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1.
Gd2O3:Eu3+ (4 mol%) co-doped with Bi3+ (Bi = 0, 1, 3, 5, 7, 9 and 11 mol%) ions were synthesized by a low-temperature solution combustion method. The powders were calcined at 800°C and were characterized by powder X-ray diffraction (PXRD), transmission electron microscopy (TEM), Fourier transform infrared and UV–Vis spectroscopy. The PXRD profiles confirm that the calcined products were in monoclinic with little cubic phases. The particle sizes were estimated using Scherrer’s method and Williamson–Hall plots and are found to be in the ranges 40–60 nm and 30–80 nm, respectively. The results are in good agreement with TEM results. The photoluminescence spectra of the synthesized phosphors excited with 230 nm show emission peaks at ~590, 612 and 625 nm, which are due to the transitions 5D07F0, 5D07F2 and 5D07F3 of Eu3+, respectively. It is observed that a significant quenching of Eu3+ emission was observed under 230 nm excitation when Bi3+ was co-doped. On the other hand, upon 350 nm excitation, the luminescent intensity of Eu3+ ions was enhanced by incorporation of Bi3+ (5 mol%) ions. The introduction of Bi3+ ions broadened the excitation band of Eu3+ of which a new strong band occurred ranging from 320 to 380 nm. This has been attributed to the 6s2→6s6p transition of Bi3+ ions, implying a very efficient energy transfer from Bi3+ ions to Eu3+ ions. The gamma radiation response of Gd2O3:Eu3+ exhibited a dosimetrically useful glow peak at 380°C. Using thermoluminescence glow peaks, the trap parameters have been evaluated and discussed. The observed emission characteristics and energy transfer indicate that Gd2O3:Eu3+, Bi3+ phosphors have promising applications in solid-state lighting.  相似文献   

2.
Undoped and PbNb2O6:Eu3+ (1.0 ≤ x ≤ 6.0 mol%) phosphors were synthesized at 1100 °C for 3.5 h by the conventional solid state reaction method. Synthesized PbNb2O6:Eu3+ phosphors were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive spectroscopy (EDS) and Photoluminescence (PL) analyses. The PL spectra showed series of excitation peaks between 350 and 430 nm due to the 4f–4f transitions of Eu3+. For 395.0 nm excitation, emission spectra of Eu3+ doped samples were observed at 591 nm (orange) and 614 nm (red) due to the 5D0 → 7F1 transitions and 5D0 → 7F2 transitions, respectively. PL analysis results also showed that the emission intensity increased by increasing Eu3+ ion content. No concentration quenching effect was observed. The CIE chromaticity color coordinates (x,y) of the PbNb2O6:Eu3+ phosphors were found to be in the red region of the chromaticity diagram.  相似文献   

3.
《Current Applied Physics》2015,15(6):748-752
Eu3+-doped Ba0.7Sr0.3TiO3 thin films were prepared by a chemical solution deposition method and characterized by X-ray diffraction, field emission scanning electron microscopy, photoluminescence and dielectric measurements. The thin films were well crystallized with a pure perovskite structure. A contraction of the unit cell was observed upon incorporation of Eu3+ ions below 2 mol%, while an expansion occurred as the Eu3+ concentration was further increased above 2 mol%, indicating that Eu3+ ions with different concentrations occupied different lattice sites. Photoluminescence spectra showed two prominent transitions of Eu3+ ions at 594 nm (5D0 → 7F1) and 618 nm (5D0 → 7F2) upon excitation at 395 nm (7F0 → 5L6). There existed two quenching concentrations at 2 mol% and 4 mol% due to different lattice sites of the Eu3+ ions. We also investigated the dielectric properties of the thin films. Our study suggests that Eu3+-doped Ba0.7Sr0.3TiO3 thin films have potential applications in multifunctional optoelectronic devices.  相似文献   

4.
Undoped and Eu3+-doped cubic yttria (Y2O3) nanophosphors of good crystallinity, with selective particle sizes ranging between 6 and 37 nm and showing narrow size distributions, have been synthesized by a complex-based precursor solution method. The systematic size tuning has been evidenced by transmission electron microscopy, X-ray diffraction, and Raman scattering measurements. Furthermore, size-modulated properties of Eu3+ ions have been correlated with the local structure of Eu3+ ion in different sized Y2O3:Eu3+ nanophosphors by means of steady-state and time-resolved site-selective laser spectroscopies. Time-resolved site-selective excitation measurements performed in the 7F0 → 5D0 peaks of the Eu3+ ions at C2 sites have allowed us to conclude that Eu3+ ions close to the nanocrystal surface experience a larger crystal field than those in the nanocrystal core. Under the site-selective excitation in the 7F0 → 5D0 peaks, energy transfer between the sites has also been observed.  相似文献   

5.
Abstract

The fluorescence spectra of Y2O3:Eu3+ nanoparticles have been measured under the pressure of up to 78 kbar at room temperature. In this pressure range, a red-shift of 0.02(1) nm/kbar?1 is noticed for the 0–2 line (5D07F2 transition). This shift is explained by the change of negative charge of the surrounding ligands. Compatibility between measured and calculated values for the 0–2 line position was obtained. The luminescence decay curves of the 5D07F2 transition were studied up to 78 kbar and were found to behave exponentially for all pressures studied. The fluorescence lifetime τ for the 0–2 line (5D07F2 transition) slowly decreased with pressure. The pressure effect on τ for the 0–2 line (5D07F2 transition) was explained by a model which considers the pressure effect on the line position, inter-ionic distance, ion volume and polarizability, molecular volume and polarizability, molecular refractive index and the refractive index medium n med of the surrounding hydrostatic medium. The fluorescence lifetime calculated by the present model is in close correspondence with the experimental values.  相似文献   

6.
Eu3+-doped Na0.5Bi0.5TiO3 (Eu:NBT) single crystals were grown by a top-seeded solution growth method. Photoluminescence emission and excitation spectra of Eu:NBT were investigated. The two transitions in 7F0 → 5D0 excitation spectra reveal that Eu3+ ions were incorporated into two adjacent crystallographic sites in NBT, i.e., Bi3+ and Na+ sites. The former has a symmetrical surrounding, while the later has a disordered environment, which was confirmed by decay curve measurements. The dielectric dispersion behavior was depressed and the piezoelectric and ferroelectric properties were improved after Eu doping.  相似文献   

7.
张林进  叶旭初 《发光学报》2009,30(2):184-188
采用高温固相法合成了SrB4O7 : Eu荧光粉,并研究了不同原料、掺杂浓度、煅烧温度等因素对其发光性能的影响。发射光谱测试结果表明:SrB4O7 : Eu荧光粉的最佳Eu掺杂浓度为2%左右,进一步增大掺杂浓度会导致浓度猝灭。煅烧温度对基质组成影响较大,随着温度的升高,基质中BO4四面体所占比例增大,有利于Eu3+离子的还原。以水合硼酸锶为原料制得样品的发光强度高于以SrCO3和H3BO3为原料制得样品的发光强度。  相似文献   

8.
Effects of the high pressure on the emission spectra of Eu3+-activated L-EuBO3 were considered at room temperature up to 100 kbar. The position of five 0–2 lines in the 5D07F2 transition region was determined. The pressure does not have the same effect on all these lines. In four of them, high pressure induced a red shift with different shift rates:+0.0022,+0.0035,+0.0034 and+0.0027 nm kbar?1, respectively, whereas in the last one, high pressure induced a blue shift with shift rate?0.0034 nm kbar?1. Possible reasons for the mentioned pressure effects on the line positions were considered.  相似文献   

9.
This paper focuses on the synthesis and the photoluminescent properties of Ca3−xAl2O6:xEu3+ (0≤x≤0.1) nanophosphors prepared by microwave-assisted combustion method without any further heat treatment. X-ray diffraction, scanning electron microscopy and photoluminescence spectroscopy were used to characterize the produced samples. Nanosized particles smaller than 120 nm were obtained as confirmed by SEM. When exposed to UV light radiation at 254 nm, the europium-doped nanoparticles showed strong reddish-orange luminescence due to the characteristic transitions 5D07F1 (orange) and 5D07F2, (red). The maximum emission intensity of the visible emission was obtained for x=0.05. It was also found that higher doping concentrations led to the luminescence quenching by a cross-relaxation mechanism between Eu3+ ions in the lattice.  相似文献   

10.
Hexagonal YPO4 phosphors doped with Eu3+/Dy3+ and co-doped with Ce3+ were synthesized by a hydrothermal route assisted using lauric acid as a capping agent. The prepared phosphors were characterized by transmission electron microscopy, infrared spectroscopy, powder X-ray diffraction and photoluminescence spectra. YPO4: Eu3+ gives two red emission peaks at 587 and 610?nm corresponding to 5D07F1 and 5D07F2 transitions, respectively. YPO4: Dy3+ exhibits two emission peaks at 485?nm (blue) and 575?nm (yellow) corresponding to 4F9/26H15/2 and 4F9/26H13/2 transitions, respectively. Ce3+ ions enhanced the emission intensity as a co-dopant in both phosphors. Moreover, the effect of γ-radiation in the dose range 5–300?kGy on the photoluminescence behaviour of YPO4:Eu3+,Ce3+ and YPO4:Dy3+,Ce3+ was also investigated. Quenching of emission intensity, after irradiation at 5 and 300?kGy, was observed in both the phosphors due to loss of excess energy through a non-radiative relaxation process.  相似文献   

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