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1.
Chitosan membranes with trivalent lanthanide ion Eu3 + were prepared at a ratio of 3:1 w/w (chitosan:lanthanide). There was no membrane formation at a ratio of 1:1 w/w (chitosan: Eu3 + or Tb3 +); in this case a white solid powder was obtained. Both chitosan compounds were characterized by elemental analysis (CHN), thermal analysis (TG/DTG), scanning electron microscopy (SEM) and luminescence spectroscopy. CHN analysis was performed only for chitosan compounds in powder form, suggesting that these compounds have the general formula QUILn.6H2O, where QUI = Chitosan and Ln = Eu3 + or Tb3 +. The results of TG/DTG curves for chitosan membranes with Eu3 + ion indicate that the introduction of this metal into the chitosan structure causes gradual degradation in residual carbons, showing lower weight loss in the Eu3 + membranes compared to pure chitosan membrane. Analysis of luminescence demonstrated that chitosan membranes with Eu3 + ion exhibit emission in the visible region, showing emission bands from chitosan and Eu3 + moieties. For chitosan with Eu3 + and Tb3 + ions compounds, in powder form, the analysis of luminescence suggested that chitosan is not transferring energy to the lanthanide ion; however, the chemical region where the lanthanide ion is found breaks the selection rules and favors the emission of these ions.  相似文献   

2.
Four kinds of luminescent hybrid soft gels have been assembled by introducing the lanthanide (Eu3+, Tb3+) tetrakis β‐diketonate into the covalently bonded imidazolium‐based silica through electrostatic interactions. Here, the imidazolium‐based silica matrices are prepared from imidazolium‐derived organotriethoxysilanes by the sol–gel process, in which the imidazolium cations are strongly anchored within the silica matrices while anions can still be exchanged following application for functionalization of lanthanide complexes. The photoluminescence measurements indicated that these hybrid soft gels exhibit characteristic red and green luminescence originating from the corresponding ternary lanthanide ions (Eu3+, Tb3+). Further investigation of photophysical properties reveals that these soft gels have inherited the outstanding luminescent properties from the lanthanide tetrakis β‐diketonate complexes such as strong luminescence intensities, long lifetimes and high luminescence quantum efficiencies.  相似文献   

3.
A series of Eu3+ ions co-doped (Gd0.9Y0.1)3Al5O12:Bi3+, Tb3+ (GYAG) phosphors have been synthesized by means of solvothermal reaction method. The XRD pattern of GYAG phosphor sintered at 1500 °C confirms their garnet phase. The luminescence properties of these phosphors have been explored by analyzing their excitation and emission spectra along with their decay curves. The excitation spectra of the GYAG:Bi3+, Tb3+, Eu3+ phosphors consists of broad bands in the shorter wavelength region due to 4f8 → 4f75d1 transition of Tb3+ ions overlapped with 6s2 → 6s16p1 (1S0 → 3P1) transition of Bi3+ ions and the charge transfer band of Eu3+–O2?. The present phosphors exhibit green and red colors due to 5D4 → 7F5 transition of Tb3+ ions and 5D0 → 7F1 transition of Eu3+ ions, respectively. The emission was shifted from green to red color by co-doping with Eu3+ ions, which indicate that the energy transfer probability from Tb3+ to Eu3+ ions are dependent strongly on the concentration of Eu3+ ions.  相似文献   

4.
A series of phosphors SrBPO5:R,Na+ (R = Eu3+, Tb3+) were prepared by high-temperature solid-state synthesis, and their phase purity, morphology, IR spectra, and UV-Vis photoluminescence properties were investigated. The f-f transitions of Eu3+ and Tb3+ ions in the host lattice were assigned and discussed. The excitation and emission spectra indicate that SrBPO5:Eu3+,Na+ and SrBPO5:Tb3+,Na+ can be effectively excited by ultraviolet (394 and 370 nm), and exhibit reddish orange emission and yellowish green emission, respectively. The influence of the doping concentration on the relative emission intensity of Eu3+/Tb3+ was investigated, and the critical distance Rc was estimated in term of the concentration quenching data. The present study suggests SrBPO5:R,Na+ (R = Eu3+, Tb3+) phosphor can be a potential candidate as an UV-convertible phosphor for white light-emitting diodes (LEDs).  相似文献   

5.
Developing multiplex sensing technique is of great significance for fast sample analysis. However, the broad emissions of most chemiluminescence(CL) luminophores make the multiplex CL analysis be difficult. In this work, a simple and sensitive CL analytical method has been developed for the simultaneous determination of Tb3+and Eu3+thanking to their narrow band emission. The technique was based on a mixed CL system of periodate(IO4-)-hydrogen peroxide(...  相似文献   

6.
The photoluminescence (PL) studies on NaIn1?xRExW2O8, with RE=Eu3+, Tb3+, Dy3+ and Tm3+ phases have shown that the relative contribution of the host lattice and of the intra-f–f emission of the activators to the PL varies with the nature of the rare earth cation. In the case of Dy3+ and Tm3+ activators, with yellow and blue emission, respectively, the energy transfer from host to the activator plays a major role. In contrast for Eu3+, with intense red emission, the host absorption is less pronounced and the intra-f–f transitions of the Eu3+ ions play a major role, whereas for Tb3+ intra-f–f transitions are only observed, giving rise to green emission.  相似文献   

7.
The polychromatic emission and wide-range color tuning in the luminescent nanoparticles are currently of crucial importance, due to the development of color and white light-emitting diode (LED) devices, based on such lanthanide-doped nanostructured materials. By utilization of precipitation method, Tb3+-doped and Tb3+/Eu3+-codoped NaYbF4 nanoparticles (i.e. NPs) are synthesized. For Tb3+-doped NaYbF4 NPs excited by 377 nm, green emission originating from Tb3+ is observed, where its optimum state is obtained when Tb3+ content is 25 mol% and the concentration quenching mechanism is found by electric dipole-dipole interaction. Moreover, due to the existence of energy transfer between Tb3+ and Eu3+, polychromatic emissions are realized in Tb3+/Eu3+-codoped NaYbF4 NPs as Eu3+ content increases. Through analyzing emission decay times and emission spectra, it was confirmed that the energy transfer mechanism in the synthesized NPs is governed mainly by electric dipole-dipole interaction. Furthermore, the resultant NPs also own strong resistance to temperature, which is verified by temperature-dependent emission spectra, and the activation energies of Tb3+ and Eu3+ are 0.206 and 0.207 eV, respectively. In addition, by employing designed NPs as yellow-emitting components, the fabricated white-LED emits brightness warm white light with color coordinate of (0.385, 0.380), high color rendering index of 84.3 and low correlated color temperature of 3903 K. This work does not only offer an available route to develop NPs with polychromatic emissions but also devise promising luminescent materials for improving the performance of the phosphor-converted white-LED.  相似文献   

8.
In this work, a latent energy-transfer process in traditional Eu3+,Tb3+-doped phosphors is proposed and a new class of Eu3+,Tb3+-doped Na4CaSi3O9 (NCSO) phosphors is presented which is enabled by luminescence decay dynamics that optimize the electron-transfer energy process. Relative to other Eu3+,Tb3+-doped phosphors, the as-synthesized Eu3+,Tb3+-doped NCSO phosphors show improved large-scale tunable emission color from green to red upon UV excitation, controlled by the Tb3+/Eu3+ doping ratio. Detailed spectroscopic measurements in the vacuum ultraviolet (VUV)/UV/Vis region were used to determine the Eu3+–O2− charge-transfer energy, 4f–5d transition energies, and the energies of 4f excited multiplets of Eu3+ and Tb3+ with different 4fN electronic configurations. The Tb3+→Eu3+ energy-transfer pathway in the co-doped sample was systematically investigated, by employing luminescence decay dynamics analysis to elucidate the relevant energy-transfer mechanism in combination with the appropriate model simulation. To demonstrate their application potential, a prototype white-light-emitting diode (WLED) device was successfully fabricated by using the yellow luminescence NCSO:0.03Tb3+, 0.05Eu3+ phosphor with high thermal stability and a BaMgAl10O17:Eu2+ phosphor in combination with a near-UV chip. These findings open up a new avenue to realize and develop multifunctional high-performance phosphors by manipulating the energy-transfer process for practical applications.  相似文献   

9.
Three novel lanthanide complexes with the ligand 4,4-difluoro-1-(1,5-dimethyl-1H-pyrazol-4-yl)butane-1,3-dione (HL), namely [LnL3(H2O)2], Ln = Eu, Gd and Tb, were synthesized, and, according to single-crystal X-ray diffraction, are isostructural. The photoluminescent properties of these compounds, as well as of three series of mixed metal complexes [EuxTb1-xL3(H2O)2] (EuxTb1-xL3), [EuxGd1-xL3(H2O)2] (EuxGd1-xL3), and [GdxTb1-xL3(H2O)2] (GdxTb1-xL3), were studied. The EuxTb1-xL3 complexes exhibit the simultaneous emission of both Eu3+ and Tb3+ ions, and the luminescence color rapidly changes from green to red upon introducing even a small fraction of Eu3+. A detailed analysis of the luminescence decay made it possible to determine the observed radiative lifetimes of Tb3+ and Eu3+ and estimate the rate of excitation energy transfer between these ions. For this task, a simple approximation function was proposed. The values of the energy transfer rates determined independently from the luminescence decays of terbium(III) and europium(III) ions show a good correlation.  相似文献   

10.
Excitation of Tb3+ and Eu3+ in DMSO with 487 mμ, which corresponds to the 7F65D4 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.  相似文献   

11.
We present an efficient way to search a host for ultraviolet (UV) phosphor from UV nonlinear optical (NLO) materials. With the guidance, Na3La2(BO3)3 (NLBO), as a promising NLO material with a broad transparency range and high damage threshold, was adopted as a host material for the first time. The lanthanide ions (Tb3+ and Eu3+)-doped NLBO phosphors have been synthesized by solid-state reaction. Luminescent properties of the Ln-doped (Ln=Tb3+, Eu3+) sodium lanthanum borate were investigated under UV ray excitation. The emission spectrum was employed to probe the local environments of Eu3+ ions in NLBO crystal. For red phosphor, NLBO:Eu, the measured dominating emission peak was at 613 nm, which is attributed to 5D0-7F2 transition of Eu3+. The luminescence indicates that the local symmetry of Eu3+ in NLBO crystal lattice has no inversion center. Optimum Eu3+ concentration of NLBO:Eu3+ under UV excitation with 395 nm wavelength is about 30 mol%. The green phosphor, NLBO:Tb, showed bright green emission at 543 with 252 nm excited light. The measured concentration quenching curve demonstrated that the maximum concentration of Tb3+ in NLBO was about 20%. The luminescence mechanism of Ln-doped NLBO (Tb3+ and Eu3+) was analyzed. The relative high quenching concentration was also discussed.  相似文献   

12.
Cooperative performance of mixed‐valent Eu2+/Eu3+ in single‐compound phosphors offers significant advantages in color rendering and luminescence efficiency, but their synthesis is challenging because of Eu2+ oxidation. Using the tunable nature of the metal‐ion nodes in metal–organic frameworks (MOFs), we present an in situ reduction and crystallization route for preparing MOFs and doping Eu2+/Eu3+ with a controlled ratio. These materials exhibit rich photoluminescence, including intrinsic‐ and sensitized‐emissions of Eu2+ and Eu3+, and long‐lived luminescence from charge transfer. Color rendering can be easily achieved by fine‐tuning the valence states of Eu. A linear relation between temperature and the intensity ratio of Eu2+/Eu3+ emissions provides outstanding properties for applications as self‐calibrated luminescent thermometers with a wide working temperature range. Further incorporation of Tb3+ into the MOFs results in white light, utilizing all Eu2+,Tb3+, and Eu3+ emissions in a single crystalline lattice.  相似文献   

13.
New LnxBi2–xSe3 (Ln: Sm3+, Eu3+, Gd3+, Tb3+) based nanomaterials were synthesized by a co‐reduction method. Powder XRD patterns indicate that the LnxBi2–xSe3 crystals (Ln = Sm3+, Eu3+, x = 0.00–0.44 and Ln = Gd3+, Tb3+, x = 0.00–0.50) are isostructural with Bi2Se3. The cell parameter c decreases for Ln = Eu3+, Gd3+, Tb3+ upon increasing the dopant content (x), while a slightly increases. Changes in lattice parameters could be related to the radii of cations. SEM images show that doping of the lanthanide ions in the lattice of Bi2Se3 generally results in nanoflowers. For the terbium compound two kinds of morphologies (nanoflowers and nanobelts) were observed. UV/Vis absorption and emission spectroscopy reveals mainly electronic transitions of the Ln3+ ions. Emission spectra show intense transitions from the excited to the ground state of Ln3+ and energy transfer from the Bi2Se3 lattice. Emission spectra of europium‐doped materials, in addition to the characteristic red emission peaks of Eu3+, show an intense blue emission band centered at 432 nm, originating from the 4f65d1 to 4f7 configuration in Eu2+. EPR measurements confirm the existence of Eu2+ in the materials. Interestingly, for all samples starting at low Ln3+ concentration, the emission intensity rises to a maximum at a Ln3+ concentration of x = 0.2 and falls again steadily to a minimum at x = 0.45.  相似文献   

14.
The effects of the stop band (SB) in colloidal photonic crystals composed of silica spheres containing Eu3+‐ and Tb3+‐doped yttria nanoparticles are analysed. Reflection and transmission spectra indicate movement of the stop band, due to the 111 series of planes, towards shorter wavelengths with increasing angle of observation. The profile of the emission spectra is modified by the presence of the SB depending on the angle of measurement. Such a modification is more effective for a narrow emission band and it is thus more evident in the case of Tb3+ than Eu3+. An angular effect is also observed in the lifetime, which presents two maxima and one minimum. In the case of Tb3+ the maxima are at observation angles of 35 and 50°, and the minimum at 45°. We attribute this behaviour to penetration of the excitation beam at 475 nm modulated by the stop band. The ions excited in this way emit from different depths in the crystal, and therefore their lifetime will be affected differently by the same stop band, depending on the thickness of the crystal that must be crossed. Eu3+ shows a similar but less pronounced effect for two reasons: first, the main stop band (due to the 111 planes) is not effective at the excitation wavelength of 392 nm; second, the broadness of the Eu3+ emission is comparable to the width of the SB, and a decrease in the transition rate at the wavelength of the SB maximum is compensated by an increase at the sides of the SB.  相似文献   

15.
Ferritin nanoparticles play many important roles in theranostic and bioengineering applications and have been successfully used as nanovectors for the targeted delivery of drugs due to their ability to specifically bind the transferrin receptor (TfR1, or CD71). They can be either genetically or chemically modified for encapsulating therapeutics or probes in their inner cavity. Here, we analyzed a new engineered ferritin nanoparticle, made of the H chain mouse ferritin (HFt) fused with a specific lanthanide binding tag (LBT). The HFt-LBT has one high affinity lanthanide binding site per each of the 24 subunits and a tryptophane residue within the tag that acts as an antenna able to transfer the energy to the lanthanide ions via a LRET process. In this study, among lanthanides, we selected europium for its red emission that allows to reduce overlap with tissue auto-fluorescence. Steady state emission measurements and time-resolved emission spectroscopy have been employed to investigate the interaction between the HFt-LBT and the Eu3+ ions. This allowed us to identify the Eu3+ energy states involved in the process and to pave the way for the future use of HFt-LBT Eu3+ complex in theranostics.  相似文献   

16.
By using a hydrothermal method, a series of Eu3+ concentration dependent GdF3 nanocrystals have been synthesized. The crystalline structures of samples are characterized by XRD patterns, the morphology and size of the samples are illustrated by FE-SEM images, and the optical properties of the samples are presented by PL excitation and emission spectra. The energy transfer from host Gd3+ to Eu3+ is observed in the Eu3+ doped GdF3 nanocrystals. The optical properties of Eu3+ and the energy transfer efficiency from host Gd3+ to Eu3+ are discussed on the basis of the Eu3+ concentration dependent integrated PL excitation and emission spectra of Gd3+ and Eu3+. The discussion on optical properties of Eu3+ and the energy transfer from Gd3+ to Eu3+ is meaningful to design and synthesize Gd3+ based compounds.  相似文献   

17.
We use density functional theory (DFT) to study the molecular structure and electronic band structure of Sr2Si5N8:Eu2+ doped with trivalent lanthanides (Ln3+ = Ce3+, Tb3+, Pr3+). Li+ was used as a charge compensator for the charge imbalance caused by the partial replacement of Sr2+ by Ln3+. The doping of Ln lanthanide atom causes the structure of Sr2Si5N8 lattice to shrink due to the smaller atomic radius of Ln3+ and Li+ compared to Sr2+. The doped structure’s formation energy indicates that the formation energy of Li+, which is used to compensate for the charge imbalance, is the lowest when the Sr2 site is doped. Thus, a suitable Li+ doping site for double-doped lanthanide ions can be provided. In Sr2Si5N8:Eu2+, the doped Ce3+ can occupy partly the site of Sr12+ ([SrN8]), while Eu2+ accounts for Sr12+ and Sr22+ ([SrN10]). When the Pr3+ ion is selected as the dopant in Sr2Si5N8:Eu2+, Pr3+ and Eu2+ would replace Sr22+ simultaneously. In this theoretical model, the replacement of Sr2+ by Tb3+ cannot exist reasonably. For the electronic structure, the energy level of Sr2Si5N8:Eu2+/Li+ doped with Ce3+ and Pr3+ appears at the bottom of the conduction band or in the forbidden band, which reduces the energy bandgap of Sr2Si5N8. We use DFT+U to adjust the lanthanide ion 4f energy level. The adjusted 4f-CBM of CeSr1LiSr1-Sr2Si5N8 is from 2.42 to 2.85 eV. The energy range of 4f-CBM in PrSr1LiSr1-Sr2Si5N8 is 2.75–2.99 eV and its peak is 2.90 eV; the addition of Ce3+ in EuSr1CeSr1LiSr1 made the 4f energy level of Eu2+ blue shift. The addition of Pr3+ in EuSr2PrSr2LiSr1 makes part of the Eu2+ 4f energy level blue shift. Eu2+ 4f energy level in EuSr2CeSr1LiSr1 is not in the forbidden band, so Eu2+ is not used as the emission center.  相似文献   

18.
Novel organic-inorganic mesoporous hybrid materials were synthesized by linking lanthanide (Tb3+, Eu3+) complexes to the mesoporous MCM-41 through the modified meta-methylbenzoic acid (MMBA-Si) using co-condensation method in the presence of the cetyltrimethylammonium bromide (CTAB) surfactant as template. The luminescence properties of these resulting materials (denoted as Ln-MMBA-MCM-41, Ln=Tb, Eu) were characterized in detail, and the results reveal that luminescent mesoporous materials have high surface area, uniformity in the ordered mesoporous structure. Moreover, the mesoporous material covalently bonded Tb3+ complex (Tb-MMBA-MCM-41) exhibits the stronger characteristic emission of Tb3+ and longer lifetime than Eu-MMBA-MCM-41 due to the triplet state energy of organic legend MMBA-Si matches with the emissive energy level of Tb3+ very well.  相似文献   

19.
《化学:亚洲杂志》2017,12(7):768-774
Bridged polysilsesquioxanes (BPs) show great potential in the development of lanthanide‐based luminescent materials, owing to their capacity to loading lanthanide complexes with high concentration and their flexible processability. A novel BP precursor, consisting of a C 3‐symmetrical benzene central core moiety, capable of sensitizing the luminescence of Eu3+ and Tb3+ is reported. Tunable, full‐color luminescent gels were facilely prepared by mixing the as‐synthesized precursor and Ln3+ ions in appropriate solvents. By either changing the Eu3+/Tb3+ molar ratio or altering the excitation wavelength, the emission colors of the final gels can be finely tuned. Additionally, the yellow‐colored emissive gel with a molar ratio of Eu3+ to Tb3+ of 0.5 can be used as an effective ratiometric luminescent sensor for distinguishing amines with lower pK a (<5) from those with higher pK a (>9).  相似文献   

20.
White-light emitting materials have become a hot research field of luminescent MOF (Metal–Organic Framework) because of its high practical application value. Herein, we successfully synthesized and characterized a rht-type fluorescent MOF Zn-TDPAT [H6TDPAT = 2,4,6-tris(3,5-dicarboxylphenylamino)-1,3,5-triazine] with a topology of (3, 24) connected nodes. A series of MOFs materials x%Tb + y%Eu@Zn-TDPAT were prepared by incorporating different concentrations of green emission center Tb3+ and red emission center Eu3+ into the blue-emitting Zn-MOF. The luminescence properties of MOFs materials x%Tb + y%Eu@Zn-TDPAT can be effectively adjusted by incorporating different concentrations of Tb3+ and Eu3+ and can obtain multi-color luminescence properties from blue, blue-green, green, yellow green, yellow, blue-red, yellow-red and white. According to trichromatic mechanism, by reasonably matching the intensity of blue light, green light and red light emitted by x%Tb + y%Eu@Zn-TDPAT at 420, 543 and 616 nm, MOFs materials 0.75%Tb + 5%Eu@Zn-TDPAT, 0.65%Tb + 5.5%Eu@Zn-TDPAT and 0.5%Tb + 7.5%Eu@Zn-TDPAT with white-light emission are obtained. Their CIE coordinates are 0.3162, 0.3345 (0.3162, 0.3345), (0.3138, 0.3339) and (0.3329, 0.3222), respectively, which are very close to ideal white-light emission (0.3333,0.3333).  相似文献   

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