3+, the samples of GdCOB:RE3+ show higher excitation efficiency than LaCOB:RE3+ and YCOB:RE3+, around 188 nm, which indicates that the Gd3+ ions have an effect on the host absorption and can transfer the excitation energy to the luminescent center such as Tb3+, Dy3+ and Eu3+. 相似文献
4.
Lei Jin Xiaoqing Du Xiaohua Lei Linjiao Ren Yong’an Feng Weimin Chen 《Applied Physics A: Materials Science & Processing》2014,114(2):631-636
Ce, Tb and Eu single and ternary doped borosilicate glasses were prepared and effect of Tb3+ concentration on luminescence properties of ternary co-doped glasses were analyzed by utilizing emission spectra, excitation spectra, the Commission International de I’Eclairage (CIE) colorimetric system and fluorescence decay curves. The results show that Tb3+ concentration significantly affects spectral intensities of ternary co-doped glasses when excited by near ultraviolet (NUV). With the increasing of Tb3+ concentration, the blue emission of Ce3+ is weakened and the red emission of Eu3+ is slightly enhanced. Both the color coordinates and correlated color temperatures (CCTs) can be adjusted by Tb3+ concentration. Besides, the energy transfers from Ce3+ to Tb3+ and from Tb3+ to Eu3+ were observed. Measured characteristic lifetimes of Tb3+ indicate that the energy transfer from Ce3+ to Tb3+ tends to predominate in whole process. The studies show that Ce/Tb/Eu ternary doped borosilicate glasses might be promising luminescence materials for NUV pumped white LEDs. 相似文献
5.
Potential PDP phosphors with strong absorption around 172 nm: Rare earth doped NaLaP2O7 and NaGdP2O7
Jun Lin Yuan Jiao Wang Ding Bang Xiong Jing Tai Zhao Yi Bing Fu Chao Shu Shi 《Journal of luminescence》2007,126(2):717-722
NaLaP2O7 and NaGdP2O7 powder samples are prepared by solid-state reactions at 750 and 600 °C, respectively, and the VUV-excited luminescence properties of Ln3+ (Ln=Ce, Pr, Tb, Tm, Eu) in both diphosphates are studied. Ln3+ ions in both hosts show analogous luminescence. For Ce3+-doped samples, the five Ce3+ 5d levels can be clearly identified. As for Pr3+ and Tb3+-doped samples, strong 4f-5d absorption band around 172 nm is observed, which matches well with Xe-He excimer in plasma display panel (PDP) devices. As a result, Pr3+ can be utilized as sensitizer to absorb 172 nm VUV photon and transfer energy to appropriate activators, and Tb3+-doped NaREP2O7(RE=La, Gd) are potential 172 nm excited green PDP phosphors. For Tm3+ and Eu3+-doped samples, the Tm3+-O2− charge transfer band (CTB) is observed to be at 177 nm, but the CTB of Eu3+ is observed at abnormally low energy position, which might originate from multi-position of Eu3+ ions. The similarity in luminescence properties of Ln3+ in both hosts indicates certain structural resemblance of coordination environment of Ln3+ in the two sodium rare earth diphosphates. 相似文献
6.
Under 254 nm excitation LaMgAl11O19 : Ce3+ shows emission peaking between 340 and 360 nm with a quantum efficiency up to 65%, which is almost independent of the Ce3+ concentration. Energy transfer between the Ce3+ ions is not efficient. In CeMgAl11O19 : Tb3+ efficient energy transfer occurs from Ce3+ to Tb3+, resulting in a green emission with a quantum efficiency up to 65%. The Ce3+ - Tb3+ energy transfer is ascribed to electric dipole-quadrupole interaction. 相似文献
7.
Phosphors CaYBO4:RE3+ (RE=Eu, Gd, Tb, Ce) were synthesized with the method of solid-state reaction at high temperature, and their vacuum ultraviolet (VUV)-visible luminescent properties in VUV-visible region were studied at 20 K. In CaYBO4, it is confirmed that there are two types of lattice sites that can be substituted by rare-earth ions. The host excitation and emission peaks of undoped CaYBO4 are very weak, which locate at about 175 and 350-360 nm, respectively. The existence of Gd3+ can efficiently enhance the utilization of host absorption energy and result in a strong emission line at 314 nm. In CaYBO4, Eu3+ has typical red emission with the strongest peak at 610 nm; Tb3+ shows characteristic green emission, of which the maximum emission peak is located at 542 nm. The charge transfer band of CaYBO4:Eu3+ was observed at 228 nm; the co-doping of Gd3+ and Eu3+ can obviously sensitize the red emission of Eu3+. The fluorescent spectra of CaYBO4:Ce3+ is very weak due to photoionization; the co-addition of Ce3+-Tb3+ can obviously quench the luminescence of Tb3+. 相似文献
8.
Crystal fibers of Ce3+ and Tb3+ singly doped and co-doped CaAl4O7 were grown by the LHPG method. Photoluminescence, excitation spectra and photoconduction were measured. Thermo-stimulated photo-ionization (delocalization) of electrons from the lowest field component of the 5d excited state of Ce3+ was observed in the Ce3+ singly doped sample under excitation at 355 nm. The 5d sublevel was found to locate at 0.3 eV below the conduction band of the host. However, the thermo-stimulated photo-ionization was greatly quenched due to the fast energy transfer from the 5d sublevel to Tb3+ ions in the Ce3+/Tb3+ double doped sample. 相似文献
9.
By using metal nitrates as starting materials, SrAl2B2O7: Tb3+ and SrAl2B2O7: Ce3+, Tb3+ powder phosphors were prepared by sol-gel method. X-ray diffraction (XRD), photoluminescence excitation and emission, as well as kinetic decays were employed to characterize the resulting samples. The results show that energy transfers from Ce3+ to Tb3+ ions. The emission intensity of Tb3+ ions in SrAl2B2O7 could be greatly intensified when Ce3+ ions are doped into SrAl2B2O7: Tb3+. The decay times of SrAl2B2O7: Tb3+ were prolonged when Ce3+ ions were doped. The doping of Ce3+ ions not only improved the luminescent intensity, but also made the materials gets stable luminescent properties. 相似文献
10.
The luminescence of Li2SrSiO4: 0.01Eu, xCe (x=0.0025, 0.005, 0.0075, and 0.01) is studied as a potential ultraviolet light-emitting diode (UV-LED) phosphor that is capable of converting the ultraviolet emission of a UV-LED into white light with good luminosity. There are broad blue and yellow emissions peaked at 413 and 575 nm, respectively. The two emissions come from d-f transitions of Ce3+ and Eu2+, respectively. The emission intensity of Li2SrSiO4: 0.01Eu, xCe reaches its maximum at x=0.0075. The energy transfer from Ce3+ to Eu2+ is demonstrated to be the type of electric dipole-dipole interaction with considerable spectral overlap and nonradiative transition is calculated to dominate. The Commission International de I’Eclairage (CIE) chromaticity coordinates of Ce3+/Eu2+ substituted compounds is also discussed. 相似文献
11.
Borate Ba3InB9O18 (BIBO) has been adopted as a host material for phosphors for the first time. Lanthanide ions (Eu3+/Tb3+)-doped BIBO phosphors have been synthesized by solid-state reaction and luminescent properties investigated under ultravoilet (UV) excitation. For red phosphor BIBO:Eu, dominant emission peaking at 590 nm was attributed to 5D0→7F1 transition of Eu3+, which confirmed that the local site of Eu3+ occupied by In3+ ion in BIBO crystal lattice is at inversion symmetry center. Optimum Eu3+ concentration of BIBO:Eu under UV excitation with 227 nm wavelength is around 40%. The green phosphor BIBO:Tb showed bright green emission at 550 with 232 nm light excited and optimal of Tb3+ concentration measured in BIBO is about 8%. The corresponding luminescence mechanisms of Ln-doped BIBO (Ln=Eu3+/Tb3+) were analyzed. The luminescent intensity of Tb3+ can be significantly improved by co-doping of Bi3+ in the BIBO:Tb lattice. The likely reason was proposed in terms of the different interactions of the host lattice with these ions, and of these ions with each other. 相似文献
12.
Y2O3:Eu3+, Tb3+ phosphors with white emission are prepared with different doping concentration of Eu3+ and Tb3+ ions and synthesizing temperatures from 750 to 950 °C by the co-precipitation method. The resulted phosphors were characterized by X-ray diffraction (XRD) and photoluminescence (PL) spectroscopy. The results of XRD indicate that the crystallinity of the synthesized samples increases with enhancing the firing temperature. The photoluminescence spectra indicate the Eu3+ and Tb3+ co-doped Y2O3 phosphors show five main emission peaks: three at 590, 611 and 629 nm originate from Eu3+ and two at 481 and 541 nm originate from Tb3+, under excitation of 250-320 nm irradition. The white light luminescence color could be changed by varying the excitation wavelength. Different concentrations of Eu3+ and Tb3+ ions were induced into the Y2O3 lattice and the energy transfer from Tb3+→Eu3+ ions in these phosphors was found. The Commission International de l’Eclairage (CIE) chromaticity shows that the Y2O3:Eu3+, Tb3+ phosphors can obtain an intense white emission. 相似文献
13.
Vladimir N. Makhov Cheslav Lushchik Marco Kirm Wei-Ping Zhang Jing-Tai Zhao 《Journal of luminescence》2009,129(12):1711-1714
Luminescence properties of Lu2O3:Eu3+ and Lu2O3:Tb3+ nanocrystalline powders with the particle size varying from 46 to 6 nm were studied under excitation by synchrotron radiation in the photon energy range (up to ∼22.5 eV) covering the region where the processes of multiplication of electronic excitation occur. It was found that the excitation spectra of Tb3+ emission from all Lu2O3:Tb3+ nanopowders have similar behavior, whereas the shape of the excitation spectra of Eu3+ emission from Lu2O3:Eu3+ nanopowders strongly depends on the particle size. The difference in the behavior of Lu2O3:Eu3+ and Lu2O3:Tb3+ nanophosphor systems was explained by different mechanisms of the energy transfer from the host to Eu3+ or Tb3+ ions (either the hole or electron recombination mechanism, respectively), which are differently influenced by losses of electronic excitations near the particle surface. 相似文献
14.
S. Mukherjee 《Journal of luminescence》2009,129(1):69-3743
Yttrium aluminum garnet nanoparticles both undoped and doped with lanthanide ions (Ce3+, Eu3+, Dy3+ and Tb3+) having average size around 30 (±3 nm) nm were prepared by glycine nitrate combustion method followed by annealing at a relatively low temperature of 800 °C. Increase in the annealing temperature has been found to improve the luminescence intensity and for 1200 °C heated samples there exists strong energy transfer from Tb3+ to Ce3+ ions in YAG:Ce(2%),Tb(2%) nanoparticles as revealed by luminescence studies. Co-doping the YAG:Ce nanoparticles with Eu3+ results in significant decrease in the emission intensity of both Ce3+ and Eu3+ ions and this has been attributed to the oxidation of Ce3+ to Ce4+ and reduction of Eu3+ to Eu2+ ions. Dy3+ co-doping did not have any effect on the Ce3+ emission as there is no energy transfer between Dy3+ and Ce3+ ions. 相似文献
15.
The optical properties of Ba1.6Ca0.4P2O7 doped with Ce3+ and Tb3+ are investigated. Under excitation at 280 nm the emission spectrum of Ba1.6Ca0.4P2O7:Ce3+ consists of a peak at 370 nm and a shoulder at the longer wavelength side. The emission spectra of Ba1.6Ca0.4P2O7:Tb3+ shows the well-known emission lines due to 5D4-7FJ transitions of Tb3+. The green emissions of Tb3+ ions are enhanced upon UV excitation through energy transfer from Ce3+ to Tb3+ ions. The efficiency of such an energy transfer is estimated based on spectroscopic data. The dependence of photoluminescence (PL) intensities of Ce3+ and Tb3+ emissions on Ce3+ or Tb3+ concentrations in the systems (Ba1.6Ca0.4P2O7:0.04Ce3+,xTb3+ and Ba1.6Ca0.4P2O7:xCe3+,0.04Tb3+) and the temperature dependence of PL emission spectra of Ba1.6Ca0.4P2O7:0.06Ce3+,0.04Tb3+ is also investigated. 相似文献
16.
Ce3+ and Tb3+ co-doped Sr2B5O9Cl phosphors with intense green emission were prepared by the conventional high-temperature solid-state reaction technique. A broad band centered at about 315 nm was found in phosphor Sr2B5O9Cl: Ce3+, Tb3+ excitation spectrum, which was attributed to the 4f-5d transition of Ce3+. The typical sharp line emissions ranging from 450 to 650 nm were originated from the 5D4 → 7FJ (J = 6, 5, 4, 3) transitions of Tb3+ ions. The photoluminescence (PL) intensity of green emission from Tb3+ was enhanced remarkably by co-doping Ce3+ in the Tb3+ solely doped Sr2B5O9Cl phosphor because of the dipole-dipole mechanism resonant energy transfer from Ce3+ to Tb3+ ions. The energy transfer process was investigated in detail. In light of the energy transfer principles, the optimal composition of phosphor with the maximum green light output was established to be Sr1.64Ce0.08Tb0.1Li0.18B5O9Cl by the appropriate adjustment of dopant concentrations. The PL intensity of Tb3+ in the phosphor was enhanced about 40 times than that of the Tb3+ single doped phosphor under the excitation of their optimal excitation wavelengths. 相似文献
17.
Jianshe Wang Zongwu WangXia Li Si WangHuadan Mao Zhongjun Li 《Applied Surface Science》2011,257(16):7145-7149
The preparation of benzoic acid-functionalized CaF2:Ln3+ (Ln = Eu or Tb) nanoparticles and their sensitized luminescence are described in this report. First, to achieve sufficient proof for energy transfer from benzoic acid (BA) to lanthanide ions doped in nanoparticles, we employ Eu3+ as the microscopic probe and investigate the luminescent spectra of benzoic acid-functionalized CaF2:Eu3+ (BA-CaF2:Eu3+) nanoparticles. Next, to further reveal the difference between sensitized luminescence and common luminescence for Eu3+ doped in CaF2 nanoparticles, we study the emission spectra of BA-CaF2:Eu3+ nanoparticles excited at 286 nm and 397 nm, respectively. Finally, we analyze and compare the luminescent spectra of BA-CaF2:Tb3+ and CaF2:Ce3+, Tb3+ nanoparticles in detail. Our results indicate that both Eu3+ and Tb3+ doped in CaF2 nanoparticles can be efficiently sensitized through benzoic acid. 相似文献
18.
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
19.
Uninuclear europium (Eu), as well as binuclear Eu and terbium (Tb), complexes were synthesized using acrylic acid (AA) as the first ligand and 1,10-phenanthroline (Phen) as the second ligand. The relative weight ratio of the europium (III) (Eu3+) to terbium (III) (Tb3+) ions of the binuclear complex was 1:1 as determined via energy dispersive X-ray analysis. The structures of the Eu(AA)3Phen and Eu0.5Tb0.5(AA)3Phen complexes were characterized by Fourier transform infrared spectroscopy. A series of tri-cellulose acetate (TCA)/ the Eu(AA)3Phen and TCA/Eu0.5Tb0.5(AA)3Phen composites were prepared by solution blending, and their luminescent properties were investigated by fluorescence spectrophotometry. The excitation spectra of all composites indicated that the TCA matrix probably affected the energy absorption and transfer of organic ligands. In TCA/Eu0.5Tb0.5(AA)3Phen composites the introduced Tb3+ ions had some influence on energy absorption and transfer of organic ligands; the energy transfer process of the complex is suggested to be as follows: Phen→AA→Tb3+ion→Eu3+ion. The emission spectra indicated that the luminescent intensity of the TCA/Eu0.5Tb0.5(AA)3Phen composites was noticeably stronger than that of the TCA/Eu(AA)3Phen composites, suggesting that the comparatively stable and high-efficiency energy transfer process was only slightly influenced by the TCA matrix. In summary, the TCA/Eu0.5Tb0.5(AA)3Phen (90/10) composite possesses fine luminescent properties for potential usage as red fluorescent materials. 相似文献
20.
Yttrium aluminum garnet (YAG) particles doped with Tb3+ or double doped with Tb3+ and Ce3+ were prepared by spray pyrolysis and characterized by photo- and cathode-luminescence. It was tried to incorporate a broad band of Ce3+ activator into the line peaks of Tb3+ in YAG host without the reduction of emission intensity. Ce-codoped YAG:Tb particles showed a broad band emission due to the d-f transition of Ce3+ and a reduction in the intensity of emission peaks due to 5D3-7Fj (j=3, 4, 5, 6) transition of Tb3+ when they were excited by the ultraviolet light of 270 nm. These results supported that an effective energy transfer occurs from Tb3+ to Ce3+ in YAG host. Codoping Ce3+ ions greatly intensified the excitation peak at 270 nm for the emission at 540 nm of Tb3+, which means that more lattice defects, involving in the energy absorption and transfer to Tb3+, are formed by the Ce3+ codoping. The finding gives a promising approach for enhancing the luminescence efficiency. 相似文献