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1.
X. Liu S. Ye Y. Qiao G. Dong B. Zhu D. Chen G. Lakshminarayana J. Qiu 《Applied physics. B, Lasers and optics》2009,96(1):51-55
In the present paper, we investigate the near-infrared (NIR) luminescence of Tb3+–Yb3+ codoped lanthanum borogermanate (LBG) glasses under visible and ultraviolet light excitation. The results indicate that NIR
quantum cutting occurs through cooperative energy transfer from Tb3+ to Yb3+ ions when only 4f
8 levels of Tb3+ ions are excited in the wavelength region of 300–490 nm. The highest quantum efficiency under the excitation 5
D
4 level of Tb3+ at 484 nm is 146%. Ultraviolet excitation that populates the charge transfer band (CTB) of Yb3+ near 270 nm does not result in quantum cutting as the fast nonradiative decay from CTB to 2
F
5/2 level dominates. These materials are expected to be used as a converting layer for silicon solar cells to enhance their efficiency
by splitting each high-energy photon into two NIR photons. 相似文献
2.
YbF3 particles doped with Ho3+ were synthesized by coprecipitation method, from which the ultraviolet and visible emission bands of the Ho3+ and the 480 nm cooperative upconversion emission of Yb3+–Yb3+ are observed under 980 nm excitation. Under the same excitation power, the emission intensity of Ho3+ in coprecipitation method is enhanced by about two times comparing to that in solid-state reaction method. The novel ultraviolet
and violet emissions of the Ho3+ are firstly obtained which are centered at 360 (5G2→5I8),391 (3K7→5I8),412 (5G4→5I8), and 446 nm (5G5→5I8). The luminescence decay profiles of 545 and 652 nm visible emissions were obtained with a 980 nm pulsed laser. The excitation
power dependence of the emission intensity was also measured and intensity saturation was observed. Based on the level structures
of Ho3+, two- and three-photon processes are suggested to perform populations of 5S2 and 5G3 (Ho3+) levels, respectively. The dominant upconversion mechanism may be attributed to a cooperative sensitization process of two
excited states of Yb3+ and energy transfers from Yb3+ to Ho3+. 相似文献
3.
Xvsheng Qiao Xianping Fan Zheng Xue Xuanhe Xu Qun Luo 《Journal of luminescence》2011,131(10):2036-2041
The preparation and upconversion luminescence properties of the Yb3+ and Tb3+ co-doped glass ceramics containing SrF2 nanocrystals were investigated. The formation of SrF2 nanocrystals was confirmed by X-ray diffraction and transmission electron microscopy. Both microstructural and spectral analysis indicated that the Yb3+ and Tb3+ ions were enriched in the precipitated SrF2 nanocrystals, which provide much lower phonon vibration energy than the glass matrix. Due to the efficient cooperative sensitization from Yb3+ to Tb3+ and the relatively low maximum phonon energy of SrF2 nanocrystals, the Yb3+ and Tb3+ co-doped glass ceramics exhibited intense upconversion luminescence, including ultraviolet emission at 382 nm. 相似文献
4.
通过燃烧法制备了Yb3+-Tm3+共掺的Y2O3纳米粉体,并对样品在980 nm激光照射下的上转换发光特性进行了研究.实验发现,样品在可见光区域能够产生强烈的蓝色发光(476 nm和487 nm)和较弱的红色发光(约650 nm),而且同时观察到了两个紫外发光峰1I6→3H6 (~297 nm)和1
关键词:
2O3:Yb3+')" href="#">Y2O3:Yb3+
3+')" href="#">Tm3+
上转换光谱
敏化
紫外发光 相似文献
5.
Yb3+ doped phosphor of Gd2O3 (Gd2O3:Yb3+) have been prepared by solid state reaction method. The structure and the particle size have been determined by X-ray powder diffraction measurements. The average particle size of the phosphor is in between 35 and 50 nm. The particle size and structure of the phosphor was further confirmed by TEM analysis. The visible and NIR luminescence spectra were recorded under the 980 nm laser excitation. The visible upconversion luminescence of Yb3+ ion was due to cooperative luminescence and the presence of rare earth impurity ions. The cooperative upconversion and NIR luminescence spectra as a function of Yb3+ ion concentration were measured and the emission intensity variation with Yb3+ ion concentration was discussed. Yb3+ energy migration quenched the cooperative luminescence of Gd2O3:Yb3+ phosphor with doping level over 5%, while the NIR emission luminescence continuously increases with increasing Yb3+ ion concentration. 相似文献
6.
Polycrystalline GdAl3(BO3)4 phosphors codoped with Yb3+/Tb3+ and/or Nd3+/Yb3+/Tb3+ have been synthesized by combustion method. Upon excitation with a 980 nm laser diode, an intense green upconversion luminescence
has been observed in GdAl3(BO3)4:Yb,Tb phosphor. The quadratic dependence of the luminescence on the pump-laser power indicating a cooperative energy transfer
process. Meanwhile, it is noticed that upon excitation with 808 nm laser diode, intense luminescence has clearly been detected
in GdAl3(BO3)4:Nd,Yb,Tb phosphor. The luminescence intensity exhibits also a quadratic dependence on incident pump-laser power. However,
no green-emission has been observed in GdAl3(BO3)4 phosphors codoped with Yb3+/Tb3+ or Nd3+/Tb3+ respectively upon excited at 808 nm laser diode. A proposed upconversion mechanism involving energy transfer from Nd3+ to Yb3+, and then a cooperative energy transfer process from two excited Yb3+ to Tb3+ has been presented. 相似文献
7.
LiXun Yang Xin Xu LuYuan Hao XiuFang Yang Simeon Agathopoulos 《Journal of luminescence》2012,132(6):1540-1543
Oxynitride phosphor powders comprising of CaSi2O2N2 doped with Tb3+ were successfully synthesized using a high-temperature solid-state reaction method. The experimentally determined photoluminescence (PL) properties of the produced phosphors meet the requirements of 2D/3D plasma display panels (PDPs). In particular, under the excitation of vacuum ultraviolet (VUV) synchrotron radiation and ultraviolet (UV) irradiation, emission peaks corresponding to the 5D3→7FJ (J=6, 5, 4, 3) and 5D4→7FJ (J=6, 5, 4, 3) transitions of Tb3+ ions were recorded. Monitoring the 5D4→7F5 emission of Tb3+ at 545 nm, the excitation bands were assigned to the host-related absorption as well as the 4f–5d (fd) and the 4f–4f (ff) transitions of Tb3+. The produced phosphors can be efficiently excited at 147 nm, and have an adequately short decay time (τ1/10=1.14 ms). 相似文献
8.
Oxyfluoroborate glass co-doped with Eu and Yb ions has been prepared and characterized for its optical properties through
photoluminescence, absorption and lifetime measurements. An intense red upconversion is observed from the 5D0 level of Eu3+ ions through energy transfer from Yb3+ to Eu3+ ion when excited with 980 nm. The Judd–Ofelt parameters have been evaluated to estimate the local site symmetry around the
Eu3+ ions. These parameters have been used to derive radiative properties such as transition probabilities, branching ratios,
radiative lifetimes and stimulated emission cross-sections for the 5D0–7FJ transitions. Decay of excitation of the 5D0 level has been measured by monitoring the 5D0→7F2 transition (613 nm) at room temperature. Quantum efficiency for this transition is found to be 73%. We also monitored the
effect of temperature on the fluorescence emission of Eu3+.
PACS 42.70.Ce; 42.70.Hj 相似文献
9.
Nanocrystalline Y3Al5O12: Ce3+/Tb3+ (average crystalline size 30 nm) phosphor layers were coated on non-aggregated, monodisperse and spherical SiO2 particles by the sol-gel method, resulting in the formation of core-shell structured SiO2@Y3Al5O12:Ce3+/Tb3+ particles. X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, photoluminescence,
cathodoluminescence spectra, as well as lifetimes were utilized to characterize the core-shell structured SiO2@Y3Al5O12:Ce3+/Tb3+ phosphor particles. The obtained core-shell structured phosphors consist of well-dispersed submicron spherical particles
with a narrow size distribution. The thickness of the Y3Al5O12:Ce3+/Tb3+ shells on the SiO2 cores (average size about 500 nm, crystalline size about 30 nm) could be easily tailored by varying the number of deposition
cycles (100 nm for four deposition cycles). Under the excitation of ultraviolet and low-voltage electron beams (1–3 kV), the
core-shell SiO2@Y3Al5O12:Ce3+/Tb3+ particles show strong yellow-green and green emission corresponding to the 5d–4f emission of Ce3+ and 5D4–7F
J
(J = 6, 5, 4, 3) emission of Tb3+, respectively. These phosphors may have potential application in field emission displays. 相似文献
10.
L. R. P. Kassab F. A. Bomfim J. R. Martinelli N. U. Wetter J. J. Neto Cid B. de Araújo 《Applied physics. B, Lasers and optics》2009,94(2):239-242
We report the infrared-to-visible frequency upconversion in Er3+–Yb3+-codoped PbO-GeO2 glass containing silver nanoparticles (NPs). The optical excitation is made with a laser at 980 nm in resonance with the
2F5/2→2F7/2 transition of Yb3+ ions. Intense emission bands centered at 525, 550, and 662 nm were observed corresponding to Er3+ transitions. The simultaneous influence of the Yb3+→Er3+ energy transfer and the contribution of the intensified local field effect due to the silver NPs give origin to the enhancement
of the whole frequency upconversion spectra. 相似文献
11.
Photoluminescence spectra of CaWO4 doped with Pr3+ and Tb3+ obtained at high hydrostatic pressures up to 315 kbar applied in a diamond anvil cell (DAC) are presented. The intensities of the luminescence from the 3P0 state of Pr3+ and from the 5D3 state of Tb3+ decreased with increasing pressure. At pressures greater than 50 kbar, the 1D2 → 3HJ transitions in Pr3+ and the 5D4 → 7FJ transitions in Tb3+ dominated the spectra. At pressures greater than 100 kbar, only emissions from the lower excited states were observed. At pressures greater than 150 kbar, luminescence from the 1D2 and 5D4 states also decreased with increasing pressure, and at a pressure of 315 kbar for CaWO4:Pr3+ and 190 kbar for CaWO4:Tb3+, the emissions related to the Pr3+ and Tb3+ were quenched. These effects were related to the influence of impurity trapped excitons (ITEs) on the efficiency of the f–f emission in the Pr3+ and Tb3+ ions. Analysis of the emission spectra collected at different pressures allowed the energies of the ground states of the Pr3+ and Tb3+ ions with respect to the band edges of the CaWO4 host to be estimated. 相似文献
12.
XiaoBo Chen ZengFu Song JinGuang Wu N. Sawanoboi M. Ohtsuka YongLiang Li Jing Zhou Ce Wang JinYing Liu Qiang Tian Ping Sun HongMei Jing 《中国科学G辑(英文版)》2008,51(12):1868-1876
The ultraviolet upconversion luminescence of Tm3+ ions sensitized by Yb3+ ions in oxyfluoride nanophase vitroceramics when excited by a 975 nm diode laser was studied. An ultraviolet upconversion
luminescence line positioned at 363.6 nm was found. It was attributed to the fluorescence transition of 1D2→3H6 of Tm3+ ion. Several visible upconversion luminescence lines at 450.7 nm, (477.0 nm, 462.5 nm), 648.5 nm, (680.5 nm, 699.5 nm) and
(777.2 nm, 800.7 nm) were also found, which result respectively from the fluorescence transitions of 1D2→3F4, 1G4→3H6, 1G4→3F4, 3F3→3H6 and 3H4→3H6 of Tm3+ ion. The careful measurement and analysis of the variation of upconversion luminescence intensity F as a function of the 975 nm pumping laser power P prove that the upconversion luminescence of 1D2 state is partly a five-photon upconversion luminescence, and the upconversion luminescence of 1G4 state and 3H4 state are respectively the three-photon and two-photon upconversion luminescence. The theoretical analysis suggested that
the upconversion mechanism of the 363.6 nm 1D2→3H6 upconversion luminescence is partly the cross energy transfer of {3H4(Tm3+), 3F4(Tm3+), 1G4(Tm3+)→1D2(Tm3+)} and {1G4(Tm3+)→3F4(Tm3+), 3H4(Tm3+)→1D2(Tm3+)} between Tm3+ ions. In addition, the upconversion luminescence of 1G4 and 3H4 state results respectively from the sequential energy transfer {2F5/2(Yb3+)→2F7/2(Yb3+), 3H4(Tm3+)→1G4(Tm3+)} and {2F5/2(Yb3+) →2F7/2(Yb3+), 3F4(Tm3+)→3F2(Tm3+)} from Yb3+ ions to Tm3+ ions.
Supported by the National Natural Science Foundation of China (Grant No. 10674019) 相似文献
13.
The Ca12Al14O33: Yb3+/Yb2+ single phase nano-phosphor has been synthesized through combustion route and its luminescence and lifetime studies have been
carried out up to 20 K using 976 and 266 nm excitations. The samples heated in open atmosphere have shown the presence of
Yb in Yb3+ and Yb2+ states. The 976 nm excitation results a cooperative upconversion emission at 486 nm due to the Yb3+ state and a broad band in the blue region and has been assigned to arise from the defect centers. The 266 nm excitation on
the other hand results a broad emission band even from as-synthesized phosphor without doping of Yb, the width of which increases
in presence of Yb due to the emission from Yb2+ ions formed in heated samples. The white emission covers almost whole visible region with bandwidth 190 nm. The ions in Yb2+ state has been found to increase with the increase in heating temperature up to 1,273 K. A back conversion of Yb2+ to Yb3+ has been observed for higher temperatures. Effect of boric and phosphoric acids as flux on the emission properties of Yb3+ and Yb2+ states have been examined and discussed. Quantum yield of emission has also been determined for different samples. 相似文献
14.
Huijuan Liang 《Optics Communications》2009,282(14):3028-5456
Upconversion (UC) luminescence in monodisperse NaYF4:Yb3+/Tb3+ nanocrystals was observed under diode laser excitation of 970 nm, which were synthesized by a hydrothermal method. UC emissions at 380, 413, 436 nm and at 488, 542, 584, 620 nm arise from transitions 5D3(5G6) → 7FJ(J = 6, 5, 4) and 5D4 → 7FJ(J = 6, 5, 4, 3) of Tb3+ ions, respectively. UC mechanisms are proposed based on spectral, kinetic, decay time measurements, and pump power dependence analyses. Blue, green and red emissions originate from the same long-lived (milliseconds) upper 5D4 state, which promises the potential applications of these monodisperse Yb3+/Tb3+-codoped NaYF4 nanocrystals in the field of photonics, lasers and biomedicine. 相似文献
15.
A. Lushchik Ch. Lushchik I. Kudryavtseva A. Maaroos F. Savikhin E. Shablonin E. Vasil’chenko 《Optics and Spectroscopy》2011,111(3):434-440
The processes of photon multiplication in insulators have been considered. The luminescence of Tb3+ ions (5
D
3 → 7
F
J
, 5
D
4 → 7
F
J
transitions) upon intracenter excitation, the optical excitation of oxyanions, or the formation of separated electrons and
holes has been studied for CaSO4 doped with Tb3+ and Na+ ions at 6–9 K. An increase in Tb3+ concentration from 0.2 to 4 at % and transition from single Tb3+-Na+ states to centers that contain two or three terbium ions leads to the redistribution of the luminescence intensities in favor
of the 5
D
4 → 7
F
J
transitions and increase in their efficiency due to the possibility of the cooperative 5
D
3 → 5
D
4 and 7
F
6 → 7
F
J
transitions and the 4f
75d
1 → 5
D
3 and 7
F
6 → 5
D
4 transitions in the two- and three-terbium centers. Based on the example of MgO single crystals with highly mobile excitons,
holes, and electrons, the migration of free excitons and holes toward Cr3+ ions in the crystal bulk and their exit from the bulk to the surface have been revealed at 9 K. Surface losses limit the
luminescence quantum yield of MgO:Cr3+, CaSO4:Tb3+, and many other materials. 相似文献
16.
《Current Applied Physics》2015,15(12):1576-1579
Er3+/Yb3+-codoped SrMoO4 phosphors were prepared by a high-temperature solid-state reaction method. At room temperature, all the as-prepared samples exhibited strong upconversion properties and the emission intensity increased dramatically with the increase of Yb3+ ion concentration, reaching its maximum value when the concentration was 5 mol%. The dependence of emission intensity on the pump power suggested that the upconversion emission was a two-photon process. Furthermore, the optical temperature sensing properties based on green upconversion emissions of the SrMoO4:0.01Er3+/0.05Yb3+ phosphor were studied. It is found that the SrMoO4:0.01Er3+/0.05Yb3+ phosphor can be operated over a very wide temperature range of 93–773 K with a maximum sensitivity of ∼0.0128 K−1, indicating that low- and high-temperature thermometry can be simultaneously realized in this phosphor. 相似文献
17.
The Y2O3:R(R = Yb3+, Er3+, Tm3+) nanophosphors were synthesized by a solvothermal method and the temperature dependence of the white upconversion emission was studied using a 975 nm LD. The upconversion emission spectra in 1 mol% Er3+/5 mol% Yb3+/xTm3+ tri-doped Y2O3 nanophosphors were sintered at 1000 °C with x from 0 to 0.5 mol%. The blue emission intensity increases increasing Tm3+ concentration from 0 to 0.5 mol%, because the Tm3+ state can be easily reached due to the 2F7/2 → 2F5/2 transition of Yb3+ near 10,000 cm−1. The Y2O3: Er3+/Yb3+/Tm3+ nanophosphors exhibit upconversion emission from white to green with increasing sintering temperature. The calculated CIE coordinates are located in the white region at a pump power of 700 mW at 1000 °C, and the color coordinates were very similar to the standard white light emission. Their upconversion process was described through energy level diagrams and results of upconversion emission spectra and pump power dependence. 相似文献
18.
Lim Wei Qiang Shanmugan Subramani Devarajan Mutharasu 《Optical and Quantum Electronics》2016,48(2):1-9
Near infrared quantum cutting by cooperative energy transfer from Tb3+ to Yb3+ was investigated by photoluminescence measurements on (YbxY1?x)PO4 (x = 0, 0.05, 0.1, 0.15) doped with 1 % Tb3+. Under the excitation of 473 and 486 nm continuous wave lasers, we found that one Tb3+ ion absorbed one blue photon with the transition from 5D4 to 7F5 (λ ~ 544 nm) and cooperatively transfer energy to Yb3+ ions, which is followed by the emission of two photons (λ ~ 980 nm). Application of cooperative energy transfer has prospects for increasing the energy efficiency of crystalline Si solar cells by photon doubling of the high energy part of the solar spectrum.
相似文献19.
P. Haro-González I. R. Martín F. Lahoz N. E. Capuj 《Applied physics. B, Lasers and optics》2011,104(1):237-240
Evidence of positive optical gain is observed in Tm3+–Yb3+-codoped oxyfluoride glass ceramic in an upconversion pump and probe experiment. The 1G4 level of the Tm3+ ions is populated by an upconversion mechanism under excitation of the Yb3+ ions at 975 nm with a high-power pulsed laser and give rise to an intense emission from the 1G4 to the 3F4 levels. The 1G4→3F4 electronic transition is stimulated with a low signal at 650 nm as a probe. 相似文献
20.
P. Haro-González I.R. Martín S. González-Pérez M. Liu S.W. Wang N. Capuj F. Lahoz 《Journal of luminescence》2008,128(5-6):924-926
The YAG nanopowders were prepared by a co-precipitation method using nitrate and ammonium hydrogen carbonate as raw materials. To obtain homogenous precipitate, reverse-strike (adding salt solutions to the precipitant solution) technique was adopted. Therefore, single (Tm3+) and codoped (Tm3+–Yb3+) YAG nanopowders with a size between 40–90 nm have been obtained.Blue upconversion emission at around 480 nm has been found in YAG: Tm3+ nanopowders under excitation to the 3H4 level of Tm3+ at around 800 nm. However, this upconversion emission in nanopowders codoped with Tm3+–Yb3+ ions is increased by a factor of about 10. The analysis of the temporal evolution of the involved levels and the dependence of the upconversion intensity on the pump power at 800 nm allowed to distinguish the upconversion mechanism. In YAG: Tm3+ nanopowders the upconversion mechanism is due to excited state absorption processes. However, in the codoped samples, Yb3+ ions acts as the sensitizers; in consequence, the blue upconversion is strongly increased. 相似文献