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1.
Trivalent dysprosium ions (Dy3+) doped strontium molybdate (SrMoO4) phosphors were synthesized by solid-state reaction and their photoluminescence (PL) properties were investigated. X-ray powder diffraction (XRD) analysis confirmed the formation of SrMoO4:Dy3+. PL measurements indicated that the phosphor exhibited intense emission at 482, 490 (4F9/2→6H15/2) and 575 nm (4F9/2→6H13/2) under UV excitation. The effect of the doping concentration of Dy3+in SrMoO4:Dy3+ on the PL was investigated in detail. Na+ ion was a good charge compensator for SrMoO4:Dy3+. 相似文献
2.
V.P. Solntsev A.P. YelisseyevT.B. Bekker A.E. KokhS. Yu. Stonoga A.V. DavydovA. Maillard 《Optics Communications》2012,285(24):5205-5209
Optical absorption and luminescence spectra of ytterbium and terbium codoped BaB2O4 (β-BBO and α-BBO) crystals grown in different conditions have been studied. Low-temperature absorption peaks were observed in all samples. Features related to rare earth ions were observed in absorption and luminescence spectra. Absorption and emission in the range 860-1000 nm are caused by 2F5/2↔2F7/2 transitions in Yb3+ ions. Emission peaks at 500, 550, 590 and 630 nm correspond to 5D4→7F6, 7F5, 7F4, and 7F3 transitions of Tb3+ ions, respectively. The probable reasons of variations in spectroscopic features related to Yb in BBO host are discussed. It has been shown that the replacement of Ва2+ by Yb3+ in the lattice of ВаВ2О4 results in the decrease in the symmetry of oxygen surrounding of Yb3+. 相似文献
3.
Yuyang He Maiqun Zhao Yanyan Song Gaoyang Zhao Xuan Ai 《Journal of luminescence》2011,131(6):1144-1148
Y0.99−xPO4:0.01Dy3+, xBi3+ (x=0, 0.01, 0.05, 0.10, 0.15, 0.20 and 0.25) phosphors have been synthesized by a modified chemical co-precipitation method using urea as a pH value regulator. The samples were characterized by X-ray powder diffraction (XRD) and photoluminescence spectroscopy. XRD results show that the samples have only single tetragonal structure when x≤0.15, but extraneous BiPO4 phase appears besides major tetragonal phase when x≥0.20. The crystallinity of the samples is found to improve with increasing Bi3+ ion concentration from 0 to 15 mol%, and then decreased for higher concentrations associated with increasing BiPO4 phase. Photoluminescence excitation spectra results show that the phosphor can be efficiently excited by ultraviolet light from 250 to 400 nm including four peaks at 294, 326, 352 and 365 nm. Emission spectra exhibit strong blue emission (483 nm) and another strong yellow emission (574 nm). When the Bi3+ ion concentration is 1 mol%, the intensity of excitation and emission spectra increased evidently. In addition, the yellow-to-blue emission intensity ratio (IY/IB) is strongly related to the excitation wavelength and not to the Bi3+ ion concentration. 相似文献
4.
Ionoluminescence (IL) of nano crystalline Mg2SiO4:Dy3+ pellet samples bombarded with 100 MeV Si+8 ions with fluences in the range (1.124–22.480) × 1012 ions cm−2 have been studied. Two prominent IL bands with peaks at ∼480 nm and ∼580 nm and a weak band with peak at ∼670 nm are recorded. The characteristic peaks are attributed to luminescence center activated by Dy3+ ions due to the transitions 4F9/2→6H15/2,6H13/2 and 6H11/2. It is found that IL intensity initially decreases rapidly and then continuous to decrease slowly with further increase in ion fluence. The reduction in the Ionoluminescence intensity with increase of ion fluence might be attributed to degradation of Si–O ( 2ν3) bonds present on the surface of the sample and/or due to lattice disorder produced by dense electronic excitation under heavy ion irradiation. 相似文献
5.
H.C. Swart O.M. NtwaeaborwaP.D. Nsimama J.J. Terblans 《Physica B: Condensed Matter》2012,407(10):1660-1663
SrAl2O4:Eu2+, Dy3+ thin films were grown on Si (1 0 0) substrates in different atmospheres using the pulsed laser deposition (PLD) technique. The effects of vacuum, oxygen (O2) and argon (Ar) deposition atmospheres on the structural, morphological and photoluminescence (PL) properties of the films were investigated. The films were ablated using a 248 nm KrF excimer laser. Improved PL intensities were obtained from the unannealed films prepared in Ar and O2 atmospheres compared to those prepared in vacuum. A stable green emission peak at 520 nm, attributed to 4f65d1→4f7 Eu2+ transitions was obtained. After annealing the films prepared in vacuum at 800 °C for 2 h, the intensity of the green emission (520 nm) of the thin film increased considerably. The amorphous thin film was crystalline after the annealing process. The diffusion of adventitious C into the nanostructured layers deposited in the Ar and O2 atmospheres was most probably responsible for the quenching of the PL intensity after annealing. 相似文献
6.
测量了Tm3+离子不同浓度(0.5at.%, 3 at.%, 5 at.%)掺杂的NaY(WO4)2晶体在800nm激光二极管激发下的上转换发射光谱.结合吸收谱、荧光谱和由Judd-Ofelt理论计算的光谱参数,详细分析了Tm3+:NaY(WO4)2晶体中上转换能量传递机理和离子浓度对上转换发射的影响.讨论了四种影响上转换发光效率的离子间相互作用机理:3H5+1G4→3H6+1D2,3H5+3H5→3H6+3F3,1G4+3H6→3F4+3F3,1G4+3H6→3F3+3F4,并根据Miyakawa-Dexter理论定量计算了各过程的发生概率.论证了交叉弛豫和共协上转换等浓度猝灭效应是影响Tm3+离子蓝色上转换荧光发射效率的主要因素.
关键词:
3+离子')" href="#">Tm3+离子
4)2晶体')" href="#">NaY(WO4)2晶体
上转换
浓度猝灭 相似文献
7.
Results of the optical spectroscopy investigation of the cubic paramagnetic center Yb3+ ion in the Cs2NaYF6 single crystal are presented. The Stark level energies of the Yb3+ multiplets are established from absorption, luminescence and excitation luminescence spectra and the crystal field parameters are calculated. Information about the phonon spectra of Cs2NaYF6 crystals is obtained from the electron-vibrational structure of the optical absorption and luminescence spectra. 相似文献
8.
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
9.
Dysprosium ion doped fluorophosphate glasses with compositions of PKMAFDy: (56−x/2) P2O5+17K2O+8Al2O3+(15−x/2)MgO+4AlF3+xDy2O3 (x=0.01, 0.05, 0.1, 1.0 and 2.0 mol%) have been prepared by melt quenching technique and are characterized by optical absorption, emission spectra and fluorescence lifetime measurements. The observed bands in the absorption spectrum are analysed by using free-ion Hamiltonian (HFI) model. The Judd-Ofelt (JO) analysis has been performed and the intensity parameters (Ωλ, λ=2, 4, 6) have been evaluated that are used to predict radiative properties. From emission spectra, the effective bandwidth (Δλeff) and the stimulated emission cross-section (σ(λp)) were evaluated. The fluorescence decay from the 4F9/2 level of Dy3+ ions have been measured by monitoring the intense 4F9/2→6H13/2 transition (573 nm). The lifetimes (τ) are found to decrease with increasing concentration due to concentration quenching. The decay curves are single exponential for lower concentrations and gradually changes to non-exponential for higher concentrations. The non-exponential decay curves are well fitted to the Inokuti-Hirayama (IH) model for S=6 which indicates that the energy transfer between the donor and acceptor is of dipole-dipole type. The systematic analysis on decay measurements reveals that the energy transfer mechanism strongly depends on concentration as well as glass composition. 相似文献
10.
B.M. Mothudi O.M. Ntwaeaborwa A. Kumar K. Sohn H.C. Swart 《Physica B: Condensed Matter》2012,407(10):1679-1682
Long persistent SrAl2O4:Eu2+ phosphors co-doped with Dy3+ were prepared by the solid state reaction method. The main diffraction peaks of the monoclinic structure of SrAl2O4 were observed in all the samples. The broad band emission spectra at 497 nm for SrAl2O4:Eu2+, Dy3+ were observed and the emission is attributed to the 4f65d1 to 4f7 transition of Eu2+ ions. The samples annealed at 1100–1200 °C showed similar broad TL glow curves centered at 120 °C. The similar TL glow curves suggest that the traps responsible for them are similar. The long afterglow displayed by the phosphors annealed at different temperatures, may be attributed to the Dy3+ ions acting as the hole trap levels, which play an important role in prolonging the duration of luminescence. 相似文献
11.
SrAl2O4:Eu2+,Dy3+ thin films were grown on Si (1 0 0) substrates using the pulsed laser deposition (PLD) technique to investigate the effect of vacuum, oxygen (O2) and argon (Ar) deposition atmospheres on the structural, morphological, photoluminescence (PL) and cathodoluminescence (CL) properties of the films. The films were ablated using a 248 nm KrF excimer laser. Atomic force microscopy (AFM), scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS) and fluorescence spectrophotometry were used to characterize the thin films. Auger electron spectroscopy (AES) combined with CL spectroscopy were employed for the surface characterization and electron-beam induced degradation of the films. Better PL intensities were obtained from the unannealed films prepared in Ar and O2 atmospheres with respect to those prepared in vacuum. A stable green emission peak at 515 nm, attributed to 4f65d1→4f7 Eu2+ transitions were obtained with less intense peaks at 619 nm, which were attributed to transitions in Eu3+. After annealing the films prepared in vacuum at 800 °C for 2 h, the intensity of the green emission (520 nm) of the thin film increased considerably. The amorphous thin film was crystalline after the annealing process. The CL intensity increased under prolonged electron bombardment during the removal of C due to electron stimulated surface chemical reactions (ESSCRs) on the surface of the SrAl2O4:Eu2+, Dy3+ thin films. The CL stabilized and stayed constant thereafter. 相似文献
12.
The current work reports on the influence of the number of laser pulses on the morphological and photoluminescence properties of SrAl2O4:Eu2+,Dy3+ thin films prepared by the pulsed laser deposition (PLD) technique. Atomic force microscopy (AFM) was used to study the surface topography and morphology of the films. The AFM data showed that the film deposited using a higher number of laser pulses was packed with a uniform layer of coarse grains. In addition, the surface of this film was shown to be relatively rougher than the films deposited at a lower number of pulses. Photoluminescence (PL) data were collected using the Cary Eclipse fluorescence spectrophotometer equipped with a monochromatic xenon lamp. An intense green photoluminescence was observed at 517 nm from the films prepared using a higher number of laser pulses. Consistent with the PL data, the decay time of the film deposited using a higher number of pulses was characteristically longer than those of the other films. The effects of laser pulses on morphology, topography and photoluminescence intensity of the SrAl2O4:Eu2+,Dy3+ thin films are discussed. 相似文献
13.
H.C. Swart J.J. Terblans O.M. Ntwaeaborwa R.E. Kroon B.M. Mothudi 《Physica B: Condensed Matter》2012,407(10):1664-1667
Strontium aluminate phosphors are ideal for luminescent infrastructure materials. Their brightness and persistent glow time are much higher than previously used sulphide phosphors. Strontium aluminates prepared by the sol–gel and combustion methods are compared with commercially available strontium aluminate. High luminescent efficient SrAl2O4:Eu2+,Dy3+ pulsed laser deposited (PLD) thin films were also produced using the commercially available powder. Photoluminescence (PL) degradation studies showed that the phosphor intensity decreased about 20% over a period of 2 weeks under ultraviolet (UV) irradiation. Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) showed that cathodoluminescence (CL) degradation is due to the formation of SrO due to electron stimulated surface reactions. The light output mechanism of the phosphor is also discussed in more detail. 相似文献
14.
Yumashev K. V. Posnov N. N. Prokoshin P. V. Kalashnikov V. L. Mejid F. Poloyko I.G. Mikhailov V. P. Kozich V. P. 《Optical and Quantum Electronics》2000,32(1):43-48
The nonlinear refractive index n2 of Yb3+:KY(WO4)2 crystal has been measured using picosecond Z-scan technique. The magnitude of n2 was found to be 8.7 × 10–16 cm2/W at wavelength of 1.08 m. The numerical modeling based on fluctuation model showed a great potential of this crystal as active medium for Kerr-lens mode-locking. 相似文献
15.
F. Güell 《Journal of luminescence》2004,106(2):109-114
Up-conversion blue emissions of trivalent thulium ions in monoclinic KGd(WO4)2 single crystals at 454 and 479 nm are reported for a single pump laser source at 688 nm. We grew thulium-doped KGd(WO4)2 single crystals at several concentrations from 0.1% to 10%. We recorded a polarized optical absorption spectrum for the 3F2+3F3 energy levels of thulium at room temperature and low temperature (6 K). From the low temperature emission spectra we determined the splitting of the 3H6 ground state. The blue emissions are characterized as a function of the dopant concentration and temperature from 10 K to room temperature. To our knowledge, this is the first time that sequential two-photon excitation process (STEP) generated blue emissions in thulium-doped single crystals with a single excitation wavelength. 相似文献
16.
Guojian Wang Zhoubin Lin Lizhen Zhang Yisheng Huang Guofu Wang 《Journal of luminescence》2009,129(11):1398-1400
This paper reports the spectral properties and energy levels of Cr3+:Sc2(MoO4)3 crystal. The crystal field strength Dq, Racah parameter B and C were calculated to be 1408 cm−1, 608 cm−1 and 3054 cm−1, respectively. The absorption cross sections σα of 4A2→4T1 and 4A2→4T2 transitions were 3.74×10−19 cm2 at 499 nm and 3.21×10−19 cm2 at 710 nm, respectively. The emission cross section σe was 375×10−20 cm2 at 880 nm. Cr3+:Sc2(MoO4)3 crystal has a broad emission band with a broad FWHM of 176 nm (2179 cm−1). Therefore, Cr3+:Sc2(MoO4)3 crystal may be regarded as a potential tunable laser gain medium. 相似文献
17.
Xianhua Qian Dafeng Zhang Lei Li Meijing Li Shutong Wu 《Journal of luminescence》2011,131(8):1692-1695
The red phosphors NaY1−xEux(WO4)2 with different concentrations of Eu3+ were synthesized via the combustion synthesis method. As a comparison, NaEu(WO4)2 was prepared by the solid-state reaction method. The phase composition and optical properties of as-synthesized samples were studied by X-ray powder diffraction and photoluminescence spectra. The results show that the red light emission intensity of the combustion synthesized samples under 394 nm excitation increases with increase in Eu3+ concentrations and calcination temperatures. Without Y ions doping, the emission spectra intensity of the NaEu(WO4)2 phosphor prepared by the combustion method fired at 900 °C is higher than that prepared by the solid-state reaction at 1100 °C. NaEu(WO4)2 phosphor synthesized by the combustion method at 1100 °C exhibits the strongest red emission under 394 nm excitation and appropriate CIE chromaticity coordinates (x=0.64, y=0.33) close to the NTSC standard value. Thus, its excellent luminescence properties make it a promising phosphor for near UV InGaN chip-based red-emitting LED application. 相似文献
18.
The spectroscopic characteristics and fluorescence dynamics for Yb3+/Ho3+:NaY(WO4)2 crystal were investigated. The parameters of oscillator strengths, the spontaneous transition probabilities, the fluorescence branching ratios, the radiative lifetimes and the stimulated emission cross sections have been calculated based on Judd-Ofelt theory and Füchtbauer-Ladenburg method. The energy transfer efficiency from Yb3+ to Ho3+ was 65.85%. The green emission (530-570 nm) corresponding to (5F4, 5S2)→5I8 transition, red emission (640-670 nm) due to 5F5→5I8 transition and NIR emission (740-770 nm) attributed to (5F4, 5S2)→5I7 transition were observed on 974 nm excitation at room temperature. Under low pump power, the intensity of green light emission is weaker than that of the red light, while under high pump power, the case is on the contrary. The upconversion is based on the two-photon process either the energy transfer from Yb3+ ions or by the excited state absorption. The proposed mechanisms of upconversion emissions were provided. 相似文献
19.
Auger electron/X-ray photoelectron and cathodoluminescent (CL) spectroscopic studies were conducted on pulsed laser deposited SrAl2O4:Eu2+,Dy3+ thin films and the correlation between the surface chemical reactions and the decrease in the CL intensity was determined. The Auger electron and the CL data were collected simultaneously in a vacuum chamber either maintained at base pressure or backfilled with oxygen gas. The data were collected when the films were irradiated for 14 h with 2 keV electrons. The CL emission peak attributed to the 4f65d1 → 4f7 transitions was observed at ∼521 nm and the CL intensity of the peaks degraded at different rates in different vacuum conditions. X-ray photoelectron spectroscopy (XPS) data collected from degraded films suggest that strontium oxide (SrO) and aliminium oxide (Al2O3) were formed on the surface of the film as a result of electron stimulated surface chemical reaction (ESSCR). 相似文献
20.
《Journal of luminescence》2004,106(2):77-90
The optical properties of the low-field sites of Cr3+-doped alkali (Li, Na, K) disilicate glasses have been investigated using the single configurational coordinate model. The assumption of a Gaussian site distribution for the Cr3+ ions taking as parameter the zero-phonon energy has been considered. For alkali disilicate glasses the inhomogeneous contribution to the broadening of the bands, associated to the site distribution, is lower than the homogeneous one. The electron-lattice coupling S and the mean phonon energy ?ω0 have been obtained with results around 4 and 500 cm−1, respectively, similar to those obtained by other authors in oxide glasses. The site-resolved study of the emission and excitation spectra and the luminescence decay curves have been carried out as a function of temperature. On the one hand, there is evidence of a non-radiative de-excitation process that becomes important over 140 K. On the other hand, and related to the site dependence of the radiative and non-radiative probabilities, different results involving low values for the quantum efficiencies and blue shifts of the emission bands as temperature increases have been explained. Besides, the non-exponential luminescence decay curves have been fitted to an expression proposed by the authors, which takes into account non-coupled distributions for the radiative and non-radiative de-excitation probabilities for the range of temperature covering from 13 to 300 K. From the fits, the temperature dependence of the non-radiative de-excitation probability is obtained for each disilicate glass, the results are in good agreement with the expression obtained assuming the harmonic approximation in the single configurational coordinate model. 相似文献