NaBaPOM4:Tb3+绿色荧光粉制备及其发光特性

采用高温固相法合成了NaBaPOM₄:Tb³⁺绿色荧光粉, 并研究了材料的发光性质. NaBaPOM₄:Tb³⁺材料呈多峰发射, 发射峰位于437、490、543、587和624 nm, 分别对应Tb³⁺的⁵D₃→⁷F₄和⁵D₄→⁷F_{J=6, 5, 4, 3}跃迁发射, 主峰为543 nm; 监测543 nm发射峰, 所得激发光谱由4f⁷5d¹宽带吸收(200-330 nm)和4f-4f 电子吸收(330-400 nm)组成, 主峰为380 nm. 研究了Tb³⁺掺杂浓度, 电荷补偿剂Li⁺、Na⁺、K⁺和Cl^-, 及敏化剂Ce³⁺对NaBaPOM₄:Tb³⁺材料发射强度的影响. 结果显示: 调节激活剂浓度、添加电荷补偿剂或敏化剂均可以在很大程度上提高材料的发射强度.     

Temperature dependence of efficiency of energy transfer between Ce3+ → Tm3+ and Ce3+ → Tb3+ in phosphate glass

Energy transfer (ET) between Ce³⁺ → Tm³⁺ and Ce³⁺ and Ce³⁺ → Tb³⁺ in phosphate glass was measured in the temperature range 7–300 K. The efficiency of ET between Ce³⁺ and Tm³⁺ is independent of temperature, while temperature increase is observed in the Ce³⁺Tb³⁺ pair. This is explained by the increase with temperature of the overlap between Ce³⁺ emission and Tb³⁺ absorption bands.     

Electronic excitation energy transfer between Tb3+ and Eu3+ in DMSO

Excitation of Tb³⁺ and Eu³⁺ in DMSO with 487 mμ, which corresponds to the ⁷F₆ → ⁵D₄ transition of Tb³⁺, is accompanied by a reduction in the fluorescence efficiency of Tb³⁺ as [Eu³⁺] increases and by the appearance of a weak emission from Eu³⁺. An average rate constant for both the fluorescence quenching of Tb³⁺ and the energy transfer from Tb³⁺ to Eu³⁺ with subsequent emission from the latter, was found to be (2.2 ± 0.4) × 10³ M^?1 sec^?1.     

The luminescence of Pr3+ in BaY4Si5O17

The cell constants of four new monoclinic compounds BaR₄X₅O₁₇ (R = Y, Gd; X = Si, Ge) are given. The luminescence of various RE activators in the silicates is reported. Pr³⁺-activated BaY₄Si₅O₁₇ shows efficient ultraviolet 5d → 4f emission and weak 4f → 4f emission (mainly red luminescence from the ¹D₂ level). The 5d → 4f emission is ascribed to Pr³⁺ on Y sites, the 4f → 4f emission to Pr³⁺ on Ba sites. Energy transfer from Pr³⁺ to Gd³⁺ has been observed. Gd³⁺ plays an intermediate role in the energy transfer from Pr³⁺ to Sm³⁺ and to Dy³⁺ in BaGd₄Si₅O₁₇. Upon activation with Tb³⁺ the silicates show characteristic green Tb³⁺ luminescence with a quantum efficiency of 75% for ultraviolet excitation.     

Ca9Y(PO4)7:Ce3+,Tb3+纳米荧光粉的制备及发光性能

采用水热法制备出Ca₉Y（PO₄）₇：Ce³⁺,Tb³⁺纳米荧光粉,通过XRD、SEM和荧光光谱等对样品进行了分析,研究在Ca₉Y（PO₄）₇基质中引入Ce³⁺,Tb³⁺离子对发光性能的影响规律。研究发现因Tb³⁺离子自身能量交叉驰豫的存在,使得单掺Tb³⁺时,通过调节Tb³⁺离子的浓度可以实现对发光颜色的控制。同时研究了Ce³⁺-Tb³⁺之间的能量传递为电多极相互作用的偶极-四极机制,Ce³⁺-Tb³⁺之间最大的能量传递效率为55.6%。Ca₉Y（PO₄）₇：Ce³⁺,Tb³⁺的发光颜色可以通过激活离子之间的能量传递和共发射得到可控调节。SEM分析表明荧光粉颗粒尺寸在100 nm左右,分散性好。     

Emission spectra of Cs2NaTbCl6 and Cs2NaYCl6: Tb3+

The emission spectra of microcrystalline Cs₂NaTbCl₆ and Cs₂Na(Y_0.99Tb_0.01)Cl₆ have been measured at room temperature and at 77 K. The crystal structures of these compounds are face-centered cubic and the terbium (III) ions lie at sites of octahedral (O_h) symmetry surrounded by six chloride ions. Emission is observed from both the ⁵D₃ and ⁵D₄ excited states of Tb³⁺. Assignments have been made for nearly all of the magnetic-dipole transitions split out of the Tb³⁺⁷F₆, ⁷F₅, ⁷F₄, ⁷F₃, ⁷F₂, ⁷F₁ ← ⁵D₄ and ⁷F₄, ⁷F₂ ← ⁵D₃ transitions. These assignments are based on the calculated transition energies and relative magnetic-dipole strengths and intensities obtained from a weak-field crystal-field analysis of octahedral TbCl₆^3? units. Magnetic-dipole lines dominate the spectra for transitions of ΔJ = ±1 free-ion parentage, whereas both magnetic-dipole lines and vibronically induced electric-dipole lines contribute significantly to the emission intensities of the ΔJ = 0, ±2 transitions. The crystal-field sub-levels of both ⁵D₃ and ⁵D₄ appear to reach a Boltzmann thermal equilibrium prior to emission. Emission from ⁵D₃ is partially quenched in going from low temperature to high temperature and in going from Cs₂NaYCl₆: Tb³⁺ (1%) to Cs₂NaTbCl₆.This study has led to the identification and assignment of nearly all of the pure magnetic-dipole transitions split out of the Tb³⁺⁷F₆, ⁷F₅, ⁷F₄, ⁷F₃, ⁷F₂, ⁷F₁ ← ⁵D₄ and ⁷F₄, ⁷F₂ ← ⁵D₃ transitions in crystal-line Cs₂NaTbCl₆. The assignments were based on calculated transition energies and relative magnetic-dipole strengths (and intensities) obtained from a (weak-field) crystal-field analysis of octahedral (O_h) TbCl₆^3? clusters. Excellent agreement between the calculated and observed relative intensities of the magnetic-dipole lines was achieved by assuming a Boltzmann equilibrated set of crystal-field sub-levels for both the ⁵D₄ and ⁵D₃ emitting states. Furthermore, the experimental results suggest that ⁵D₄ ← ⁵D₃ relaxation is temperature-dependent.The energy levels calculated and displayed in table 1 appear to be qualitatively correct and are in semiquantitative agreement with the emission results (as interpreted in section 4). Calculated and observed transition energies for the assigned magnetic-dipole transitions generally agree to within 0.2%.One of the most remarkable features of the emission spectra obtained on Cs₂NaTbCl₆ is the absence of any vibrational structure in the ΔJ = ± 1 transitions (⁷F₆, ⁷F₃ ← ⁵D₄ and ⁷F₄, ⁷F₂ ← ⁵D₃), and the presence of extensive vibrational structure in the ΔJ = O, ±2 transitions (⁷F₆, ⁷F₄, ⁷F₂ ← ⁵D₄). If other than OO vibronic transitions do contribute to the ΔJ = ±1 emissions, their intensities must be at least two or three orders-of-magnitude weaker than the OO magnetic-dipole lines. Vibronically induced electric-dipole transitions appear, however, to make substantial contributions to the ⁷F₆, ⁷F₄, ⁷F₂ ← ⁵D₄ emission spectra. A clear-cut theoretical explanation for the absence of vibrational structure in the ΔJ = ±1 transitions is not readily apparent. We are presently examining this problem in greater detail.     

Preparation and luminescence properties of Ce and/or Tb doped LaPO4 nanofibers and microbelts by electrospinning

Ce³⁺ and/or Tb³⁺ doped LaPO₄ nanofibers and microbelts have been prepared by a combination method of sol-gel process and electrospinning. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), photoluminescence (PL), low voltage cathodoluminescence (CL) and time-resolved emission spectra as well as kinetic decays were used to characterize the resulting samples. SEM and TEM results indicate the as-formed precursor fibers and belts are smooth, and the as-prepared nanofibers and microbelts consist of nanoparticles. The doped rare-earth ions show their characteristic emission under ultraviolet excitation, i.e. Ce³⁺ 5d-4f and Tb³⁺⁵D₄-⁷F_J (J=6-3) transitions, respectively. The energy transfer process from Ce³⁺ to Tb³⁺ in LaPO₄:Ce³⁺, Tb³⁺ nanofibers was further studied by the time-resolved emission spectra. Under low-voltage electron beam excitation, LaPO₄:Ce³⁺, Tb³⁺ microbelt phosphors have a higher intensity than that of nanofiber phosphors.     

Nonradiative energy transfer from Tb3+ → Er3+ in calibo glass

Energy transfer studies have been made in a terbium-erbium coactivated calibo-glass system at room temperature and at liquid-air temperature. A study of the emission and decay of ⁵D₄ level of Tb³⁺ has been made by varying the acceptor (Er³⁺) concentration. Probabilities and efficiencies of energy transfer as well as donor-acceptor distances have been calculated. At low acceptor concentration the decay of the donor (Tb³⁺) emission has been found to be diffusion limited. At high acceptor concentration the mechanism governing the transfer is found to be dipole-dipole.     

Tb3+在MO(M=Ca,Sr)中的长余辉发光

长余辉发光材料的研究与应用，已有近100年的历史，目前仍在许多领域中有着重要应用。此类材料与其他光致发光材料具有相同的发光性能．只是更注重其发光的衰减过程和热释光性能。如．ZnS：Cu作为黄绿色的长余辉发光材料，在1992年以前是余辉性能最好的长余辉发光材料，一直处于发光研究工作的中心。     

La7O6(BO3)(PO4)2:Eu3+/Tb3+荧光材料的制备及其光致发光性能

采用优化的高温固相方法制备了稀土离子Eu³⁺和Tb³⁺掺杂的La₇O₆（BO₃）（PO₄）₂系荧光材料,并对其物相行为、晶体结构、光致发光性能和热稳定性进行了详细研究。结果表明,La₇O₆（BO₃）（PO₄）₂：Eu³⁺材料在紫外光激发下能够发射出红光,发射光谱中最强发射峰位于616 nm处,为⁵D₀→⁷F₂特征能级跃迁,Eu³⁺的最优掺杂浓度为0.08,对应的CIE坐标为（0.610 2,0.382 3）;La₇O₆（BO₃）（PO₄）₂：Tb³⁺材料在紫外光激发下能够发射出绿光,发射光谱中最强发射峰位于544 nm处,对应Tb³⁺的⁵D₄→⁷F₅能级跃迁,Tb³⁺离子的最优掺杂浓度为0.15,对应的CIE坐标为（0.317 7,0.535 2）。此外,对2种材料的变温光谱分析发现Eu³⁺和Tb³⁺掺杂的La₇O₆（BO₃）（PO₄）₂荧光材料均具有良好的热稳定性。     

UV-VUV-excited photoluminescence of RE-activated CaLaP3O10 (RE=Eu,Tb)

Monazite-type polyphosphate CaLaP₃O₁₀ was synthesized by solid-state reaction at 1000 °C and their photoluminescence of Eu³⁺ and Tb³⁺ in CaLaP₃O₁₀ under ultraviolet (UV) and vacuum-ultraviolet (VUV) excitation were evaluated for the first time. The emission spectra of CaLaP₃O₁₀:Eu³⁺showed that Eu³⁺ are in a site with inversion symmetry because the magnetic dipole transition ⁵D₀-⁷F₁ was the strongest both upon 254 and 147 nm excitation. Monitored at 621 nm the excitation spectra consisted of host absorption bands, charge transfer band of Eu-O and the intraconfiguration 4f⁶ transition of Eu³⁺. Green phosphor CaLaP₃O₁₀:Tb³⁺exhibited better color purity when excited by 147 nm than that excited by 254 nm. With monitored at 542 nm the host absorption bands of CaLaP₃O₁₀:Tb³⁺ were also observed. Besides the host absorption bands there were strong f-d and weak f-f transitions of Tb³⁺.     

Hydrothermal synthesis and luminescent properties of LuBO3:Tb microflowers

Hexagonal vaterite-type LuBO₃:Tb³⁺ microflower-like phosphors have been successfully prepared by an efficient surfactant- and template-free hydrothermal process directly without further sintering treatment. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectrometry, transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), photoluminescence (PL) and cathodoluminescence (CL) spectra as well as kinetic decays were used to characterize the samples. The as-obtained phosphor samples present flowerlike agglomerates composed of nanoflakes with thickness of 40 nm and high crystallinity in spite of the moderate reaction temperature of 200 °C. The reaction mechanism has been considered as a dissolution/precipitation mechanism; the self-assembly evolution process has been proposed on homocentric layer-by-layer growth style. Under ultraviolet excitation into the 4f⁸→4f⁷5d transition of Tb³⁺ at 248 nm (or 288 nm) and low-voltage electron beam excitation, LuBO₃:Tb³⁺ samples show the characteristic green emission of Tb³⁺ corresponding to ⁵D₄→⁷F_{6, 5, 4, 3} transitions with the ⁵D₄→⁷F₅ transition (542 nm) being the most prominent group, which have potential applications in fluorescent lamps and field emission displays.     

空气中合成固溶体荧光粉Ba2(Zn, Mg)Si2O7:Ce3+,Eu2+,Eu3+及其发光特性

采用高温固相法在空气中合成了Ba_1.97-yZn_1-xMg_xSi₂O₇:0.03Eu,yCe³⁺系列荧光粉。分别采用X-射线衍射和荧光光谱对所合成荧光粉的物相和发光性质进行了表征。在紫外光330~360 nm激发下,固溶体荧光粉Ba_1.97-yZn_1-xMg_xSi₂O₇:0.03Eu的发射光谱在350~725 nm范围内呈现多谱峰发射,360和500 nm处有强的宽带发射属于Eu²⁺离子的4f⁶5d¹-4f⁷跃迁,590~725 nm红光区窄带谱源于Eu³⁺的⁵D₀-⁷F_J (J=1,2,3,4)跃迁,这表明,在空气气氛中,部分Eu³⁺在Ba_1.97-yZn_1-xMg_xSi₂O₇基质中被还原成了Eu²⁺;当x=0.1时,荧光粉Ba_1.97Zn_0.9Mg_0.1Si₂O₇:0.03Eu的绿色发光最强,表明Eu³⁺被还原成Eu²⁺离子的程度最大。当共掺入Ce³⁺离子后,形成Ba_1.97-yZn_0.9Mg_0.1Si₂O₇:0.03Eu,yCe³⁺荧光粉体系,其发光随着Ce³⁺离子浓度的增大由蓝绿区经白光区到达橙红区;发现名义组成为Ba_1.96Zn_0.9Mg_0.1Si₂O₇:0.01Ce³⁺,0.03Eu的荧光粉的色坐标为(0.323,0.311),接近理想白光,是一种有潜在应用价值的白光荧光粉。讨论了稀土离子在Ba₂Zn_0.9Mg_0.1Si₂O₇基质中的能量传递与发光机理。     

Crystal, electronic structures and photoluminescence properties of rare-earth doped LiSi2N3

The crystal and electronic structures, and luminescence properties of Eu²⁺, Ce³⁺ and Tb³⁺ activated LiSi₂N₃ are reported. LiSi₂N₃ is an insulator with an indirect band gap of about 5.0 eV (experimental value ∼6.4 eV) and the Li 2s, 2p states are positioned on the top of the valence band close to the Fermi level and the bottom of the conduction band. The solubility of Eu²⁺ is significantly higher than Ce³⁺ and Tb³⁺ in LiSi₂N₃ which may be strongly related to the valence difference between Li⁺ and rare-earth ions. LiSi₂N₃:Eu²⁺ shows yellow emission at about 580 nm due to the 4f⁶5d¹→4f⁷ transition of Eu²⁺. Double substitution is found to be the effective ways to improve the luminescence efficiency of LiSi₂N₃:Eu²⁺, especially for the partial replacement of (LiSi)⁵⁺ with (CaAl)⁵⁺, which gives red emission at 620 nm, showing highly promising applications in white LEDs. LiSi₂N₃:Ce³⁺ emits blue light at about 450 nm arising from the 5d¹→4f¹5d⁰ transition of Ce³⁺ upon excitation at 320 nm. LiSi₂N₃:Tb³⁺ gives strong green line emission with a maximum peak at about 542 nm attributed to the ⁵D₄→⁷F_J (J=3-6) transition of Tb³⁺, which is caused by highly efficient energy transfer from the LiSi₂N₃ host to the Tb³⁺ ions.     

Hydrothermal synthesis of core-shell structured PS@GdPO<Subscript>4</Subscript>:Tb<Superscript>3+</Superscript>/Ce<Superscript>3+</Superscript> spherical particles and their luminescence properties

Non-aggregated spherical polystyrene (PS) particles were coated with GdPO₄:Tb³⁺/Ce³⁺ phosphor layers by a conventional hydrothermal synthesis using poly(vinylpyrrolidone) (PVP) as an additive without further annealing treatment. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), photoluminescence (PL), as well as luminescence decay experiments were used to characterise the resulting core-shell structured PS@GdPO₄:Tb³⁺/Ce³⁺ samples. The results of XRD indicated that the PS particles were successfully coated with the GdPO₄:Tb³⁺/Ce³⁺ phosphor layers, which could be further verified by the images of FESEM. Under ultraviolet excitation, the PS@GdPO₄:Tb³⁺/Ce³⁺ phosphors show Tb³⁺ characteristic emission, i.e. ⁵D₄-⁷F_J (J = {6, 5, 4, 3}) emission lines with green emission ⁵D₄-⁷F₅ (543 nm) as the most prominent group. The core-shell phosphors so obtained have potential applications in field emission display (FED) and plasma display panels (PDP).     

Sol-gel deposition and luminescent properties of LaMgAl11O19:Ce/Tb phosphor films

Rare earth ions (Ce³⁺, Tb³⁺)-doped LaMgAl₁₁O₁₉ phosphor films were deposited on quartz glass substrates by Pechini sol-gel and dip coating method. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric and differential thermal analysis (TG-DTA), atomic force microscopy (AFM), field emission scanning electronic microscopy (FESEM), photoluminescence (PL) spectra, and lifetimes were used to characterize the resulting films. The results of XRD indicated that the magnetoplumbite structure LaMgAl₁₁O₁₉ phase can be obtained at 1200 °C on quartz glass substrates. This was further verified by the results of FT-IR and TG-DTA. AFM study showed that uniform films have an average grain size of 150 nm and a root mean square (RMS) roughness of 4 nm. The thickness of the films characterized by FESEM is about 340 nm. LaMgAl₁₁O₁₉:Ce³⁺ film showed the parity and spin allowed 5d-4f band emission of Ce³⁺ with a maximum at 350 nm. Ce³⁺, Tb³⁺-codoped LaMgAl₁₁O₁₉ films showed the band emission of Ce³⁺ and characteristic emission of Tb³⁺, namely, ⁵D_3,4-⁷F_J (J=6, 5, 4, 3) due to an efficient energy transfer from Ce³⁺ to Tb³⁺ in the host.     

Ca9Y(PO4)7:Ce3+,Tb3+纳米荧光粉的制备及发光性能

采用水热法制备出Ca_9Y(PO4)7∶Ce~(3+),Tb~(3+)纳米荧光粉,通过XRD、SEM和荧光光谱等对样品进行了分析,研究在Ca_9Y(PO4)7基质中引入Ce~(3+),Tb~(3+)离子对发光性能的影响规律。研究发现因Tb~(3+)离子自身能量交叉驰豫的存在,使得单掺Tb~(3+)时,通过调节Tb~(3+)离子的浓度可以实现对发光颜色的控制。同时研究了Ce~(3+)-Tb~(3+)之间的能量传递为电多极相互作用的偶极-四极机制,Ce~(3+)-Tb~(3+)之间最大的能量传递效率为55.6%。Ca_9Y(PO4)7∶Ce~(3+),Tb~(3+)的发光颜色可以通过激活离子之间的能量传递和共发射得到可控调节。SEM分析表明荧光粉颗粒尺寸在100 nm左右,分散性好。     

Homogeneous one-dimensional structured Tb(OH)3:Eu nanorods: Hydrothermal synthesis, energy transfer, and tunable luminescence properties

Nearly monodisperse, homogeneous and well-defined one-dimensional Tb_(1−x)(OH)₃:xEu³⁺ (x=0-3 mol%) nanorods have been prepared through hydrothermal method. The size of the Tb(OH)₃:Eu³⁺ rods could be modulated from nano- to micro-scale by using different amount of ammonia solution. They present highly crystallinity in spite of the moderate reaction temperature. Under ultraviolet excitation into the f→f transition of Tb³⁺ at 382 nm, Tb(OH)₃ samples show the characteristic emission of Tb³⁺ corresponding to ⁵D₄→⁷F_{6, 5, 4, 3} transitions; whereas Tb(OH)₃:Eu³⁺ samples mainly exhibit the characteristic emission of Eu³⁺ corresponding to ⁵D₀→⁷F_{1, 2, 4} transitions due to an efficient energy transfer occurs from Tb³⁺ to Eu³⁺. The increase of Eu³⁺ concentration leads to the increase of the energy transfer efficiency from Tb³⁺ to Eu³⁺. The PL colors of Tb(OH)₃:xEu³⁺ phosphors can be easily tuned from green, yellow, orange, to red by changing the doping concentration (x) of Eu³⁺.     

Eu+2 fluorescence in BaCl2

The Ba_1?xEu_xCl₂ system was studied over wide ranges of x, particularly regarding the fluorescent emission of Eu²⁺. In addition to the commonly observed 5d → 4f band emission sharp line, f → f transitions were observed. Single crystals of Eu²⁺ containing BaCl₂ were grown via the Czochralski technique and many of the optical properties, such as transmission, fluorescence, and excitation, were measured. X-ray and thermal parameters for the Ba_1?xEu_xCl₂ system are also reported.     

Photoluminescence of Ce, Pr and Tb activated Sr3Ln(PO4)3 under VUV-UV excitation

The spectroscopic properties in VUV-Vis range for the eulytite structural phosphors Sr₃Gd(PO₄)₃:Ln³⁺ (Ln³⁺=Ce³⁺, Pr³⁺, Tb³⁺), Sr₃Ce(PO₄)₃, Sr₃Gd(PO₄)₃ and Sr₃Tb(PO₄)₃ were investigated. The bands near 170 nm in VUV excitation spectra are assumed to connect with the host lattices related absorption. The f-d transitions of Ce³⁺, Pr³⁺ and Tb³⁺ in the host lattices are assigned and corroborated. A convenient experiment formulation on the relationship between the lowest f-d transition energies and n value for trivalent 4fⁿ-series rare earth ions in these host lattices is applied.