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1.
Y2‐xGeMoO8:REx (RE = Eu, Tb) phosphors were synthesized using a facile sol–gel method. The morphology and structure of the phosphors were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X‐ray diffraction (XRD); while their luminescent properties were investigated by photoluminescence (PL) spectrometry. Our results reveal that all of these Y2‐xGeMoO8:REx (RE = Eu, Tb) phosphors adopted the tetragonal phase, belonging to Scheelite (CaWO4) structure. The obtained YGeMoO8:Eu phosphors exhibit a strong emission in the red light range which can be assigned to the 5D07F2 transition of Eu3+ when it is excited at 459 nm. Under 392 and 489 nm excitation, the YGeMoO8:Tb phosphors present predominant green emission (5D47F5) at 540 nm. The highest emission of the phosphors can be achieved by adjusting the doping concentration to be 0.25 for Eu3+ and 0.15 for Tb3+, respectively. The promising luminescence properties of these materials indicate that they can be potentially applied to white‐light‐emitting diodes. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

2.
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   

3.
KBaPO4 luminescent powdered phosphors doped with rare earth elements (RE = Sm3+,Eu3+,Dy3+) were successfully synthesized using a wet chemical method to identify the most suitable phosphor for solid‐state lighting based on the measurement of their emission spectra at excitation wavelengths. The X‐ray diffraction pattern of the as‐prepared KBaPO4 was well matched with its standard JCPDS file no. 330996, indicating the formation of the desired compound. Scanning electron microscopy images revealed irregular morphology, the material crystallized particles aggregated and were non‐uniform with particle sizes ranging from 1 to 100 μm. Photoluminescence excitation and emission spectra clearly indicated that the phosphor containing the Sm3+‐activated KBaPO4 phosphors could be efficiently excited at 403 nm and exhibited an emission mainly including two wavelength peaks at 559 nm and 597 nm. The phosphor containing the Eu3+‐activated KBaPO4 phosphors could be efficiently excited at 396 nm and exhibited a bright red emission mainly including two wavelength peaks at 594 nm and 617 nm. The phosphor containing the Dy3+‐activated KBaPO4 phosphors could be efficiently excited at 349 nm and exhibited wavelength peaks at 474 nm and 570 nm.  相似文献   

4.
In this work, we report the preparation, characterization, comparison and luminescence mechanisms of Eu2+‐doped and Eu2+,Dy3+‐co‐doped Ba2MgSi2O7 (BMSO) phosphors. Prepared phosphors were synthesized via a high temperature solid‐state reaction method. All prepared phosphors appeared white. The phase structure, particle size, and elemental analysis were analyzed using X‐ray diffraction (XRD), transmission electron microscopy (TEM) and energy‐dispersive X‐ray (EDX) analysis. The luminescence properties of the phosphors were investigated by thermoluminescence (TL) and photoluminescence (PL). The PL excitation and emission spectra of Ba2MgSi2O7:Eu2+ showed the peak to be around 381 nm and 490 nm respectively. The PL excitation spectrum of Ba2MgSi2O7:Eu2+Dy3+ showed the peak to be around 341 nm and 388 nm, and the emission spectrum had a broad band around 488 nm. These emissions originated from the 4f6 5d1 to 4f7 transition of Eu2+. TL analysis revealed that the maximum TL intensity was found at 5 mol% of Eu2+ doping in Ba2MgSi2O7 phosphors after 15 min of ultraviolet (UV) light exposure. TL intensity was increased when Dy3+ ions were co‐doped in Ba2MgSi2O7:Eu2+ and maximum TL intensity was observed for 2 mol% of Dy3+. TL emission spectra of Ba1.95MgSi2O7:0.05Eu2+ and Ba1.93MgSi2O7:0.05Eu2+,0.02Dy3+ phosphors were found at 500 nm. TL intensity increased with UV exposure time up to 15 min, then decreased for the higher UV radiation dose for both Eu doping and Eu,Dy co‐doping. The trap depths were calculated to be 0.54 eV for Ba1.95MgSi2O7:0.05Eu2+ and 0.54 eV and 0.75 eV for Ba1.93MgSi2O7:0.05Eu2+,0.02Dy3+ phosphors. It was observed that co‐doping with small amounts of Dy3+ enhanced the thermoluminescence properties of Ba2MgSi2O7 phosphor. Copyright © 2016 John Wiley & Sons, Ltd. [Correction added on 5 April 2016, after first online publication: The following parts of the abstract have been edited for consistency. '4f65d1' has been corrected to '4f6 5d1', '4f7' has been corrected to '4f7', 'Ba1.95' has been corrected to 'Ba1.95' and 'Ba1.93' has been corrected to 'Ba1.93' respectively.]  相似文献   

5.
Modified synthesis and luminescence of Y2BaZnO5 phosphors activated with the rare earths (RE) Eu3+, Tb3+, Pr3+ and Sm3+ are reported. RE2BaZnO5 phosphors have attracted attention because of their interesting magnetic and optical properties; and are usually prepared using a two‐step solid‐state reaction. In the first step, carbonates or similar precursors are thoroughly mixed and heated at 900°C to decompose them to oxides. To eliminate the unwanted phases like BaRE2O4, the resulting powders are reheated at 1100°C for a long time. We prepared Y2BaZnO5 phosphors activated with various activators by replacing the first step with combustion synthesis. The photoluminescence results are presented. The photoluminescence results for Eu3+, Tb3+ and Pr3+ are in good agreement with the literature. However, photoluminescence emission from Sm3+ has not been documented previously. The excitation spectrum of Eu3+ is dominated by a charge transfer band around 261 nm, and an additional band around 238 nm is always present, irrespective of the type of activator. The presence of this band for all these different types of activators was interpreted as host absorption.  相似文献   

6.
The luminescence of novel rare earth ( Tb 3 + , Eu 3 + and Dy 3 + )‐activated Ba 2 Sr 2 Al 2 O 7 phosphors for solid‐state lighting is presented. The aluminate phosphors were synthesized using a one‐step combustion method. X‐Ray diffraction, scanning electron microscopy and photoluminescence characterizations were performed to understand the mechanism of excitation and the corresponding emission in the as‐prepared phosphor, as characterized the phase purity and microstructure. Improvements in the luminescence properties of the phosphors with rare earth concentration were observed. The phosphor hue could be tuned from blue, green and red by proper selection of rare earth ions in typical concentrations. Effective absorption in the near‐ultraviolet region was observed, which makes the phosphor a potential candidate for ultraviolet light‐emitting diodes. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

7.
A green chemical precipitation route was used to yield a hydrated basic sulfate precursor upon calcination at 1000°C into a series of (Y,Gd)2O2SO4:Dy particles. The phosphors exhibited characteristic Dy3+ emissions from 4F9/26HJ (J = 15/2, 13/2, 11/2) transitions under ultraviolet light excitation; the quenching concentration of Dy3+ was determined to be 2.5 at.%. Substitution of Gd3+ for Y3+ led to an additional strong sharp band at ~277 nm (8S7/26IJ transition of Gd3+) in the photoluminescence excitation spectra, upon which the (Gd0.975Dy0.025)2O2SO4 phosphor achieved a ~2.8-fold higher photoluminescence intensity via an effective energy transfer from Gd3+ to Dy3+ compared with the 354 nm excitation of Dy3+. Both the photoluminescence and photoluminescence excitation intensities of (Y,Gd)2O2SO4:Dy phosphors increased with rising Gd3+ concentration and calcination temperature in the range 750–1000°C. A higher Gd3+ concentration slightly prolonged the effective fluorescence lifetime.  相似文献   

8.
In this study, a series of LaNbTiO6:RE3+ (RE = Tb, Dy, Ho) down‐converting phosphors were synthesized using a modified sol–gel combustion method, and their photoluminescence (PL) properties were investigated as a function of activator concentration and annealing temperature. The resultant particles were characterized using X‐ray diffraction, transmission electron microscopy, scanning electron microscopy, UV/Vis diffuse reflectance spectroscopy and PL spectra. The highly crystalline LaNbTiO6:RE3+ (RE = Tb, Dy, Ho) phosphors with an average size of 200–300 nm obtained at 1100°C have an orthorhombic aeschynite‐type structure and exhibit the highest luminescent intensity in our study range. The emission spectra of LaNbTiO6:RE3+ (RE = Tb, Dy, Ho) phosphors under excitations at UV/blue sources are mainly composed of characteristic peaks arising from the f–f transitions of RE3+, including 489 nm (5D47F6) and 545 nm (5D47F5) for Tb3+, 476 and 482 nm (4F9/26H15/2) and 571 nm (4F9/26H13/2) for Dy3+, and 545 nm (5F4 + 5S25I8) for Ho3+, respectively. The luminescent mechanisms were further investigated. It can be expected that these phosphors are of intense interest and potential importance for many optical applications. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

9.
Eu3+‐activated Y(P,V)O4 phosphors were prepared by the EDTA sol‐gel method, and the corresponding morphologies and luminescent properties were investigated. The sample particles were relatively spheroid with size of 2–3 µm and had a smooth surface. The excitation spectra for Y(P,V)O4:Eu3+ consisted of three strong excitation bands in the 200–350 nm range, which were attributed to a Eu3+‐ O2? charge‐transfer band and 1A1?1 T1/1 T2 transitions in VO43?. The as‐synthesized phosphors exhibited a highly efficient red luminescence at 613 nm due to the Eu3+ 5D0?7 F2 electric dipole transition. With the increase in the V5+/P5+ ratio, the luminescence intensity of the red phosphor under UV excitation was greatly improved due to enhanced VO43? → Eu3+ energy transfer. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

10.
Li3PO4 phosphors prepared by solid‐state diffusion technique and lyoluminescence (LL) as well as mechanoluminescence (ML) studies are reported. Dy‐ and Tb‐activated phosphors show dosimetric characteristics using LL and ML techniques. The energy levels and hence trapping and detrapping of charge carriers in the material can be studied using ML. Li3PO4 phosphor can be used in the dosimetric applications for ionizing radiation. By using the LL technique, the LL characteristics of Li3PO4 may be useful for high radiation doses. We also report a more detailed theoretical understanding of the mechanism of LL and ML. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

11.
Rare earth ions (Eu3+ or Tb3+)‐activated Ca3 Ga2 Si3O12 (CaGaSi) phosphors were synthesized by using a sol–gel method. Photoluminescence spectra of Eu3+:CaGaSi phosphors exhibited five emission bands at 578, 592, 612, 652 and 701 nm, which were assigned to the transitions (5D07F0, 7F1, 7F2, 7F3 and 7F4), respectively, with an excitation wavelength of λexci = 392 nm. Among these, the transition 5D07F2 (612 nm) displayed bright red emission. In the case of Tb3+:CaGaSi phosphors, four emission bands were observed at 488 (5D47F6), 543 (5D47F5), 584 (5D47F4) and 614 nm (5D47F3) from the measurement of PL spectra with λexci = 376 nm. Among these, the transition 5D47F5 at 543 nm displayed bright green emission. The structure and morphology of the phosphors were studied from the measurements of X‐ray diffraction (XRD), scanning electron microscopy (SEM) and energy‐dispersive X‐ray analysis (EDAX) results. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

12.
In this paper, the Eu3+–Eu2+ (4%, molar ratio)‐doped xAl2O3–ySiO2 (x = 0–2.5, y = 1–5) and xAl2O3–zMgO (x = 0–1.5, z = 0–3) composites phosphors with different Al2O3 to SiO2 (A/S) and Al2O3 to MgO (A/M) ratios were prepared using a high‐temperature solid‐state reaction under air atmosphere. The effects of the A/S and A/M on luminescence properties, crystal structure, electron spin resonance, and Commission Internationale de l’Eclairage chromaticity coordinates of the samples were systematically analyzed. These results indicated that the different A/S and A/M ratios in the matrix effectively affected the crystal phase, degrees of self‐reduction of Eu3+, and led the relative emission intensity of Eu2+/Eu3+ to change and adjust.  相似文献   

13.
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   

14.
Rare‐earth ions play an important role in eco‐friendly solid‐state lighting for the lighting industry. In the present study we were interested in Eu3+ ion‐doped inorganic phosphors for near ultraviolet (UV) excited light‐emitting diode (LED) applications. Eu3+ ion‐activated SrYAl3O7 phosphors were prepared using a solution combustion route at 550°C. Photoluminescence characterization of SrYAl3O7:Eu3+ phosphors showed a 612 nm emission peak in the red region of the spectrum due to the 5D07F2 transition of Eu3+ ions under excitation at 395 nm in the near‐UV region and at the 466 nm blue excitation wavelength. These red and blue emissions are supported for white light generation for LED lighting. Structure, bonding between each element of the sample and morphology of the sample were analysed using X‐ray diffraction (XRD) and scanning electron microscopy (SEM), which showed that the samples were crystallized in a well known structure. The phosphor was irradiated with a 60Co‐γ (gamma) source at a dose rate of 7.2 kGy/h. Thermoluminescence (TL) studies of these Eu3+‐doped SrYAl3O7 phosphors were performed using a Nucleonix TL 1009I TL reader. Trapping parameters of this phosphor such as activation energy (E), order of kinetics (b) and frequency factor (s) were calculated using Chen's peak shape method, the initial rise method and Ilich's method.  相似文献   

15.
Photoluminescence (PL) and thermoluminescence (TL) properties of rare earth (RE) ion (RE = Dy3+, Sm3+, Ce3+, Tb3+) activated microcrystalline BaMgP2O7 phosphors are presented in this work. Non‐doped and doped samples of BaMgP2O7 were prepared using a solid state diffusion method and characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), PL and TL. The XRD measurement confirmed the phase purity of the BaMgP2O7 host matrix. The average particle size was found through SEM measurement to be around 2 μm. All activators using the PL technique displayed characteristic excitation and emission spectra that corresponded to their typical f → f and f → d transitions respectively. Thermoluminescence measurements showed that BaMgP2O7:RE (RE = Dy3+, Sm3+, Tb3+, Ce3+) and co‐doped BaMgP2O7:Ce3+,Tb3+ phosphors have also TL behaviour.  相似文献   

16.
In this article, we report the synthesis of Na2Sr1‐x(PO4)F:Eux phosphor via a combustion method. The influence of different annealing temperatures on the photoluminescence properties was investigated. The phosphor was excited at both 254 and 393 nm. Na2Sr1‐x(PO4)F:Eux3+ phosphors emit strong orange and red color at 593 and 612 nm, respectively, under both excitation wavelengths. Na2Sr1‐x(PO4)F:Eux3+ phosphors annealed at 1050°C showed stronger emission intensity compared with 600, 900 and 1200°C. Moreover, Na2Sr1‐x(PO4)F:Eux3+ phosphor was found to be more intense when compared with commercial Y2O3:Eu3+ phosphor. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

17.
Dy3+ and Eu3+ activated Ca3Y2Si3O12 phosphors were synthesized by the solid‐state synthesis method. The phosphors were characterized by X‐ray diffraction (XRD), mechanoluminescence (ML), thermoluminescence (TL) and photoluminescence (PL) to determine structure and luminescence. For ML glow curves, only one peak was observed, as only one type of luminescence centre was formed during irradiation. The Ca3Y2Si3O12:Dy3+ TL glow curve showed a single peak at 151.55°C and the Ca3Y2Si3O12:Eu3+ TL glow curve peaked at 323°C with a small peak at 192°C, indicating that two types of traps were activated. The trapping parameters for both the samples were calculated using Chen's peak shape method. Dy3+‐activated Ca3Y2Si3O12 showed emission at 482 and 574 nm when excited by a 351 nm excitation wavelength, whereas the Eu3+‐activated Ca3Y2Si3O12 phosphor PL emission spectra showed emission peaks at 613 nm, 591 nm, 580 nm when excited at 395 nm wavelength. When excited at 466 nm, prominent emission peaks were observed at their respective positions with very slight shifts. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

18.
A series of single‐phase phosphors based on Na6Mg(SO4)4 (Zeff = 11.70) doped with Dy and Eu was prepared by the wet chemical method. The photoluminescence (PL) and thermoluminescence (TL) properties of Dy3+‐ and Eu3+‐activated Na6Mg(SO4)4 phosphors were investigated. The characteristic emissions of Dy3+ and Eu3+ were observed in the Na6Mg(SO4)4 host. The TL glow curve of the Na6Mg(SO4)4:Dy phosphor consisted of a prominent peak at 234°C and a very small hump at 158°C. The TL sensitivity of the Na6Mg(SO4)4:Dy phosphor was found to be four times less than the commercialized CaSO4:Dy phosphor. The TL dose–response of the Na6Mg(SO4)4:Dy phosphor was studied from a dose range of 5–10 kGy and the linear dose–response was observed up to 1 kGy which is good for a microcrystalline phosphor. Trapping parameters for both the samples were calculated using the Initial Rise and Chen's peak shape methods.  相似文献   

19.
Gd 3 +‐ activated oxysulphide ( M2O2S ) may be used to study Photoluminescence (PL) properties with respect to phototherapy . Gd 3 +‐ activated phosphor materials are widely used for phototherapy lamps . The Gd 3 + ion gives characteristic Narrow-Band (NB) emissions , in particular in the ultraviolet ( UV ) light region , that are used to treat more than 50 types of skin diseases . In this paper , M2O2S oxysulphide doped with Gd 3 + was synthesized by the solid‐state flux fusion method and its down conversion spectral properties were studied as a function of different Gd 3 + concentrations . The sample was characterized by X-ray Diffraction (XRD) , Scanning Electron Microscope (SEM) , Fourier Transform Infrared Spectroscopy (FT‐IR) , and PL and the crystal structure was also studied . The lanthanum oxysulphide ( La2O2S )‐ activated Gd 3 + ion showed a sharp emission peak at 314 nm when excited at 275 nm excitation , whereas the yttrium oxysulphide ( Y2O2S )‐ activated Gd 3 + ion showed a sharp emission at 316 nm when excited by 272 nm . The effect of concentration of the Gd 3 + ion on the luminescence properties of M2O2S : Gd 3 + phosphor was also studied . These phosphor materials activated with the Gd 3 + ion may be suitable for phototherapy lamps , which are used to treat many types of skin diseases such as psoriasis , vitiligo , or scleroderma. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

20.
In this paper, we have reported the photoluminescence (PL) properties of the Ba2Mg(PO4)2:Eu3+ phosphor synthesized using a wet chemical method. The preliminary scanning electron microscopy (SEM) investigation of the sample revealed irregular surface morphology with particle sizes in the 10–50 μm range. The strongest PL excitation peak was observed at 396 nm. The emission spectra indicated that this phosphor can be effectively excited by the 396 nm wavelength. Upon 396 nm excitation, the emission spectrum showed characteristics peaks located at 592 nm and 615 nm. These intense orange‐red emission peaks were obtained due to f→f transitions of Eu3+ ions. The emission peak at 592 nm is referred to as the magnetic dipole 5D07F1 transition and the emission peak at 615 nm corresponded to the electric dipole 5D07F2 transition of Eu3+. The Commission Internationale de l’Eclairage (CIE) coordinates of the Ba2Mg(PO4)2:Eu3+ phosphor were found to be (0.586, 0.412) for wavelength 592 nm and (0.680, 0.319) for wavelength 615 nm situated at the edge of the CIE diagram, indicating high colour purity of phosphors. Due to the high emission intensity and a good excitation profile, Eu3+‐doped Ba2Mg(PO4)2 phosphor may be a promising orange‐red phosphor candidate for solid‐state lighting applications.  相似文献   

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