Spectrum of Tb3+ ion in LaBr3 crystal

The absorption and fluorescence spectra of 5 % Tb³⁺ ions in lanthanum bromide anhydrous crystal have been studied at 77 °K. The fluorescence groups in the regions 3800–4820 Å and 4880–6780 Å have been interpreted as arising from transitions from ⁵D₃ and ⁵D₄ respectively to the Stark components of ⁷F levels. Twenty-seven out of thirty-three components of ⁷F levels, five out of six components of ⁵D₃ have been obtained from the analysis.     

Spectrum of Tb3+ ion in terbium aluminium garnet

The absorption and fluorescence spectra of trivalent terbium ions in terbium aluminium garnet have been studied at 77 °K and 4 °K. The absorption spectrum led to the determination of two excited states, ⁵D₃ and ⁵D₄. The fluorescence spectrum observed in the region 4800–6800 Å is interpreted as due to transitions from the Stark components of the ⁵D₄ level to the Stark components of all the ⁷F levels. The numbers of Stark components identified are six for ⁵D₄ and forty-one for ⁷F levels. The analysis of the spectra indicates that the symmetry around terbium ions is lower than tetragonal, probably orthorhombic.     

Luminescence of Tb3+ ions in silicate glasses

The optical absorption and photoluminescence emission spectra of terbium doped sodium and lithium aluminium silicate glasses have been measured as a function of terbium concentration. Optical absorption has been measured over the wavelength range from 250 nm to 40 μm and the absorption bands attributed to Tb³⁺ ions have been identified. Luminescence emission occurs in two groups of bands in the blue and in the green. The green ⁵D₄ → ⁷F_J emission is more intense than the blue ⁵D₃ → ⁷F_J. The green luminescence is enhanced at the expense of the blue when the Tb³⁺ ion concentration reaches 0.5 molar%, which corresponds to an ion separation of 20 Å. The green emission is quenched when the Tb³⁺ ion concentration exceeds 5 molar%, corresponding to an ion separation of 9.5 Å. It is concluded that energy transfer from ⁵D₃ to ⁵D₄ levels begins at Tb³⁺ ion separations of 20 Å, and that the process is multipolar. Exchange dipole processes set in at 9.5 Å and quench the green emission. The ion separations at which the two processes occur in silicate glasses are much larger than those at which similar processes set in crystalline material. This enhancement of energy transfer processes in silicate glass is attributed to inhomogeneous broadening of the absorption and emission bands. The detailed structure of the emission bands, particularly that of the ⁵D₄ → ⁷F_6,5,4 doublets, is used to suggest that the Tb³⁺ ions occupy two different sites with rhombohedral and cubic symmetries.     

X-ray excited optical luminescence in the yttrium-gadolinum-terbium phosphate system

The X-ray excited optical luminescence of Tb in YPO₄ present at 0.01 mol Tb₂O₃/mol Y₂O₃ was found to consist primarily of emission in the 3800–4500 Å region arising from 5D₃ → 7FJ transitions of Tb³⁺. This luminescence was in addition found to be sensitized by Gd. Preliminary tests on the radiographic properties of the Y_0.8Gd_0.2PO₄: Tb³⁺ composition show that this phosphor offers promise as an efficient radiographic screen phosphor.     

Pressure-dependent luminescence properties of Tb3+-doped K–Ba–Al fluorophosphate glass

Tb³⁺-doped fluorophosphate glass with a composition of P₂O₅+K₂O+KF+BaO+Al₂O₃+Tb₄O₇ was prepared by melt quenching technique and characterized through emission spectra and decay curves as a function of pressure up to 37.7 GPa. The ⁵D₄→⁷F₃, ⁷F₄ and ⁷F₅ emission transitions shift toward lower energy in the order of?4.7,?2.4 and?4.0 cm^?1 GPa^?1, respectively, with increasing pressure. A strong increase in the splitting of the ⁵D₄→⁷F₅ Stark levels with pressure is observed. The decay curves for the ⁵D₄ level are found to be almost perfectly single exponential in the entire pressure range studied. Lifetimes of the ⁵D₄ level are found to decrease strongly from 2564 to 886 μs when pressure is increased from ambient to 37.7 GPa. The pressure dependence of all the derived values of the present study is compared with Tb³⁺ in other glasses.     

Specific features of magneto-optical spectra of Tb<Subscript>3</Subscript>Ga<Subscript>5</Subscript>O<Subscript>12</Subscript>

The spectra of magnetic circular dichroism in the range of the ⁷ F ₆→⁵ D ₄ absorption band and the spectra of magnetic circular polarization of luminescence in the range of the ⁵ D ₄→⁷ F ₅ band in the terbium-gallium garnet Tb₃Ga₅O₁₂ are studied at a temperature of 80 K. The optical transitions between the Stark sublevels of the ⁷ F ₆, ⁷ F ₅, and ⁵ D ₄ multiplets are identified based on the analysis of the magneto-optical and optical spectra. It is shown that the experimentally determined symmetry and energy of the Stark sublevels of these multiplets confirm the results of numerical calculations of the energy spectrum of the Tb³⁺ rare-earth ion in terbium-gallium garnet.     

Excitation and luminescence of rare earth-doped lead phosphate glasses

Excitation and luminescence properties of Eu³⁺, Tb³⁺ and Er³⁺ ions in lead phosphate glasses have been studied. From excitation spectra of Eu³⁺ ions, the electron–phonon coupling strength and phonon energy of the glass host were calculated and compared to that obtained by Raman spectroscopy. Main intense and long-lived luminescence bands are related to the ⁵D₀–⁷F₂ (red) transition of Eu³⁺, the ⁵D₄–⁷F₅ (green) transition of Tb³⁺ and the ⁴I_13/2–⁴I_15/2 (near-infrared) transition of Er³⁺. The critical transfer distances, the donor–acceptor interaction parameters and the energy transfer probabilities were calculated using the fitting of the luminescence decay curves from ⁵D₀ (Eu³⁺), ⁵D₄ (Tb³⁺) and ⁴I_13/2 (Er³⁺) excited states. The energy transfer probabilities for Eu³⁺ (⁵D₀), Tb³⁺ (⁵D₄) and Er³⁺ (⁴I_13/2) are relatively small, which indicates low self-quenching luminescence of rare earth ions in lead phosphate glasses.     

Concentration-dependent luminescence of Tb ions in high calcium aluminosilicate glasses

This study deals with the results on the concentration-dependent fluorescence properties of Tb³⁺-doped calcium aluminosilicate (CAS) glasses of composition (100−x)(58SiO₂–23CaO–5Al₂O₃–4MgO–10NaF in mol%)-x Tb₂O₃ (x=0, 0.25, 0.5, 1, 2, 4, 8, 16, 24, 32, 40 in wt%). The FTIR reflectance spectra suggested the role of dopant ions as network modifiers in the glass network. The fluorescence spectra of low Tb³⁺-doped glasses have revealed prominent blue and green emissions from ⁵D₃ and ⁵D₄ excited levels to ⁷F_j ground state multiplet, respectively. The glass with 2 wt% of Tb₂O₃ has exhibited maximum intensity of blue emission from ⁵D₃ level, while green emission from ⁵D₄ level has increased linearly up to 24 wt% and showed reduction in the rate of increase for higher Tb₂O₃ concentrations. The concentration quenching of blue emission (⁵D₃→⁷F_j) is attributed mainly to the resonant energy transfer (RET) assisted cross-relaxation (CR) among the excited and nearest neighbour unexcited Tb³⁺ ions in the glass matrix. The decline in rate of increase of green emission (⁵D₄→⁷F_j) at higher concentrations has been explained due to a possible occurrence of cooperative energy transfers leading to 4f⁸→4f⁷5d transition interactions. The blue and green emission decay kinetics have been recorded to compute the excited level (⁵D₃ and ⁵D₄) lifetimes, which confirmed the Tb³⁺ concentration quenching of the blue emission in these glasses.     

Crystal-field analysis of Tb3+ doped yttrium aluminium garnet using site-selective polarized spectroscopy

The optical isotropy of the cubic garnet was overcome by crystal-site selective excitation and fluorescence spectroscopy. Thus the symmetries of the crystal-field states of the free ion levels⁷F _J and⁵D₄ could be determined. On this basis a crystal field analysis was performed to derive the crystal-field parameters for the Tb³⁺ ions replacing the Y³⁺ ions on the D₂ sites.     

Spectroscopic and magnetic susceptibility analyses of the FJ and D4 energy levels of Tb(4f) in TbAlO3

Detailed analyses of spectroscopic and temperature-dependent magnetic susceptibility data are reported for the crystal-field split energy levels of the ⁷F_J and ⁵D₄ of Tb³⁺ in stoichiometric single crystals of ortho-aluminate TbAlO₃. The spectroscopic data include absorption spectra obtained between 2940 and 480 nm from 8 to 300 K. High resolution fluorescence spectra are reported, representing transitions from ⁵D₄ to ⁷F_6,5,4, at a sample temperature of 85 K. Using crystal-field modeling techniques recently adapted for low symmetry systems, we have assigned all 58 experimental Stark levels within the ⁷F_J and ⁵D₄ manifolds, with a fitting standard deviation of 4.5 cm⁻¹ (3.8 cm⁻¹ rms error). As a further test, the theoretical Stark levels and calculated wavefunctions were used to determine the temperature dependence of the magnetic susceptibility along the c-axis of the TbAlO₃ crystal. Good agreement is obtained between the calculated susceptibility and temperature-dependent magnetic data reported earlier, including a prediction of a 0.2 cm⁻¹ splitting of the ground-state quasi-doublet. The susceptibility calculation also confirms the predicted ordering of states within the ⁷F₆ multiplet manifold.     

LnP5O14晶体中Tb3+和Eu3+的发光光谱特性

本工作测量了室温下TbP₃O₁₄和EuP₅O₁₄晶体的吸收和发射光谱。根据吸收光谱和Judd-Ofelt理论计算了Tb³⁺和Eu³⁺的实验和理论的振子强度。用最小二乘法拟合实验与理论的振子强度得到唯象强度参量Ω_λ。然后计算了Tb³⁺的⁵D₃→⁷F₅,⁵D₄→⁷F₄和⁵D₄→⁷F₆以及Eu³⁺的⁵D₀→⁷F₂,⁵D₀→⁷F₄的跃迁几率和寿命。同时用时间分辨光谱测量了不同温度下相应的荧光辐射寿命。计算与实验结果基本相符。理论和实验的结果表明Tb³⁺的⁵D₃态的寿命主要取决于⁵D₃→⁵D₄和⁷F₆→⁷F₀两能级对之间的电偶极-电偶极交叉弛豫。 关键词：     

Luminescence of CaWO4:Pr3+ and CaWO4:Tb3+ at ambient and high hydrostatic pressures

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 → ³H_J transitions in Pr³⁺ and the ⁵D₄ → ⁷F_J 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.     

Evaluation of the lanthanide compression by spectra of europium and terbium compounds

Comparison of the luminescence spectra of europium and terbium compounds was suggested for direct evaluation of the influence of compression of the lanthanide wavefunctions in transition from europium to terbium—‘lanthanide compression’. It is possible because the types of symmetry of the states of the Stark components of europium ⁷F_J energy levels determined previously could be used for assignment of corresponding components of Tb³⁺ energy levels. This procedure can lower the ambiguity of calculations of the crystal field parameters for terbium compounds.     

Vibronic and Raman spectra of Y(Eu3+) polytantalate, EuxY1?xTa7O19

Luminescence spectra, luminescence excitation spectra, and Raman spectra of polycrystalline Eu_0.9Y_0.1Ta₇O₁₉ were studied. Zero-phonon lines and vibronic sidebands of the ⁷ F ₀−⁵ D ₂ and ⁷ F ₀−⁵ D ₀ transitions were identified and the Stark splittings of several ⁷ F _J and ⁵ D _J , states of Eu³⁺ ions were investigated. The details of the structure of lanthanide polytantalates and the reduction of the luminescence quenching are discussed. Original Text ? Astro, Ltd., 2007.     

Low-temperature investigation of electronic excitations in wide-gap materials doped with RE3+ or Cr3+ ions

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.     

Solvent-Assisted Self-Quenching of the 5D3-State of Tb3+ in POCl3:SnCl4

The near infrared and visible spectra of Tb³⁺ in POCl₃:SnCl₄, in conjunction with the corresponding emission spectra, reveal an energy mismatch between the nonradiative transitions ⁵D₃ → ⁵D₄ and ⁷F₀ ← ⁷F₆ in favor of the former. This energy mismatch increases at higher temperatures. The temperature dependence of the self-quenching of the ⁵D₃-state of Tb³⁺, which requires the coupling between the aforementioned transitions, can be accounted for via a mode-assisted process.     

Spectral and luminescence properties of gadolinium gallium garnet epitaxial films doped with terbium

Gadolinium gallium garnet single-crystal films containing terbium are grown through liquid-phase epitaxy from a supercooled solution melt in the PbO-B₂O₃ system. The optical absorption spectra in the wavelength range 0.2–10.0 μm and the luminescence spectra excited by synchrotron radiation with energies in the range 3.5–30.0 eV are investigated at temperatures of 10 and 300 K. It is revealed that the optical absorption spectra contain an absorption band with the maximum at a wavelength λ ≈0.260 μm, which corresponds to the spin-allowed electric dipole transition between the electronic configurations 4f ⁸(⁷ F ₆) → 4f ⁷(⁸ S)5d of the Tb³⁺ ions. The narrow low-intensity absorption bands attributed to the 4f → 4f transitions from the ⁷ F ₆ ground level to the ⁷ F _0–5 multiplet levels of the Tb³⁺ ions are observed in the wavelength range 1.7–10.0 μm. In the luminescence spectra measured at a temperature of 10 K, the highest intensity is observed for a band with the maximum at a wavelength λ ≈ 0.544 μm, which is associated with the ⁵ D ₄ → ⁷ F ₅ radiative transition in the Tb³⁺ ion.     

Highly enhanced luminescence of Tb-activated gadolinium oxysulfide phosphor by doping with Zn ions

Gd₂O₂S:Tb phosphor were synthesized by co-precipitation method combined with solid-state reactions. The brightness of terbium-activated gadolinium oxysulfide phosphors were enhanced and size distributions were controlled by doping the phosphor with a specific amount of zinc oxide. By the analysis of X-ray diffractions, the excitation spectrum and emission spectrum, it can be confirmed that no new phase was introduced and lattice size was diminished. In this way, it may ease access to energy transfer between Gd³⁺ ions and Tb³⁺ ions as well as Tb³⁺ ions and Tb³⁺ ions. Therefore, self-sensitizations of Tb³⁺ ions can be enhanced, ⁵D₄-⁷F_J transitions were further improved and ⁵D₃-⁷F_J transitions were lowered. The enhancement of luminescent properties including brightness and chroma purity were also confirmed due to incorporations of Zn²⁺ ions.     

Facile synthesis and luminescence properties of uniform and monodisperse KY3F10:Ln3+ (Ln=Eu,Ce, Tb) nanospheres

Highly uniform and monodisperse KY₃F₁₀:Ln³⁺ (Ln=Eu, Ce, Tb) nanospheres, with an average diameter of 300 nm, have been successfully prepared through a simple template-free and surfactant-free stirring method under ambient conditions. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and photoluminescence (PL) spectra were used to characterize the samples. The SEM images illustrate that these spheres were actually composed of randomly aggregated nanoparticles. The doped rare earth ions show their characteristic emission in the KY₃F₁₀ samples, i.e., Eu^{3+ 5}D₀–⁷F_J (J=1, 2, 3, 4), Tb^{3+ 5}D₄–⁷F_J (J=6, 5, 4, 3, 2) and Ce³⁺ 5d–4f transition emissions, respectively. An energy transfer phenomenon from Ce³⁺ to Tb³⁺ has been observed in KY₃F₁₀ nanospheres, and the energy transfer efficiency depends on the doping concentration of Tb³⁺ if the concentration of Ce³⁺ is fixed.     

Synthesis and luminescence investigation of RE (Eu, Tb and Ce)-doped lithium silicate (Li2SiO3)

Synthesis and photoluminescence (PL) investigations of lithium metasilicate doped with Eu³⁺, Tb³⁺ and Ce³⁺ were carried out. PL spectra of Eu-doped sample showed peaks corresponding to the ⁵D₀→⁷F_j (j=1, 2, 3 and 4) transitions under ultraviolet excitation. Strong red emission coming from the hypersensitive ⁵D₀→⁷F₂ transition of Eu³⁺ ion suggested the presence of the dopant ion in structurally disordered environment. Tb³⁺-doped silicate sample showed blue-green emission corresponding to the ⁵D₄→⁷F_j (j=6, 5 and 4) transitions. Ce-doped sample under excitation from UV, showed a broad emission band in the region 350-370 nm with shoulders around 410 nm. The fluorescence lifetimes of Eu³⁺ and Tb³⁺ ions were found out to be 790 and 600 μs, respectively. For Ce³⁺, the lifetime was of the order of 45 ns. PL spectra of the europium- and terbium-doped samples were compared with commercial red (Y₂O₃:Eu³⁺) and green (LaPO₄:Tb³⁺) phosphors, respectively. It was found that the emission from the doped silicate sample was 37% of the commercial phosphor in case of the Tb-doped sample and 8% of the commercial phosphor in case of the Eu-doped sample.