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1.
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   

2.
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   

3.
Ca2MgSi2O7:Ce3+, Ca2MgSi2O7:Eu2+ and Ca2MgSi2O7:Eu2+,Ce3+ phosphors were prepared using the solid‐state reaction method. The crystal structures of the sintered phosphors were of melilite type, which has a tetragonal crystallography. The chemical compositions of the sintered phosphors was confirmed by energy dispersive X‐ray spectroscopy. The different thermoluminescence kinetic parameters [activation energy (E), frequency factor (s) and order of the kinetics (b)] of these phosphors were evaluated and compared using the peak shape method. Under ultraviolet excitation, the emission spectra of both Ca2MgSi2O7:Eu2+ and Ca2MgSi2O7:Eu2+,Ce3+ phosphors were composed of a broad emission band peaking at 530 nm. When the Ca2MgSi2O7:Eu2+ phosphor is co‐doped with Ce3+ ions, photoluminescence, afterglow and mechanoluminescence intensity was strongly enhanced. Ca2MgSi2O7:Eu2+ showed some afterglow with a short persist time. On incorporation of Ce3+, efficient energy transfer from Ce3+ to Eu2+ was found and the emission intensity of Eu2+ was enhanced. The mechanoluminescence intensities of Ca2MgSi2O7:Ce3+, Ca2MgSi2O7:Eu2+ and Ca2MgSi2O7:Eu2+,Ce3+ phosphors increased proportionally increased with the increase in impact velocity, which suggests that these phosphors can be used as sensors to detect stress in an object.  相似文献   

4.
Ca3SiO4Cl2 co‐doped with Ce3+,Eu2+ was prepared by high temperature reaction. The structure, luminescent properties and the energy transfer process of Ca3SiO4Cl2: Ce3+,Eu2+ were investigated. Eu2+ ions can give enhanced green emission through Ce3+ → Eu2+ energy transfer in these phosphors. The green phosphor Ca2.9775SiO4Cl2:0.0045Ce3+,0.018Eu2+ showed intense green emission with broader excitation in the near‐ultraviolet light range. A green light‐emitting diode (LED) based on this phosphor was made, and bright green light from this green LED could be observed by the naked eye under 20 mA current excitation. Hence it is considered to be a good candidate for the green component of a three‐band white LED. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

5.
White light‐emitting diodes (LEDs) for green lighting are new solutions for energy saving and environmental protection. Ca3SiO4Cl2:Ce,Eu is an efficient phosphor for white LEDs. Effective energy transfer from Ce3+ to Eu2+ occurs in Ca3SiO4Cl2:Ce,Eu due to good spectrum overlap between the emission band of Ca3SiO4Cl2:Ce and the excitation band of Ca3SiO4Cl2:Eu, and hues vary systematically from blue to green at different Ce concentrations. A great improvement in the luminescent property of Ca3SiO4Cl2:Eu has been observed on Ce3+ doping, which is attributed to energy transfer from Ce3+ to Eu2+ and an increase in the number of luminescent centers (Eu2+) on Ce doping. The optimal sample has a quantum efficiency of up to 75%, and can be an efficient green phosphor for white LEDs. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

6.
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   

7.
A series of Ca2Mg0.25Al1.5Si1.25O7:Ce3+/Eu2+/Tb3+ phosphors was been prepared via a conventional high temperature solid‐state reaction and their luminescence properties were studied. The emission spectra of Ca2Mg0.25Al1.5Si1.25O7:Ce3+,Eu2+ and Ca2Mg0.25Al1.5Si1.25O7:Ce3+,Tb3+ phosphors show not only a band due to Ce3+ ions (409 nm) but also as a band due to Eu2+ (520 nm) and Tb3+ (542 nm) ions. More importantly, the effective energy transfer from Ce3+ to Eu2+ and Tb3+ ions was confirmed and investigated by emission/excitation spectra and luminescent decay behaviors. Furthermore, the energy level scheme and energy transfer mechanism were investigated and were demonstrated to be of resonant type via dipole–dipole (Ce3+ to Eu2+) and dipole–quadrupole (Ce3+ to Tb3+) reactions, respectively. Under excitation at 350 nm, the emitting color could be changed from blue to green by adjusting the relative doping concentration of Ce3+ and Eu2+ ions as well as Ce3+ and Tb3+ ions. The above results indicate that Ca2Mg0.25Al1.5Si1.25O7:Ce3+,Eu2+/Tb3+ are promising single‐phase blue‐to‐green phosphors for application in phosphor conversion white‐light‐emitting diodes. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

8.
Ce3+/Eu2+ co‐doped Na3Ca6(PO4)5 phosphors were prepared using a combustion‐assisted synthesis method. X‐Ray powder diffraction (XRD) analysis confirmed the formation of a Na3Ca6(PO4)5 crystal phase. Na3Ca6(PO4)5:Eu2+ phosphors have an efficient bluish‐green emission band that peaks at 489 nm, whereas Ce3+‐doped Na3Ca6(PO4)5 showed a bright emission band at 391 nm. Analysis of the experimental results suggests that enhancement of the Eu2+ emission intensity in co‐doped Na3Ca6(PO4)5:Eu2+,Ce3+ phosphors is due to a resonance‐type energy transfer from Ce3+ to Eu2+ ions, which is predominantly governed by an exchange interaction mechanism. These results indicate that Ce3+/Eu2+ co‐doped Na3Ca6(PO4)5 is potentially useful as a highly efficient, bluish‐green emitting, UV‐convertible phosphor for white‐light‐emitting diodes. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

9.
In this study, using a simple combustion process and a wet chemical process, fluorides showing intense photoluminescence were prepared and developed as low‐cost phosphors. The prepared phosphors were characterized by photoluminescence (PL) techniques. PL emission spectra of the phosphor suggest the presence of Eu3+ as well as Eu2+ ions in LiMgBF6:Eu and Li2NaBF6:Eu lattice sites. This article summarizes the fundamentals and possible applications of optically useful inorganic fluoride with visible photoluminescence of doped Eu3+ and Eu2+ ions. Our results on LiMgBF6:Ce and Li2NaBF6:Ce are also reported. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

10.
CaMgSi2O6:Eu2+,Dy3+ and CaMgSi2O6:Eu2+,Ce3+ phosphors were synthesized using the solid‐state reaction method. X‐Ray diffraction (XRD) and photoluminescence (PL) analyses were used to characterize the phosphors. The XRD results revealed that the synthesized CaMgSi2O6:Eu2+,Dy3+ and CaMgSi2O6:Eu2+,Ce3+ phosphors were crystalline and are assigned to the monoclinic structure with a space group C2/c. The calculated crystal sizes of CaMgSi2O6:Eu2+,Dy3+ and CaMgSi2O6:Eu2+,Ce3+ phosphors with a main (221) diffraction peak were 44.87 and 53.51 nm, respectively. Energy‐dispersive X‐ray spectroscopy (EDX) confirmed the proper preparation of the sample. The PL emission spectra of CaMgSi2O6:Eu2+,Dy3+ and CaMgSi2O6:Eu2+,Ce3+ phosphors have a broad band peak at 444.5 and 466 nm, respectively, which is due to electronic transition from 4f65d1 to 4f7. The afterglow results indicate that the CaMgSi2O6:Eu2+,Dy3+ phosphor has better persistence luminescence than the CaMgSi2O6:Eu2+,Ce3+ phosphor. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

11.
Ca2Al2O5:Eu3+, Ca2Al2O5:Dy3+ and Ca2Al2O5:Tb3+ phosphors were synthesized using a combustion synthesis method. The prepared phosphors were characterized by X‐ray powder diffraction for phase purity, by scanning electron microscopy for morphology, and by photoluminescence for emission and excitation measurements. The Ca2Al2O5:Eu3+ phosphors could be efficiently excited at 396 nm and showed red emission at 594 nm and 616 nm due to 5D0 → 7F1 and 5D0 → 7F2 transitions. Dy3+‐doped phosphors showed blue emission at 482 nm and yellow emission at 573 nm. Ca2Al2O5:Tb3+ phosphors showed emission at 545 nm when excited at 352 nm. Concentration quenching occurred in both Eu3+ and Dy3+phosphors at 0.5 mol%. Photoluminescence results suggested that the aluminate‐based phosphor could be a potential candidate for application in environmentally friendly based lighting technologies.  相似文献   

12.
Yttrium aluminate (Y3A5O12) was doped with different rare earth ions (i.e. Gd3+, Ce3+, Eu3+ and/or Tb3+) in order to obtain phosphors (YAG:RE) with general formula,Y3‐x‐aGdxREaAl5O12 (x = 0; 1.485; 2.97 and a = 0.03). The synthesis of the phosphor samples was done using the simultaneous addition of reagents technique. This study reveals new aspects regarding the influence of different activator ions on the morpho‐structural and luminescent characteristics of garnet type phosphor. All YAG:RE phosphors are well crystallized powders containing a cubic‐Y3Al5O12 phase as major component along with monoclinic‐Y4Al2O9 and orthorhombic‐YAlO3 phases as the impurity. The crystallites dimensions of YAG:RE phosphors vary between 38 nm and 88 nm, while the unit cell slowly increase as the ionic radius of the activator increases. Under UV excitation, YAG:Ce exhibits yellow emission due to electron transition in Ce3+ from the 5d level to the ground state levels (2F5/2, 2F7/2). The emission intensity of Ce3+ is enhanced in the presence of the Tb3+ ions and is decreased in the presence of Eu3+ ions due to some radiative or non‐radiative processes that take place between activator ions. By varying the rare earth ions, the emission colour can be modulated from green to white and red. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

13.
M5(PO4)3 F:Eu2+ (M = Ca and Ba) co‐doped with Ce3+ phosphors were successfully prepared by the combustion synthesis method. The introduction of co‐dopant (Ce3+) into the host enhanced the luminescent intensity of the M5(PO4)3 F:Eu2+ (M = Ca and Ba) efficiently. Previously, we have reported the synthesis and photoluminescence properties of same phosphors. The aim of this article is to report energy transfer mechanism between Ce3+?Eu2+ ions in M5(PO4)3 F:Eu2+ (M = Ca and Ba) phosphors, where Ce3+ ions act as sensitizers and Eu2+ ions act as activators. The M5(PO4)3 F:Eu2+ (M = Ca and Ba) co‐doped with Ce3+ phosphor exhibits great potential for use in white ultraviolet (UV) light‐emitting diode applications to serve as a single‐phased phosphor that can be pumped with near‐UV or UV light‐emitting diodes. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

14.
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   

15.
KMgSO4F:Ce and KMgSO4F:Mn phosphors were prepared by a wet chemical method and studied for their photoluminescence (PL) and thermoluminescence (TL) characteristics. PL emission of KMgSO4F:Ce peaked at around 440 nm for the excitation at 377 nm due to 5d → 4f transition, while KMgSO4F:Mn had a peak at 540 nm for an excitation at 363 nm and 247 nm due to 4T1g6A1g transition. The phosphors also showed good thermoluminescence characteristics when they were exposed to γ‐rays at a 5 Gy dose at the rate of 0.36 kGyh?1. KMgSO4F:Ce exhibited a single thermoluminescence (TL) peak at around 167 °C and KMgSO4F:Mn also exhibited a single TL peak at around 177 °C. Possible trapping parameters such as order of kinetics (b), the geometrical factor (μg), the frequency factor (s) and the activation energy were also evaluated by Chen's half width method. This article discusses fundamental PL and TL characteristics in inorganic fluoride material activated by Ce3+ and Mn2+ ions and prepared by a wet chemical method. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

16.
A series of color‐tunable Ca3–2x‐y‐zSiO4Cl2 (CSC):xCe3+,xLi+,yMn2+,zEu2+ phosphors with low temperature phase structure was synthesized via the sol–gel method. An energy transfer process from Ce3+ to Mn2+ in CSC:0.01Ce3+,0.01Li+,yMn2+ (y = 0.03–0.09) and the mechanism was verified to be an electric dipole–dipole interaction. The Ce3+ and Mn2+ emission intensities were greatly enhanced by co‐doping Eu2+ ions into CSC:0.01Ce3+,0.01Li+,0.07Mn2+ phosphors due to competitive energy transfers from Eu2+/Ce3+ to Mn2+, and Ce3+ to Eu2+. Under 332 nm excitation, CSC:0.01Ce3+,0.01Li+,0.07Mn2+,zEu2+ (z = 0.0005–0.002) exhibited tunable emission colors from green to white with coexisting orange, green and violet‐blue emissions. These phosphors could have potential application in white light‐emitting diodes.  相似文献   

17.
Using a high‐temperature solid‐state reaction, the chlorine in Ba2YB2O6Cl is gradually replaced by F, and a new compound with the nominal chemical formula Ba2YB2O6F and two phosphors doped with Ce3+ and Eu3+, respectively, are obtained. X‐Ray diffraction and photoluminescence spectroscopy are used to characterize the as‐synthesized samples. The as‐synthesized Ba2YB2O6Cl exhibits bright blue emission in the spectral range ~ 330–410 nm with a maximum around 363 nm under X‐ray or UV excitation. Ba2YB2O6F:0.01Ce3+ exhibits blue emission in the range ~ 340–570 nm with a maximum around 383 nm. Ba2YB2O6F:0.01Eu3+ exhibits a predominantly 5D07 F2 emission (~610 nm) and the relative intensities of the 5D07 F0,1,2 emissions are tunable under different wavelength UV excitation. The luminescence behaviors of the two phosphors are explained simply in terms of the host composition and site occupancy probability of Ce3+ and Eu3+, respectively. The results indicate that these phosphors have potential application as a blue phosphor or as a red phosphor. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

18.
Eu3+‐doped calcium titanate red phosphors, Ca1‐xZnxTiO3:Eu3+, were prepared by the sol‐gel method. The structure of prepared Ca1‐xZnxTiO3:Eu3+ phosphors were investigated by X‐ray diffraction and infrared spectra. Due to the 5D07F1–3 electron transitions of Eu3+ ions, photoluminescence spectra showed a red emission at about 619 nm under excitation of 397 nm and 465 nm, respectively. When zinc was added to the host, the luminescent intensity of Ca1‐xZnxTiO3:Eu3+ was markedly improved several fold compared with that of CaTiO3:Eu3+. Ca0.9Zn0.1TiO3:Eu3+ also had higher luminescence intensity than the commercially available Y2O3:Eu3+ phosphors under UV light excitation. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

19.
The Eu2+/Eu3+ mixed valence phosphor Ca2SiO2F2:Eu2+/Eu3+ was prepared using a solid‐state reaction synthesis method in a CO atmosphere, and the optical properties were investigated. The spectroscopic properties revealed that Ca2+ ions were occupied by both Eu2+ and Eu3+ ions in Ca2SiO2F2, and both ions were able to generate their characteristic emissions. A broad 5d → 4f Eu2+ band at ~470 nm and narrow 4f → 4f Eu3+ peaks upon excitation with n‐UV light were observed. The ratio between Eu2+ and Eu3+ emissions changed regularly, and the relative intensity of the red component from Eu3+ became systematically stronger with increasing overall Eu content. As a result, the emission color of these phosphors can be tunable from blue to pink under n‐UV light excitation.  相似文献   

20.
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   

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