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1.
A new phosphor CaSnO3: Yb3+ was synthesized by a traditional solid-state reaction and the luminescent properties were investigated. The phosphors are well crystallized at 1200?°C. The excitation and the emission spectra show the characteristic broad of the Sn2+ ion and the X-ray photoelectron spectroscopy demonstrate the existence of Sn2+ ions caused by the doping of Yb3+ ions. The CaSnO3: Yb3+ phosphor showed a typical afterglow behavior when the UV source was switched off. Thermal simulated luminescence study indicated that the persistent afterglow of CaSnO3: Yb3+ phosphor was generated by the suitable electron or hole traps which were resulted from doping the calcium stannate host with rare-earth ions (Yb3+).  相似文献   

2.
The novel Ca4?x(PO4)2O: xDy3+ and Ca4?x?y(PO4)2O: xDy3+, yEu2+ multi-color phosphors were synthesized by traditional solid-state reaction. The crystal structure, particle morphology, photoluminescence properties and energy transfer process were investigated in detail. The X-ray diffraction (XRD) results demonstrate that the products showed pure monoclinic phase of Ca4(PO4)2O when x < 0.1. The scanning electron microscopy (SEM) indicated that the phosphors were grain-like morphologies with diameters of ~ 3.7–7.0 μm. Under excitation of 345 nm, Dy3+-doped Ca4(PO4)2O phosphors showed multi-color emission bands at 410, 481 and 580 nm originated from oxygen vacancies and Dy3+. Interestingly, Ca4(PO4)2O: Dy3+, Eu2+ phosphors exhibited blue emission band at 481 nm and broad emission band from 530 to 670 nm covering green to red regions. The energy transfer process from Dy3+ to Eu2+ was observed for the co-doped samples, and the energy transfer efficiency reached to 60% when Eu2+ molar concentration was 8%. In particular, warm/cool/day white light with adjustable CCT (2800–6700 K) and high CRI (Ra > 85) can be obtained by changing the Eu2+ co-doping contents in Ca4(PO4)2O: Dy3+, Eu2+ phosphors. The optimized Ca3.952(PO4)2O: 0.04Dy3+, 0.008Eu2+ phosphor can achieve the typical white light with CCT of 4735 K and CRI of 87.  相似文献   

3.
A series of single-phase Sr3YNa(PO4)3F:Dy3+ phosphors were successfully synthesized via a conventional solid state reaction process. The powder X-ray diffraction patterns were utilized to confirm the phase composite and crystal structure. The phosphor could be excited by the ultraviolet visible light in the region from 300 to 420 nm, and it shown two dominant emission bands peaking at 484 nm (blue light) and 580 nm (yellow light) which originated from the transitions of 4F9/26H15/2 and 4F9/26H13/2 of Dy3+, respectively. The optimum dopant concentration of Dy3+ ions was confirmed to be 7 mol% in Sr3YNa(PO4)3F:Dy3+ system and the concentration quenching mechanism is dipole–dipole interaction. The lifetime values of Dy3+ ions at different concentrations (x?=?0.03, 0.05, 0.07, 0.09 and 0.11) were determined to be about 0.855, 0.759, 0.686, 0.606 and 0.546 ms, respectively. The thermal stability of luminescence of Sr3YNa(PO4)3F:0.07Dy3+ phosphor was also investigated and the activated energy was deduced to be 0.228 eV, which shows good thermal stability. The chromaticity coordinates fall in the white-light region calculated by the emission spectrum. These results show that Sr3YNa(PO4)3F:Dy3+ phosphor can be a promising white emitting phosphor for white LEDs.  相似文献   

4.
The polycrystalline Eu2+ and RE3+ co-doped strontium aluminates SrAl2O4:Eu2+, RE3+ were prepared by solid state reactions. The UV-excited photoluminescence, persistent luminescence and thermo-luminescence of the SrAl2O4:Eu2+, RE3+ phosphors with different composition and doping ions were studied and compared. The results showed that the doped Eu2+ ion in SrAl2O4:Eu2+, Dy3+ phosphors works as not only the UV-excited luminescent center but also the persistent luminescent center. The doped Dy3+ ion can hardly yield any luminescence under UV-excitation, but can form a electron trap with appropriate depth and greatly enhance the persistent luminescence and thermo-luminescence of SrAl2O4:Eu2+. Different co-doping RE3+ ions showed different effects on persistent luminescence. Only the RE3+ ion (e.g. Dy3+, Nd3+), which has a suitable optical electro-negativity, can form the appropriate electron trap and greatly improve the persistent luminescence of SrAl2O4:Eu2+. Based on above observations, a persistent luminescence mechanism, electron transfer model, was proposed and illustrated.  相似文献   

5.
In this research, we reported the synthesis of Eu2+ and Dy3+ co-doped SrAl2O4 phosphor nanopowders with high brightness and long afterglow by urea-nitrate solution combustion synthesis (SCS) at 600 °C, followed by heating the resultant combustion ash at 1,200 °C in a weak reductive atmosphere (5% H2 + 95% N2). The broad-band UV-excited luminescence of the SrAl2O4: Eu2+, Dy3+ nanopowders was observed at λ max = 517 nm due to transitions from the 4f65d1 to the 4f7 configuration of the emission center (Eu2+ ions). The excitation spectra consist of 240- and 254 nm broad peaks. Finally, it was found that the optimum ratio of urea is 2.5 times higher than theoretical quantities for the best emission condition of SrAl2O4: Eu2+, Dy3+ phosphor nanopowders.  相似文献   

6.
The Sm3+, Dy3+ doped and Sm3+/Dy3+ co-doped NaLa(MoO4)2 spherical phosphors were hydrothermally synthesized by the EDTA-2Na mediated method. Under the excitation of 297 nm, the quenching concentration of Sm3+ in NaLa(MoO4)2 host was determined to be 13%, and the concentration quenching mechanism was discussed to be the electric quadrupole–quadrupole interaction. After Sm3+ and Dy3+ ions were co-doped into the NaLa(MoO4)2 host, the energy transfer behaviors resulted from Dy3+ to Sm3+ ions were investigated by the help of the luminescent spectra of the obtained phosphors. By varying co-doping concentrations of Sm3+/Dy3+ ions, the emission color of NaLa(MoO4)2:Sm3+/Dy3+ can be tuned from reddish-orange, pink and white to bluish-green. The CIE chromaticity coordinate, the correlated color temperature and the quantum efficiency of NaLa0.87(MoO4)2:1%Sm3+, 12%Dy3+ were calculated to be (0.356, 0.320), 4353 K and 20%, respectively. Furthermore, in the temperature-dependent analysis, it presented good thermal stability, which can become a promising single-phased white-emitting phosphor for white LEDs devices. Based on these results, the possible energy transfer mechanism between Dy3+ and Sm3+ in NaLa(MoO4)2:Sm3+/Dy3+ was also proposed.  相似文献   

7.
YAl3(BO3)4:Tb3+ phosphors were fabricated by the sol–gel method. The phosphor showed prominent luminescence in green due to the magnetic dipole transition of 5D47F5. Structural characterization of the luminescent material was carried out with X-ray powder diffraction (XRD) analysis. Luminescence properties were analyzed by measuring the excitation and photoluminescence spectra. Photoluminescence measurements indicated that the phosphor exhibited bright green emission at about 541 nm under UV excitation. It is shown that the 11% of doping concentration of Tb3+ ions in YAl3(BO3)4:Tb3+ phosphors is optimum.  相似文献   

8.
The near-infrared (NIR) long persistent phosphors have gained considerable attention owing to the potential applications in in vivo imaging. A novel NIR long-persistent phosphors Zn3Al2Ge3O12:Cr3+ was successfully synthesized by a high temperature solid-state reaction. The luminescent properties and the afterglow behaviors of the Zn3Al2Ge3O12:Cr3+ were investigated in detail. On the basis of thermoluminescence analyses, the mechanism of the persistent afterglow of the phosphors was also discussed briefly. The afterglow duration of this phosphor can last more than 12 h with the 650–750 nm emission range after stoppage of 254 nm ultraviolet light irradiation. Specifically, the persistent luminescence intensity and duration were regulated by changing Cr3+ doping concentration. All the results indicate that the Cr3+ activated Zn3Al2Ge3O12 has promising potential of practical applications.  相似文献   

9.
Emission spectral results of Pr3+ & Ho3+ ions doped Ca4GdO(BO3)3 powder phosphors are reported here. XRD, SEM and FTIR measurements have been carried out for them. The emission spectrum of Pr3+: Ca4GdO(BO3)3 has shown an emission transition 1D23H4 at 606 nm with λexci = 480 nm (3H43P0) and Ho3+: Ca4GdO(BO3)3 phosphor has shown an emission transition 5S25I8 at 549 nm with λexci = 447 nm (5I85F1). Emission performances of these two phosphors have been explained in terms of energy level diagrams.  相似文献   

10.
The alkaline orthosilicates of M2SiO4 (M = Ba, Mg, Sr) activated with Dy3+ and co-doped with Ho3+ are prepared through conventional solid-state method, i.e., mixing and grinding of solid form precursors followed by high-temperature heat treatments of several hours in furnaces, generally under open atmosphere and investigated by X-ray diffraction (XRD) to get phase properties and photoluminescence (PL) analysis to get luminescence properties. The thermal behaviours of well-mixed samples were determined by differential thermal analysis (DTA)/thermogravimetry (TG). The PL spectra show that the 478 and 572 nm maximum emission bands are attributed, respectively, to 4F9/26H15/2 and 4F9/26H13/2 transitions of Dy3+ ions.  相似文献   

11.
Zn2GeO4, Zn2GeO4:Mn2+, Zn2GeO4:Pr3+ and Zn2GeO4:Mn2+/Pr3+ phosphors were fabricated by a solid state reaction. The phase and luminescent properties of the fabricated phosphors were investigated. The XRD patterns show that all of the fabricated phosphors have an orthorhombic structure. The fabricated Zn2GeO4 shows an emission band in the range of 350–550 nm. The fabricated Zn2GeO4:Mn2+ and Zn2GeO4:Pr3+ phosphors show emission bands corresponding to Mn2+ and Pr3+ ions, respectively. The fabricated Zn2GeO4:Mn2+/Pr3+ phosphor shows the emission band results from Mn2+ and the codoped Pr3+ enhances the emission intensity of Mn2+. Moreover, Zn2GeO4:Mn2+/Pr3+ phosphor exhibits longer decay time than that of Zn2GeO4:Mn2+. The higher intensity and longer lifetime of Mn2+ emission are induced by the energy transfer from Pr3+ of various vacancies to Mn2+ in Zn2GeO4:Mn2+/Pr3+ phosphors.  相似文献   

12.
Eu2+ and Tb3+ doped Ca2MgSi2O7 phosphors were synthesized by conventional solid-state reaction. The phase formation was confirmed by X-ray powder diffraction technique and refined lattice parameters were calculated by rietveld refinement process using Celref v3. The photoluminescence (PL) excitation and emission spectra were investigated. The phosphors exhibited broaden green emitting luminescence peaking at 520 nm when excited at 374 nm source. Morphological studies were carried out using Scanning electron microscopy (SEM) images of the sample with optimum PL emission. The dependence of photoluminescence intensity on co-dopant concentration and the kinetic parameters were also reported. Time resolved fluorescence spectroscopy (TRFS) is used to investigate the decay in luminescence signals with respect to time. The sample proved to be a good long lasting material, which makes it useful in emergency signs, textile printing, textile exit sign boards and electronic instrument dial pads etc.  相似文献   

13.
A series of novel red-emitting Na2Ca3???x Si2O8:xEu3+ phosphors were synthesized by solid state reactions. The phosphors can strongly absorb 395 nm light, and show red emission with a good color purity. The excitation and emission spectra properties of Na2Ca3Si2O8:Eu3+ were characterized. Na2Ca3Si2O8:Eu3+ with self-compensated and alkali metal ions charge compensated approaches (2Ca2+→Eu3+ + M+, M?=?Li+, Na+, K+) have investigated, which found that the red emission of luminescent intensity can be greatly enhanced, and shows superior luminescent property to the commercial Y203S:Eu3+. The present work implies that the efficient charge compensated phosphors are promising candidates as red-emitting phosphor for w-LEDs.  相似文献   

14.
Y2O3:Eu3+ phosphors were prepared by hydrothermal method. Effect of the doping concentration of Eu3+ on the photoluminescence properties of Y2O3:Eu3+ phosphor was studied in details. It was found that the strongest emission intensity is achieved as atomic ratio of Y3+ to Eu3+ is 8. As concentration of Eu3+ exceeds the critical concentration, the emission intensity decreases dramatically due to the concentration quenching of Eu3+. Also, the effect of Li+ on the photoluminescence performance of the Y2O3:Eu3+ phosphor is studied in this work. According to the results, the doping of Li+ may greatly improve the PL performance of the Y2O3:Eu3+ phosphors due to the flux effect and improved crystallinity caused by the doping of Li+.  相似文献   

15.
The influence of activation of the Y2O3 matrix of the Y2O3:Eu3+ phosphor by Bi3+ ions on the luminescence of Eu3+ and Bi3+ ions in it and on conditions of the excitation energy transfer to luminescence centers is studied. It is shown that the presence of Bi3+ ions leads to the appearance of recombination luminescence with participation of bismuth ions at low concentrations (up to 6–8 at %) of the dominant activator europium and to an increase in the threshold of intrinsic concentration quenching of its luminescence.  相似文献   

16.
The ultraviolet (UV)-emitting Sr3P4O13:Ce3+ phosphors were synthesized via the solid-state reaction method, and their structural, morphological and luminescence properties were characterized by X-ray diffraction analysis, scanning electron microscopy, photoluminescence spectroscopy. The obtained results indicate that these phosphors can be effectively excited by short-wavelength ultraviolet (<300 nm), and exhibit long-wavelength ultraviolet (300–380 nm) emission with nanosecond-level fluorescence lifetime corresponding to the parity-allowed 5d–4f transitions of Ce3+. The concentration-quenching phenomenon of Ce3+ in Sr3P4O13 host was also studied, in which the critical energy transfer distance between Ce3+ ions and concentration quenching mechanism were determined.  相似文献   

17.
A series of Pr3+, Gd3+ and Pr3+–Gd3+-doped inorganic borate phosphors LiSr4(BO3)3 were successfully synthesized by a modified solid-state diffusion method. The crystal structures and the phase purities of samples were characterized by powder X-ray diffraction. Surface morphology of the sample was studied by scanning electronic microscopy (SEM). The optimal concentrations of dopant Gd3+ ions in compound LiSr4(BO3)3 were determined through the measurements of photoluminescence (PL) spectra of phosphors. Gd3+-doped phosphors LiSr4(BO3)3 show strong band absorption in UV spectral region and narrow-band UVB emission under the excitation of 276 nm was only due to 6P J 8S7/2 transition of Gd3+ ions. The effect of Pr3+ ion on excitation of LiSr4(BO3)3:Gd3+ was also studied. The excitation of LiSr4(BO3)3:Gd3+, Pr3+ gives a broad-band spectra, which show very good overlap with the Hg 253.7 nm line. The photoluminescence spectra of LiSr4(BO3)3 with different doping concentrations Pr3+ and keeping the concentration of Gd3+ constant at 0.03 mol have also been studied. The emission intensity of LiSr4(BO3)3:Pr3+–Gd3+ phosphors increases with increasing Pr3+ doping concentration and reaches a maximum at 0.01 mol. From the photoluminescence study of LiSr4(BO3)3:Gd3+, Pr3+ we conclude that there was efficient energy transfer from Pr3+→ Gd3+ ions in LiSr4?x?y Pr x Gd y (BO3)3 phosphors.  相似文献   

18.
The SrLa2?xO4:xEu3+ phosphors are synthesized through high-temperature solid-state reaction method at 1473 K with various doping concentration. Their phase structures, absorption spectra, and luminescence properties are investigated by X-ray diffraction (XRD), UV–Vis spectrophotometer and photoluminescence spectrometry. The intense absorption of SrLa2?xO4:xEu3+ phosphors have occurred around 400 nm. The prominent luminescence spectra of the prepared phosphors exhibited bright red emission at 626 nm. The doping concentration 0.12 mol% of Eu3+ is shown to be optimal for prominent red emission and chromaticity coordinates are x?=?0.692, y?=?0.3072. Considering the high colour purity and appropriate emission intensity of Eu3+ doped SrLa2O4 can be used as red phosphors for white light emitting diodes (WLEDs).  相似文献   

19.
Bluish green emitting phosphor, Ca3Al2O6:Ce3+, is prepared by low-temperature combustion method. X-ray diffraction, photoluminescence, scanning electron microscopy techniques are used to characterize the synthesized phosphor. The most efficient bluish green (483 nm) emission is observed under the excitation by near UV light. The emission characteristics are credited to 5d → 4f type transitions in Ce3+. The luminescence properties of Eu2+ are predicted for the first time from those of Ce3+. Also, photoluminescence of Eu3+ is studied in the same host. The emission spectrum of Ca3Al2O6:Eu3+ shows the peak at 592 (orange) and 614 nm (red) wavelengths. Ca3Al2O6:Ce3+phosphor can be a potential blue phosphor for field emission display, solid-state lighting and LED.  相似文献   

20.
LiEu1−x (W2−y Mo y )O8:xBi3+ series red-emitting phosphors were synthesized by solid state reaction. The structure, morphology, and photoluminescent properties of phosphors were studied by X-ray powder diffraction, scanning electron microscopy, and photoluminescence spectrum, respectively. X-ray powder diffraction analysis showed that the as-obtained phosphors belong to the scheelite structure. The average particle size of the investigated phosphor was about 8 μm. The excitation spectrum exhibits a charge-transfer broad band along with some sharp peaks from the typical 4f–4f transitions of Eu3+. Under excitation of UV, near-UV, or blue light, these phosphors showed strong red emission at 615 nm due to 5D07F2 transition of Eu3+. The incorporation of Mo6+ into LiEuW2O8:Bi3+ could induce red-shift of the charge-transfer broad band and a remarkable increase of photoluminescence. The highest red-emission intensity was observed with LiEu0.80Mo2O8:0.20Bi3+. Compared with the commercial red-emitting phosphor, Y2O2S:Eu3+, the emission intensity of LiEu0.80Mo2O8:0.20Bi3+ phosphor is much stronger than that of Y2O2S:Eu3+ and its chromaticity coordinates are closer to the standard values than that of the commercial phosphor. The optical properties of LiEu0.80Mo2O8:0.20Bi3+ phosphor make it attractive for the application in white-light-emitting diodes (LEDs), in particular for near-UV InGaN-based white-LEDs.  相似文献   

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