Function Of Tb3 Research Articles

Evaluating the link between blue-green luminescence and cross-relaxation processes in Tb3+-doped glasses

In this study, luminescence properties of Tb3+-doped low silica calcium aluminosilicate glasses are analyzed as a function of Tb3+ concentration (0.04–15.0 wt%). Decay curves for the 5D3 level are found to be non-exponential for all Tb3+ concentrations due to ion–ion energy transfer through cross-relaxation process. To identify the origin of the energy transfer mechanism, the decay curves were well fitted by Inokuti–Hirayama model (s = 6), which indicates that the energy transfer process is related to dipole–dipole interaction. Trivalent Tb-doped materials normally exhibit stronger green emission compared to blue emission, a feature that increases with Tb3+ concentration and is attributed to the cross-relaxation process. In this paper, we show a remarkable blue emission in comparison to other Tb3+-doped glasses. A theoretical model for the blue and green emissions, from 5D3 and 5D4 levels respectively, was proposed to establishing a link between the color emission and the 5D3 lifetime quenching due to a cross-relaxation process. This model was successfully applied to the experimental results of this paper as well as previous data in the literature.

Luminescent properties of terbium doped barium hafnate perovskite: Synthesis and characterization

This contribution exhibits the luminescence properties of BaHfO3: Tb3+ perovskite ceramics. The main objective is to know the effect on the luminescent properties of the trivalent Terbium ion (Tb3+), when it is introduced into a crystalline structure of high symmetry such as perovskite, where it can occupy any of two sites available in the lattice. The synthesis of these nanocrystal powders was conducted by hydrothermal route. X-ray diffraction pattern showed crystallized cubic perovskite type structure with space group Pm-3m. Luminescence spectra showed emission peaks which are associated to the 5D4→7FJ (J = 2, 3, 4, 5, 6) typical transitions of trivalent terbium ion. Photoluminescence features were obtained as a function of Tb3+ doping concentration, being the sample doped with Tb3+ (5 at.%) the one presented the highest intensity peak emission. Also, some characteristics of the decay time, surface morphology, crystallite size and chemical composition of the studied powders, are shown.

Generating green and yellow lines in Y6Si3O9N4:Ce3+,Tb3+/Dy3+ oxynitrides phosphor

Tb3+/Dy3+ co-doped Y6Si3O9N4:Ce3+ oxynitride phosphors were prepared in this work. The properties of the prepared phosphors, e.g. X-ray diffraction (XRD), photoluminescence (PL) spectra, lifetime and thermal-dependent luminescence quenching were investigated systematically. Under near-UV excitation, co-doped Tb3+ and Dy3+ into Y6Si3O9N4:Ce3+ phosphor generated a narrow green line peaked at 550 nm and a yellow line peaked at 575 nm, respectively. Energy is efficiently transferred from Ce3+ to Dy3+ and Tb3+ ions according to the study results. Fluorescence decay patterns are studied as a function of Tb3+ and Dy3+ concentrations. For the new synthesized phosphors, their temperature-dependent photoluminescence properties were investigated, which demonstrates that the emission intensity at 150 ○C reduced from 100% to 32.0% measured at 30○C. Commission on illumination value of color tumble emission is also discussed in detail. This work verifies the suitable application of the new oxynitride phosphor in the LEDs.

Tunable Luminescence and Energy Transfer in Novel Blue-Green-Emitting BaGd2Si3O10:Ce3+,Tb3+ Phosphors for Near-UV-Based White LEDs

A new series of Ce3+ singly doped and Ce3+/Tb3+-co-doped BaGd2Si3O10 (BGSO) phosphors have been synthesized by a high-temperature solid-state reaction technique. The phase purity, luminescence properties, energy transfer mechanism, internal quantum efficiency, and thermal stability of as-prepared phosphors were investigated in detail. The photoluminescence spectra of BGSO:xCe3+ phosphors exhibited broad emission in the wavelength range of 350–600 nm with a peak maximum at 427 nm. Under 336 nm excitation, the tunable blue-green luminescence of BGSO:0.04Ce3+,yTb3+ phosphors was investigated as a function of Tb3+ concentration and well demonstrated by the energy transfer mechanism from Ce3+ to Tb3+ ions. The critical distance (Rc) of energy transfer was estimated using concentration quenching method, and its value was found to be 10.75 A. The thermal stability and activation energy of thermal quenching were analyzed for composition-optimized BGSO:0.04Ce3+,0.30Tb3+ phosphors by varying the temperature from 30...

Effect of Tb3+ concentration in the visible emission of terbium-doped gadolinium oxysulfide microspheres

Experimental data obtained from optical characterization of Gd2O2S:Tb3+ microspheres were compared with a rate-equation model in order to understand and simulate the emission intensity and color tonality as a function of Tb3+ concentration. The microparticles were prepared by hydrothermal synthesis and characterized by TEM and XRD to confirm spherical microparticles with a hexagonal lattice. Furthermore, fluorescent spectroscopy and rate equation model revealed that the direct energy transfer between Gd3+→Tb3+ ions and the migration of the excitation energy between Tb3+ play an important role in the luminescence intensity, while the color tonality is mainly governed by the non-radiative relaxation processes between Tb3+ at low concentrations. Finally, our results suggest that the rate equation model provides an efficient alternative to estimate theoretically the maximum doping concentration in oxysulfides before they present quenching of luminescence.

Luminescent properties of Tb3+- doped TeO2-WO3-GeO2 glasses for green laser applications

Different concentrations of Tb3+ -doped oxyfluoro tellurite (TWGTb) glasses were prepared by conventional melt quenching technique and characterized for green laser applications. The Judd-Ofelt theory was applied to evaluate various spectroscopic and radiative parameters. The TWGTb glasses exhibit 5D3 → 7F5-3 and 5D4 → 7F6-0 transitions when excited at 316 nm radiation. The variation of intensity of 5D4 → 7F5 (Green) and 5D3 → 7F4 (Blue) transitions and the green to blue (IG/IB) intensity ratios were studied as a function of Tb3+ ions concentration. The laser characteristic parameters such as effective bandwidth (Δλeff), stimulated emission cross-section (σe), gain bandwidth (σe × Δλeff) and optical gain (σe × τR) were determined using the three phenomenological Judd-Ofelt intensity parameters. The fluorescence decay profiles of 5D4 metastable level exhibit single-exponential nature for all the samples. Based on the experimental results we suggest that the 1.0 mol% of Tb3+ -doped TWGTb glass could be a suitable laser host material to emit intense green luminescence at 545 nm.

Luminescence and decay characteristics of Tb3+-doped fluorophosphate glasses

ABSTRACTTb3+-doped fluorophosphate glasses with the composition of P2O5–K2O–SrF2–Al2O3–x Tb4O7 (where x = 0.1, 0.5, 1.0, 2.0 and 4.0 mol%) were prepared by a conventional high temperature melt quenching technique and characterized through absorption, emission, excitation and decay measurements. From the emission studies, a strong green emission at around 546 was observed, which corresponds to the 5D4 → 7F5 transition of Tb3+ ion. Green/blue intensity ratios (IG/IB) were evaluated as a function of Tb3+ concentration and vice versa. Higher IG/IB intensity ratio confirms the higher covalency between Tb–O bond and higher asymmetry around the Tb3+ ions in the present fluorophosphate glasses. The decay curves for the 5D4 level of Tb3+ ion were measured and found that they exhibited single exponential nature irrespective to the dopant concentration. The experimental lifetime was determined using single exponential fitting and found that it increased from 2.65 to 2.95 ms when Tb3+ concentration increased from 0.1 mol% to 4.0 mol%. The derived properties were compared to the other Tb3+-doped glasses in order to see the potentiality of the material for visible laser gain media at 546 nm.

Photoluminescence and energy transfer behavior of narrow band red light emitting Li3Ba2Tb3(MoO4)8:Eu3.

This work concerns the polycrystalline red emitting solid state compound Li3Ba2(Tb1-xEux)3(MoO4)8, from which a series of powder samples was prepared by a conventional solid-state reaction. The phase formation of the samples was investigated by X-ray diffraction which revealed the formation of a solid solution without a miscibility gap. Photoluminescence (PL) spectra and decay curves were recorded as a function of Tb3+ and Eu3+ concentration and temperature. It turned out that the external quantum efficiency of Eu3+ photoluminescence is between 30 and 80%, while the highest quantum yield is achieved for about 60% Tb3+. An increase of emission intensity can be realized by co-doping of Eu3+ and Tb3+. Moreover, the emission has a luminous efficacy of 275 lm Wopt-1 which is a distinct advantage over the widely applied Mn4+ activated fluorides. The time dependent photoluminescence as a function of Tb3+ concentration demonstrates the presence of an efficient energy transfer from Tb3+ to Eu3+. Temperature dependent PL measurements revealed that Li3Ba2(Tb1-xEux)3(MoO4)8 loses just 20% of PL efficiency up to 400 K. Therefore, the investigated phosphors are attractive for application in pcLEDs. It is finally demonstrated that the application of a Eu3+/Tb3+ co-doped ceramic disc is useful for the colour conversion of a blue emitting LED with a higher conversion rate compared to Li3Ba2(La1-xEux)3(MoO4)8.

Visible luminescence from highly textured Tb3+ doped RF sputtered zinc oxide films

Highly transparent, luminescent, c-axis oriented Tb3+ doped ZnO films are prepared by RF magnetron sputtering technique. The structural, morphological, optical and luminescence properties of these films are investigated as a function of Tb3+ doping concentration by X-ray diffraction (XRD), micro-Raman spectroscopy, atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM), spectroscopic ellipsometry, UV-Visible spectroscopy and photoluminescence spectroscopy. The as-deposited films are found to be highly crystalline with wurtzite hexagonal phase of ZnO. The characteristic features of hexagonal wurtzite structure of ZnO, particularly the appearance of non-polar E2 modes are easily identified from the Raman spectra of the films. The surface morphology of the films revealed by FESEM and AFM images present a dense distribution of grains. The elemental analysis carried out using energy dispersive X-ray (EDX) spectra confirms the incorporation of Tb3+ ions in the ZnO lattice. The films are highly transparent in the visible region. Using ellipsometric analysis, the variation of refractive index, dielectric constant and thickness of the films are studied as a function of Tb3+ doping concentration. The photoluminescence spectra of the Tb3+ doped ZnO films recorded using an excitation radiation of wavelength 325nm from a He-Cd laser exhibit visible luminescence ~430, 490, 516 and 542nm. The origin of visible emissions ~490 and 542nm in the doped films can be attributed to 5D4→7F6 and 5D4→7F5 transition of Tb3+ ion respectively. The intensity of the emission at 542nm is found to be decreasing at higher doping concentration due to concentration quenching effect. The blue emission in the films can be attributed to the electron transition from shallow donor level formed by interstitial Zn atoms to the top of the valence band. The origin of the visible emission ~516nm is attributed to antisite oxygen defects in ZnO.

Luminescence properties of Tb3+-doped zinc phosphate glasses for green laser application

Tb3+-doped zinc phosphate glasses of composition in mol%: (100.0 − x)Zn(PO3)2 – xTb2O3, x = 0.6, 1.0, 2.0 and 5.0, were prepared by conventional melt quenching technique and characterized by photoluminescence and decay time spectroscopy. The integrated intensities of the 5D4 → 7F5 (green at 541 nm) and 5D3 → 7F4 (blue at 435 nm) emissions and their intensity ratios IG/IB upon 350 nm excitation have been evaluated as function of Tb3+ concentration. The CIE1931 color of the glasses excited at 350 nm varies from turquoise to green by increasing the Tb3+ content. The increased IG/IB ratio up to a factor of 364 for the phosphor with the highest Tb3+ content (ZP5Tb) is consistent with the observed shift toward the green region in the CIE coordinates, so that the ZP5Tb glass exhibits a green color purity of 66.9% with chromaticity coordinates (0.290, 0.581), being very close to those (0.29, 0.60) of European Broadcasting Union illuminant green. This interesting feature of the ZP5Tb phosphor, together with an experimental branching ratio larger than 60% of the 5D4 → 7F5 green emission, highlights its capability as solid state green laser pumped by AlGaN (350 nm) LEDs. The decay time profiles of the 5D3 level resulted to be non-exponential for all the studied concentrations due to energy transfer between Tb3+ ions through cross-relaxation. Such decay profiles were well fitted to the Inokuti–Hirayama model for S = 6, which indicates that an electric dipole-dipole interaction might be the dominant mechanism in the cross-relaxation energy transfer occurring in Tb3+ ion clusters.

Optical band gap and photoluminescence in heavily Tb3+ doped GeO2-B2O3-SiO2-Ga2O3 magneto-optical glasses

In this study, germanium borosilicate magneto-optical (MO) glasses (GeO2-B2O3-SiO2-Ga2O3-xTb2O3) doped with different concentrations of Tb3+ ions were prepared by melt quenching technique. Structural, physical properties, optical properties and luminescent properties of obtained glasses were investigated in detail. Raman spectrum of the MO glasses shows that co-existence of trigonal [BO3], tetrahedral [BO4] and [GeO4] units were the main network structure and the increasing of Tb2O3 in glass promoted the conversion of BO3 into BO4. The aforementioned structural change observed in MO glasses as a function of Tb3+ ion concentration is reflected by the increase of glass density and decrease of molar volume. The obtained MO glasses exhibits a large of Verdet constant (at 632.8 nm) ranging from −49.98 to −120.54 Rad/T/m in a positive correlation with Tb3+ ion concentration. The value of Urbach energy (ΔE) and optical band gap (Eobg) shows a negative correlation with Tb3+ ion concentration. The luminescent intensity in 5D4 fluorescent level decreases with the increase of Tb3+ ions concentration, and the concentration quenching is found when changing the content of Tb2O3 from 15 mol% to 30 mol%.

Luminescent Characteristics of Ba(1--x)Al2Si2O8:xTb3+ Green Phosphors.

Ba(1--x)Al2Si2O8:xTb3+ (0.03 < or = x < or = 0.12) green phosphors are prepared by solution combustion method. The photoluminescence properties of the Ba(1--x)Al2Si2O8:xTb3+ phosphors are studied as a function of Tb3+ concentration. The Ba(1--x)Al2Si2O8:xTb3+ phosphors crystallize in a hexagonal crystal structure. The excitation spectra consist of two broad bands with maxima at 238 nm and 265 nm and several weak peaks in the range of 310-500 nm. Strong emission peaks are observed at 484, 540, 589, and 612 nm due to the (5)D4 --> (7)F6, (5)D4 --> (7)F5, (5)D4 --> (7)F4, and (5)D4 --> (7)F3 tran- sitions of the Tb3+, respectively. The emission peak (540 nm) from the (5)D4 --> (7)F3 transition is dominant, indicating green light emission. Ba(1--x)Al2Si2O8:xTb3+ phosphor shows the strongest green emission intensity. The Ba(1--x)Al2Si2O8:xTb3+ can be considered a promising green phosphor for white LEDs applications.

Luminescence properties of Tb3+ ions in zinc fluorophosphate glasses for green laser applications

Tb3+-doped zinc fluorophosphate glasses of composition (in mol.%): 44 P2O5+17K2O+9 Al2O3+(29−x) ZnF2+x Tb4O7, x=0.1, 0.5, 1.0 and 2.0, have been prepared by conventional melt quenching technique. The absorption, luminescence and decay curves of these glasses have been studied. The luminescence spectra of Tb3+ ions exhibit its characteristic 5D4→7FJ (J=3, 4, 5 and 6) and 5D3 →7FJ (J=3, 4 and 5) transitions under 376nm excitation. The integrated intensities of the 5D4→7F5 (green at 546nm) and 5D3→7F4 (blue at 439nm) transitions and their intensity ratios (IG/IB) have been evaluated as function of Tb3+ ion concentration. Decay curves have been measured for the 5D3 and 5D4 levels of Tb3+ ion in these glasses and lifetime has been determined and discussed with the other Tb3+-reported glasses.

Synthesis and characteristics of pure β-Ga2O3 and Tb3+ doped β-Ga2O3 hollow nanostructures

The pure β-Ga2O3 and Tb3+ doped β-Ga2O3 hollow nanostructures with various Tb3+ concentrations were prepared by hydrothermal and cacination processes. The X-ray diffraction patterns indicate that the core-shell structures are amorphous phase before calcination and perfectly crystallized β-Ga2O3 hollow nanostructures were obtained at 800°C. The sharp and intense band absorption at 1384cm−1, which was attributed to the Ga(OH)CO3 shell, was observed by Fourier transform infrared. Field-emission scanning electron microscopy and high-resolution transmission electron microscopy investigations showed β-Ga2O3 hollow nanostructures with diameters of about 200nm and thicknesses of about 20~30nm. The green emission spectra of Tb3+ doped β-Ga2O3 hollow nanostructures as a function of Tb3+ ions were observed due to the 5D4→7FJ transition. The Tb3+-doped β-Ga2O3 hollow nanostructures showed the highest green emission intensity at 7mol% of Tb3+ ions.

Effects of the host lattice and doping concentration on the colour of Tb3+ cation emission in Y2O2S:Tb3+ and Gd2O2S:Tb3+ nanometer sized phosphor particles

Y2O2S and Gd2O2S phosphor lattices activated with a range of Tb(3+) concentrations have been successfully prepared as nanoparticles and their emission properties have been characterized using SEM, XRPD, photoluminescence spectroscopy and cathodoluminescence. (5)D3-(5)D4 cross relaxation processes between Tb(3+) cations were observed in both Y2O2S and Gd2O2S as a function of Tb(3+) concentration. In the Y2O2S host lattice, the predominant emission colour shifts from blue to green with increased Tb(3+) concentration. In contrast, green emission is always predominant in Gd2O2S at Tb(3+) concentrations from 0.1 mol% to 5 mol%. This finding is explained in accordance with previous reports on the bulk materials that found the Gd2O2S lattice has a lower charge transfer state than the Y2O2S host lattice.

Luminescent properties of Gd3+ sensitized low-phonon energy CaGd4O7:Tb3+ green emitting novel phosphors

The trivalent terbium (Tb3+) ions activated CaGd4O7 (CG) phosphors were synthesized by a sol–gel method. The characterizations were performed after the samples annealed at 1500°C. The structural and morphological properties were analyzed from the X-ray diffraction patterns and scanning electron microscope images. The photoluminescence excitation spectra showed a broad-band between the wavelengths 250 and 300nm, which were overlapped with the Gd3+ excitation bands. The photoluminescence spectra exhibited efficient green emission due to the sensitization effect of Gd3+ ions on the Tb3+ ions when exciting with the Gd3+ wavelength at 278nm. In order to analyze the influence of Tb3+ concentration on the luminescence behavior of Tb3+ ions in the CG host lattice, the decay curves were measured. The temperature-dependent luminescence measurements were done to identify the thermal stability of CG:Tb3+ phosphors at elevated temperatures. The cathodoluminescent spectra also showed a similar behavior to that observed in PL spectra. The CIE chromaticity coordinates as a function of Tb3+ concentration were calculated and all the obtained chromaticity coordinates have been placed in the green spectral region.

Luminescent properties of SrSi2N2O2:Ce3+,Tb3+—a potential phosphor for white light emitting diodes

Ce3+ and Tb3+ co-doped SrSi2N2O2 phosphors were prepared by solid-state reaction. The X-ray diffraction pattern exhibited that the phosphor consisted mainly of oxygen-rich SrSi2N2O2. The optical properties of SrSi2N2O2:Ce3+, SrSi2N2O2:Tb3+ and SrSi2N2O2:Ce3+,Tb3+ were studied, respectively. The emission intensity of Tb3+ at 541 nm was remarkably enhanced by Ce3+ in SrSi2N2O2:Ce3+,Tb3+ phosphor, which was attributed to the energy transfer from Ce3+ to Tb3+. The chromaticity coordinates of phosphors were investigated as a function of Tb3+ concentration. When the Ce3+ and Tb3+ concentrations were 0.02 and 0.18 mol per formula unit, respectively, the chromaticity coordinate was (0.257, 0.337) in the CIE 1931 chromaticity diagram. SrSi2N2O2Ce3+,Tb3+ phosphors could be used for white light emitting diodes.

Transition from Long-Range to Short-Range Energy Transfer through Donor Migration in Garnet Hosts

We demonstrate that the mechanism for nonradiative energy transfer, a critical aspect in many optical systems, can switch from a longer-range dipole−dipole mechanism to a short-range exchange mechanism through energy migration between donors. This transition significantly increases energy transfer rates and is analyzed using measurements of Tb3+(5D4)→Ce3+(5d1) energy transfer as a function of Tb3+ concentration in (Lu,Tb)3Al5O12:Ce3+ garnet phosphors. The additional short-range energy transfer is assigned to exchange by the analysis of the migration and trapping rates as well as estimates of the relevant exchange integrals.

Matrix induced synthesis of LaNbO4:Tb3+ phosphors by in situ composing hybrid precursors

Abstract In this paper, a novel modified in situ chemical coprecipitation technology was achieved to synthesize LaNbO4 doped with Tb3+ phosphors. Among rare earth (La and Tb) coordination polymers were adopted as precursors for the La and Tb oxides sources, and polyethylene glycol (PEG) was introduced to form the hybrid polymeric systems with rare earth coordination polymers. Accompanied with other functional components, the multicomponent hybrid precursors were composed by an in situ coprecipitation process. After the calcination, LaNbO4:Tb3+ phosphors were obtained, whose particle sizes were in the range of 1–3 μm characterized by XRD and SEM. The photoluminescence properties of LaNbO4:Tb3+ phosphors were compared to investigate as a function of Tb3+ ion concentrations, which revealed that these nanophosphors showed a strong visible green emission from 5D4 to 7F5 at 543 nm under ultraviolet excitation. The luminescence of Tb3+ quenches emission for a charge-transfer-band of NbO 4 3 - .

Matrix-inducing synthesis and luminescence of novel unexpected coral-like morphology Mg2Gd8(SiO4)6O2:Tb3+ nanophosphor from in situ composing multicomponent hybrid precursors

Mg2Gd8(SiO4)6O2 doped with Tb3+ was in situ synthesized by a novel hybrid precursors assembly sol–gel technology. The particle size of luminescent materials is in the range of 60–100 nm characterized by XRD and especially SEM shows that there exist some novel unexpected morphological structures owing to multicomponent hybrid precursors. The photoluminescence property of Mg2Gd8(SiO4)6O2:Tb3+ was compared to investigate as a function of Tb3+ ions concentration, which revealed that these nanophosphors showed a strong green emission from 5D4 to 7F5 at 543 nm.