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1.
KNaSO4 microphosphor doped with Ce,Gd and Ce,Tb and prepared by a wet chemical method was studied using X‐ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence (PL) characterization. KNaSO4 has a 5‐µm particle size detected by SEM. KNaSO4:Ce3+,Tb3+ showed blue and green emission (at 494 nm, 557 nm, 590 nm) of Tb3+ due to 5D47FJ (J = 4, 5, 6) transitions. KNaSO4:Ce3+,Gd3+ showed luminescence in the ultraviolet (UV) light region at 314 nm for an excitation at 271 nm wavelength. It was observed that efficient energy transfer took place from Ce3+ → Gd3+ and Ce3+ → Tb3+ sublattices indicating that Ce3+ could effectively sensitize Gd3+ or Tb3+ (green emission). Ce3+ emission weakened and Gd3+ or Tb3+ enhanced the emission significantly in KNaSO4. This paper discusses the development and understanding of photoluminescence and the effect of Tb3+ and Gd3+ on KNaSO4:Ce3+. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

2.
Chlorosulphate NaMgSO4Cl phosphor doped with Ce3+ and co‐doped by Dy3+ prepared by the wet chemical method was studied for its photoluminescence and thermoluminescence (TL) characteristics. The emission spectrum of Ce3+ shows dominant peaks at 346 nm (excitation 270 nm) due to 5d → 4f transition. Efficient energy transfer occurs from Ce3+ → Dy3+ ions. Dy3+ emission at 485 nm and 576 nm is due to 4 F9/26H15/2 and 4 F9/26H13/2 transitions of Dy3+ ion respectively. The TL glow curves of NaMgSO4Cl:Ce and Ce,Dy have been recorded for various concentrations at a heating rate of 2 °C/s irradiated by γ‐rays at a dose rate of 0.995 kGy/h for 1 Gy, which peaks at about 241 °C and 247‐312 °C respectively. Further, in changing the concentration level, the general structure of the intensity is found to increase. The main property of this phosphor is its sensitivity even for low concentrations of rare earth ions and low γ‐ray dose. There is still scope for higher doses of γ‐radiation. The phosphor presented may be used as a lamp phosphor as well as for TL studies. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

3.
The individual emission and energy transfer between Ce3+ and Eu2+ or Dy3+ in BaCa(SO4)2 mixed alkaline earth sulfate phosphor prepared using a co‐precipitation method is described. The phosphor was characterized by X‐ray diffraction (XRD) and photoluminescence (PL) studies and doped by Ce;Eu and Dy rare earths. All phosphors showed excellent blue–orange emission on excitation with UV light. PL measurements reveal that the emission intensity of Eu2+ or Dy3+ dopants is greater than when they are co‐doped with Ce3+. An efficient Ce3+ → Eu2+ [2T2g(4f65d) → 8S7/2(4f7)] and Ce3+ → Dy3+ (4 F9/26H15/2 and 4 F9/26H13/2) energy transfer takes place in the BaCa(SO4)2 host. A strong blue emission peak was observed at 462 nm for Eu2+ ions and an orange emission peak at 574 nm for Dy3+ ions. Hence, this phosphor may be used as a lamp phosphor. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

4.
The compound Na3SO4Cl X (X = Ce3+, Eu3+ or Dy3+) prepared by the wet chemical method was studied for its photoluminescence (PL) and energy transfer characteristics. The PL from Na3SO4Cl:Ce3+ shows strong emission at 322 nm at an excitation of 272 nm. Therefore, an efficient Ce3+ → Dy3+, Eu2+ → Dy3+ and Eu2+ → Eu3+ energy transfer had taken place in this host. The Dy3+ emission caused by Ce3+ → Dy3+ energy transfer under ultraviolet (UV) wavelengths peaked at around 477 nm and 572 nm due to 4 F9/26H15/2 and 6H13/2 transitions with yellow–orange emission in the Na3SO4Cl lattice. An intense Dy3+ emission was observed at 482 and 576 nm caused by the Eu2+ → Dy3+ energy transfer process and due to 4 F9/26H15/2 and 4 F9/26H13/2 transitions respectively. The Eu3+ blue to red light emission caused by the Eu2+ → Eu3+ energy transfer peaked at 593 nm and 617 nm due to 5D05D3 transitions. The presence of trivalent Eu in Na3SO4Cl suggested the presence of Eu3+ in the host compound that occupied two different lattice sites and that peaked at 593 and 617 nm due to 5D07 F1 and 5D07 F2 transitions respectively. The trivalent europium ion is very useful for studying the nature of metal coordination in various systems due to its non‐degenerate emitting 5D0 state. The present paper discusses the photoluminescence characteristics of Eu2+ → Dy3+ and Eu2+ → Eu3+ energy transfer. This compound may be useful as a lamp phosphor. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

5.
Sr3MgSi2O8:Ce3+, Dy3+ phosphors were prepared by a solid‐state reaction technique and the photoluminescence properties were investigated. The emission spectra show not only a band due to Ce3+ ions (403 nm) but also as a band due to Dy3+ ions (480, 575 nm) (UV light excitation). The photoluminescence properties reveal that effective energy transfer occurs in Ce3+/Dy3+ co‐doped Sr3MgSi2O8 phosphors, and the co‐doping of Ce3+ could enhance the emission intensity of Dy3+ to a certain extent by transferring its energy to Dy3+. The Ce3+/Dy3+ energy transfer was investigated by emission/excitation spectra, and photoluminescence decay behaviors. In Sr2.94MgSi2O8:0.01Ce3+, 0.05Dy3+ phosphors, the fluorescence lifetime of Dy3+ (from 3.35 to 27.59 ns) is increased whereas that of Ce3+ is greatly decreased (from 43.59 to 13.55 ns), and this provides indirect evidence of the Ce3+ to Dy3+ energy transfer. The varied emitted color of Sr3MgSi2O8:Ce3+, Dy3+ phosphors from blue to white were achieved by altering the concentration ratio of Ce3+ and Dy3+. These results indicate Sr3MgSi2O8:Ce3+, Dy3+ may be as a candidate phosphor for white light‐emitting diodes. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

6.
A novel phosphor LiBaPO4 doped with rare earths Eu and Dy prepared by high temperature solid‐state reaction method is reported. The phosphors were characterized by X‐ray powder diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence (PL). The emission and excitation spectra of these materials were measured at room temperature with a spectrofluorophotometer. The excitation spectra of LiBaPO4:Eu3+ phosphor can be efficiently excited by 394 nm, which is matched well with the emission wavelength of near‐UV light‐emitting diode (LED) chip. PL properties of Eu3+‐doped LiBaPO4 exhibited the characteristic red emission coming from 5D07 F1 (593 nm) and 5D07 F2 (617 nm) electronic transitions with color co‐ordinations of (0.680, 0.315). The results demonstrated that LiBaPO4:Eu3+ is a potential red‐emitting phosphor for near‐UV LEDs. Emission spectra of LiBaPO4:Dy3+ phosphors showed efficient blue (481 nm) and yellow (574 nm) bands, which originated from 4 F9/26H15/2 and 4 F9/26H13/2 transitions of the Dy3+ ion, respectively. The 574 nm line is more intense than the 481 nm lines, which indicates that the site Dy3+ is located with low symmetry. This article summarizes fundamentals and possible applications of optically useful inorganic phosphates with visible photoluminescence of Eu3+ and Dy3+ ions. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

7.
The photoluminescence and thermoluminescence characteristics of rare earths (Dy or Ce) activated LiCaBO3 phosphors have been studied. Phosphors were synthesized by modified solid state synthesis. The phosphors were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL) and thermoluminescence (TL) for structural, morphological and luminescence studies. Dy3+ activated LiCaBO3 shows emission at 486 and 577 nm due to 4 F9/26H15/2 and 4 F9/26H13/2 transition, respectively, whereas the PL emission spectra of Ce3+ activated LiCaBO3 phosphor shows a broad band peaking at 432 nm, which is due to the transition from 5d level to the ground state of the Ce3+ ion. The thermoluminescence study was also carried out for both these phosphors for γ‐ray irradiation and carbon beam irradiation. Linearity was studied for a 0.4–3.1 Rad dose γ‐rays. Linear behaviour over this dose range was observed. Gamma ray‐irradiated phosphors were shown to be negligible fading upon storage. All the samples were also studied for 75 MeV C5+ ion beam exposure in the range of 3.75 × 1012 – 7.5 × 1013 ion cm–2 fluence. In addition to this, trapping parameters of all the samples were also calculated using Chen's peak shape method. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

8.
The CaAlBO4:RE (RE = Dy3+, Eu3+, Sm3+) phosphor were prepared via combustion synthesis and studied by X-ray diffraction (XRD), Fourier-transform infrared (FTIR) analysis, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), photoluminescence (PL) spectra and CIE coordinates. The phase formation of the obtained phosphor was analyzed by XRD and the result was confirmed by standard PDF Card No. 1539083. XRD data successfully indicated pure phase of CaAlBO4 phosphor. The crystal structure of CaAlBO4 phosphor is orthorhombic with space group Ccc2 (37). The SEM image of CaAlBO4 phosphor reveals an agglomerated morphology and non-uniform particle size. The EDS image provides evidence of the elements present and the chemical makeup of the materials. Under the 350 nm excitation, the emission spectrum of Dy3+ activated CaAlBO4 phosphor consists of two main groups of characteristic peaks located at 484 and 577 nm which are ascribed to 4F9/26H15/2 and 4F9/26H13/2 transition of Dy3+ respectively. The PL emission spectra of CaAlBO4:Eu3+ phosphor shows characteristics bands observed around 591 and 613 nm, which corresponds to 5D07F1 and 5D07F2 transition of Eu3+ respectively, upon 395 nm excitation wavelength. The emission spectra of Sm3+ activated CaAlBO4 phosphor shows three characteristic bands observed at 565, 601 and 648 nm which emits yellow, orange and red color. The prominent emission peak at the wavelength 601 nm, which is attributed to 4G5/26H7/2 transition, displays an orange emission. The CIE color coordinates of CaAlBO4:RE (RE = Dy3+, Eu3+, Sm3+) phosphor are calculated to be (0.631, 0.368), (0.674, 0.325) and (0.073, 0.185). As per the obtained results, CaAlBO4:RE (RE = Dy3+, Eu3+, Sm3+) phosphor may be applicable in eco-friendly lightning technology.  相似文献   

9.
A new phosphor CaAl(SO4)2Br doped with Dy, Ce and Eu is reported. Rare earth (Dy, Eu and Ce)‐doped polycrystalline CaAl(SO4)2Br phosphors were prepared using a wet chemical reaction method and studied for X‐ray diffraction and photoluminescence (PL) characteristics. Dy3+ emission in the CaAl(SO4)2Br lattice was observed at 484 and 574 nm in the blue and yellow regions of the spectrum, which are assigned to 4 F9/26H15/2 and 4 F9/26H13/2 transitions of the Dy3+ ion, respectively. While the PL emission spectra of CaAl(SO4)2Br:Ce phosphor showed Ce3+ emission at 347 nm due to 5d → 4f transition of the Ce3+ ion. In a CaAl(SO4)2Br:Eu lattice, Eu3+ emissions were observed at 593 and 617 nm, coming from the 5D07 F1 and 5D07 F2 electron transitions, respectively. The PL study showed that the intensity of electric dipole transition at 617 nm dominates over that of magnetic dipole transition at 590 nm. The maximum PL intensity was obtained for a 1 mol% concentration of Eu3+ in CaAl(SO4)2Br host lattice. The results showed that the material may be a promising candidate as a blue‐, yellow‐ and red‐emitting phosphor. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

10.
A new Na3Ca2(SO4)3F: Ce3+ phosphor synthesized by a solid state diffusion method is reported. The photoluminescence study showed a single high intensity emission peak at 307 nm wavelength when excited by UV light of wavelength 278 nm. An unresolved peak of comparatively less intensity was also observed at 357 nm along with the main peak. The characteristic emission of dopant Ce in Na3Ca2(SO4)3F phosphor clearly indicated that it resides in the host lattice in trivalent form. The emission peak can be attributed to 5d → 4f transition of rare earth Ce3+. The prepared sample is also characterized for its thermoluminescence properties. The TL glow curve of prepared sample showed a single broad peak at 147°C. The trapping parameters are also evaluated by Chen's method. The values of trap depth (E) and frequency factor (s) were found to be 0.64 ± 0.002 eV and 1.43 × 107 s–1 respectively. The study of PL and TL along with evaluation of trapping parameters has been undertaken and discussed for the first time. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

11.
Long persistence phosphor CaAl4O7: Eu2+, Dy3+ were prepared by a combustion method. The phosphors were characterized by means of X‐ray diffraction (XRD), scanning electron microscopy (SEM), decay time measurement techniques and photoluminescence spectra (PL). The CaAl4O7: Eu2+, Dy3+ phosphor showed a broad blue emission, peaking at 445 nm when excited at 341 nm. Such a blue emission can be attributed to the intrinsic 4f → 5d transitions of Eu2+ in the host lattices. The lifetime decay curve of the Dy3+ co‐doped CaAl4O7: Eu2+ phosphor contains a fast decay component and another slow decay one. Surface morphology also has been studied by SEM. The calculated CIE colour chromaticity coordinates was (0.227, 043). We have also discussed a possible long‐persistent mechanism of CaAl4O7:Eu2+, Dy3+ phosphor. All the results indicate that this phosphor has promising potential for practical applications in the field of long‐lasting phosphors for the purposes of sign boards and defence. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

12.
This review discusses the photoluminescence (PL) characteristics of halosulfate phosphors developed by us. Halosulfate phosphors KCaSO4Cl:X,Y (X = Eu or Ce; Y = Dy or Mn) and Na6(SO4)2FCl (doped with Dy, Ce or Eu) were prepared using a solid‐state diffusion method. The mechanism of energy transfer from Eu2+→Dy3+, Ce3+→Dy3+ and Ce3+→Mn2+ has also been studied. Dy3+ emission in the host at 475 and 570 nm is observed due to 4F9/26H15/2 and 4F9/26H13/2 transition, whereas the PL emission spectra of Na6(SO4)2FCl:Ce phosphor shows Ce3+ emission at 322 nm due to 5d→4f transition of the Ce3+ ion. The main property of KCaSO4Cl is its very high sensitivity, particularly when doped by Dy, Mn or Pb activators. This review also discusses the PL characteristics of some new phosphors such as LiMgSO4F, Na6Pb4(SO4)6Cl2, Na21Mg(SO4)10Cl3 and Na15(SO4)5F4Cl. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

13.
A new halophosphor K3Ca2(SO4)3 F activated by Eu or Ce and K3Ca2(SO4)3 F:Ce,Eu co‐doped halosulfate phosphor has been synthesized by the co‐precipitation method and characterized for its photoluminescence (PL). The PL emission spectra of the K3Ca2(SO4)3 F :Ce phosphor show emission at 334 nm when excited at 278 nm due to 5d → 4f transition of Ce3+ ions. In the K3Ca2(SO4)3 F:Eu lattice, Eu2+ (440 nm) as well as Eu3+ (596 nm and 615 nm) emissions have been observed showing 5D07 F1 and 5D07 F2 transition of the Eu3+ ion, which is in the blue and red region of the visible spectrum respectively. The trivalent europium ion is very useful for studying the nature of metal coordination in various systems owing to its non‐degenerate emitting 5D0 state. K3Ca2(SO4)3 F:Ce,Eu is suitable for Ce3+ → Eu2+ → Eu3+ energy transfer in which Ce3+and Eu2+ play the role of sensitizers and Eu2+ and Eu3+ act as the activators. The observations presented in this paper are relevant for lamp phosphors. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

14.
A series of Sr2P2O7:Dy3+, Sr2P2O7:Ce3+ and Sr2P2O7:Dy3+,Ce3+ phosphors was synthesized via the one‐step calcination process for the precursors prepared by co‐precipitation methods. The phases, morphology, quantum efficiency and photoluminescence properties of the obtained phosphors were characterized systematically. These results show that the near‐spherical particles prepared through calcining the precursors by means of ammonium dibasic phosphate co‐precipitation (method 3) have the smallest particle size and strongest emission intensity among the three methods in the paper. With Dy3+ concentration increasing in Sr2P2O7:Dy3+ phosphors, the luminescence intensity first increases, reaches maximum, and then decreases. A similar trend was followed by Sr2P2O7:Ce3+ with Ce3+concentration increasing. A successful attempt was made to initiate the energy transfer mechanism from Ce3+ to Dy3+ in the host lattice and an overlap between the emission band of Ce3+ and the excitation band of Dy3+ indicated that the Ce3+ → Dy3+ energy transfer may indeed exist. It is clear that the photoluminescence intensity of Dy3+ as well as the quantum efficiency of the phosphor can be enhanced markedly by co‐doping Ce3+. Sr2P2O7:Dy3+,Ce3+ has its (CIE) chromaticity coordinates in the bluish‐white‐light region, near the standard illuminant D65. The CIE 1913 chromaticity coordinates of Sr2P2O7:Dy3+ phosphors fall in the white‐light region, and are adjacent to the ideal white‐light coordinates. In addition, the colour temperature and colour tone of Sr2P2O7:Dy3+ could be adjusted by changing the relative concentration of Dy3+. In short, Sr2P2O7:Dy3+ can be a promising single‐phased white‐light emitting phosphor for near‐UV (NUV) w‐LEDs.  相似文献   

15.
KCe(PO3)4 doped with Dy3+,Tb3+,Yb3+and Nd3+ phosphors were synthesized by a solid state diffusion method. The prepared samples were characterized by X‐ray diffraction and photoluminescence. KCe(PO3)4 exhibits emission in ultraviolet (UV) region which indicates weak Ce3+–Ce3+ interaction. The Ce3+–Ce3+energy transfer is not efficient. In light of this, energy transfer from Ce3+ to other lanthanides like Dy3+, Tb3+,Yb3+ and Nd3+ is rather surprising.  相似文献   

16.
A series of Eu3+‐, Ce3+‐, Dy3+‐ and Tb3+‐doped (Y,Gd)BO3 phosphors was synthesized by a solid‐state diffusion method. X‐Ray diffraction confirmed their hexagonal structure and the scanning electron microscopy results showed crystalline particles. The excitation spectra revealed that (Y,Gd)BO3 phosphors doped with Eu3+, Ce3+ , Dy3+ and Tb3+ are effectively excited with near UV‐light of 395 nm/blue light, 364, 351 and 314 nm, respectively. Photoluminescence spectra of Eu3+‐, Ce3+‐ and Tb3+/Dy3+‐doped phosphor showed intense emission of reddish orange, blue and white light, respectively. The phosphor Y0.60Gd0.38BO3:Ce0.02 showed CIE 1931 color coordinates of (0.158, 0.031) and better color purity compared with commercially available blue BAM:Eu2+ phosphor. The phosphor (Y,Gd)BO3 doped with Eu3+, Dy3+ and Tb3+ showed CIE 1931 color coordinates of (0.667, 0.332), (0.251, 0.299) and (0.333, 0.391) respectively. Significant photoluminescence characteristics of the prepared phosphors indicate that they might serve as potential candidates for blue chip and near‐UV white light‐emitting diode applications. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

17.
An inorganic NaMgSO4F fluoride material was prepared by the wet chemical method and studied for its photoluminescence (PL) and resonant–non‐resonant energy transfer (RET and NORET) capabilities between Ce3+ → Tb3+, Ce3+ → Eu3+ and Ce3+ → Dy3+ rare earth ions. The Tb3+ emission for Ce3+ → Tb3+ transfers under ultraviolet (UV) wavelengths peaked at 491, 547, and 586 nm, for excitation at 308 nm due to 5D4 → 7FJ (J = 4, 5, 6) transitions. Eu emission spectra were observed at 440 nm (Eu2+), 593 nm and 616 nm (Eu3+) recorded for different concentrations of materials, whereas Dy3+ emission from Ce3+ → Dy3+ transfer under UV wavelengths peaked at 485 nm and 577 nm due to 4F9/2 → 6H15/2 and 6H13/2 transitions. The purpose of the present study is to understand the RET and NORET effects of Tb3+, Eu3+ and Dy3+ co‐doping in a NaMgSO4F:Ce3+ luminescent material, which could be used as a green‐emitting material for lamp phosphors.  相似文献   

18.
The present communication is strongly focused on the investigation of synthesis, structural and luminescence properties of cerium (Ce3+)- and europium (Eu3+)-activated Zn4Al22O37 phosphors. Ce3+- and Eu3+-doped Zn4Al22O37 novel phosphors were prepared using a solution combustion synthesis route. Structural properties were studied using powder X-ray diffraction and high-resolution transverse electron microscopy. The optical properties were studied using ultraviolet–visible light spectroscopy and Fourier transform infrared spectroscopy; luminescence properties were studied using a photoluminescence (PL) technique. The crystal structure of the prepared Zn4Al22O37 host and Ce3+- and Eu3+-activated Zn4Al22O37 phosphors was investigated and was found to have a hexagonal structure. The measured PL emission spectrum of the Ce3+-doped Zn4Al22O37 phosphor showed an intense and broad emission band centred at 421 nm under a 298 nm excitation wavelength. By contrast, the Eu3+-doped Zn4Al22O37 phosphor exhibited two strong and intense emission bands at approximately 594 nm (orange) and 614 nm (red), which were monitored under 395 nm excitation. The Commission Internationale de l’Eclairage (CIE) colour coordinates of the Ce3+-doped Zn4Al22O37 were investigated and found to be x = 0.1567, y = 0.0637 (blue) at 421 nm and for Eu3+-doped Zn4Al22O37 were x = 0.6018, y = 0.3976 (orange) at 594 nm and x = 0.6779, y = 0.3219 (red) at 614 nm emission. The luminescence behaviour of the synthesized phosphors suggested that these phosphors may be used in lighting applications.  相似文献   

19.
The preparation of Ce3+‐doped Sr6AlP5O20 and Ba6AlP5O20 by a combustion method is described. Formation of compounds was confirmed by X‐ray diffraction (XRD) analysis. The photoluminescence (PL) emission spectra were observed at 355 nm when excited at 307 nm for the various concentrations. The PL emission spectra of phosphors showed strong Ce3+ emission due to the 5 d → 4f transition of Ce3+ ions. The Ce3+ emission intensity in Sr6AlP5O20:Ce phosphor was higher than that in Ba6AlP5O20:Ce and it may be useful for scintillation applications. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

20.
LiCaBO3:Dy3+/Eu3+ phosphors were synthesized by a solid‐state reaction. The synthesized materials were characterized using powder X‐ray diffraction pattern (XRD) for confirmation. All the structural parameters were calculated from the XRD data. Scanning electron microscopy (SEM) images showed rod‐like morphology. Photoluminescence (PL) emission spectra showed two emissions (484 and 577 nm) in Dy3+‐doped LiCaBO3:Dy3+phosphors with the concentration quenching effect and the critical distance was calculated to be about 22.76 Å. LiCaBO3:Eu3+ phosphor was effectively excited by a near‐UV light of 392 nm. The emission spectra exhibited the transition from 5D0 level to 7FJ (J = 0–2) with main emission at 614 nm, which comes from the electrodipole transition because of the asymmetric point group. The quenching concentration of Eu3+ is about 0.2 mol%, and the critical distance was calculated to be about 38.93 Å. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

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