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1.
A series of novel red‐emitting Sm3+‐doped bismuth silicate phosphors, Bi4Si3O12:xSm3+ (0.01 ≤ x ≤ 0.06), were prepared via the sol–gel route. The phase of the synthesized samples calcinated at 800 °C is isostructural with Bi4Si3O12 according to X‐ray diffraction results. Under excitation with 405 nm light, some typical peaks of Sm3+ ions centered at 566, 609, 655 and 715 nm are found in the emission spectra of the Sm3+‐doped Bi4Si3O12 phosphors. The strongest peak located at 609 nm is due to 4G5/26H7/2 transition of Sm3+. The luminescence intensity reaches its maximum value when the Sm3+ ion content is 4 mol%. The results suggest that Bi4Si3O12:Sm3+ may be a potential red phosphor for white light‐emitting diodes. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

2.
A new yellowish‐orange emitting phosphor, Ba2B10O17:Sm3+ for use as a white light‐emitting diode (W‐LED) was synthesized by a solid‐state reaction method. The X‐ray diffraction results indicated that a pure Ba2B10O17 material was obtained. As a potential yellowish‐orange luminescent material for W‐LEDs, the Ba2B10O17:Sm3+ phosphor could be excited effectively by near‐ultraviolet (n‐UV) light and exhibited yellowish‐orange emission centered at 560 nm corresponding to the 4G5/2 → 6H5/2 transition of Sm3+ ions. The optimum concentration of Sm3+ ions in Ba2B10O17, critical transfer distance (Ra) and concentration quenching mechanism of the presented phosphor were investigated. Moreover, CIE chromaticity coordinates and color purity performance of the Ba2B10O17:Sm3+ phosphor were also discussed. The present work suggests that the Ba2B10O17:Sm3+ phosphor has potential as a type of yellowish‐orange emitting phosphor. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

3.
A near ultraviolet excitable phosphor based on Sm3+‐doped YAl3(BO3)4 has been synthesized by modified solid‐state reaction at 1000°C. The phase purity and photoluminescence (PL) behavior of the phosphor are studied in detail using the powder X‐ray diffraction technique and PL measurements. X‐ray diffraction reveals that the phase purity of YAl3(BO3)4 critically depends upon the boric acid concentration. The phosphor has strong excitation at 406 nm in the near ultraviolet region (350–420 nm) and its emission peaks were monitored at 564, 599 and 643 nm. Further, detailed PL analysis demonstrates that the substitution of Sm3+ ions at sites of Y3+ and Al3+ ions enhances the PL efficiency of the phosphor appreciably. First, the PL efficiency of YAl3(BO3)4:Sm3+ was compared with commercial (Y,Gd)BO3:Eu3+ red phosphor. The Fourier transform infrared study provides essential information regarding the change in metal–oxygen bond vibrations of the phosphor. The morphology of the phosphor was investigated through scanning electron microscopy, which reveals that the phosphor possessed distorted spherical and rectangular shapes with average grain sizes in the range 0.5–1 µm. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

4.
This paper focuses on an optical study of a Tb3+/Bi3+‐doped and Sm3+/La3+‐ doped Ca2Al2SiO7 phosphor synthesized using combustion methods. Here, Ca2Al2SiO7:Sm3+ showed a red emission band under visible light excitation but, when it co‐doped with La3+ ions, the emission intensity was further enhanced. Ca2Al2SiO7:Tb3+ shows the characteristic green emission band under near‐ultraviolet light excitation wavelengths, co‐doping with Bi3+ ions produced enhanced photoluminescence intensity with better colour tunable properties. The phosphor exhibited better phase purity and crystallinity, confirmed by X‐ray diffraction. Binding energies of Ca(2p), Al(2p), Si(2p), O(1s) were studied using X‐ray photoelectron spectroscopy. The reported phosphor may be a promising visible light excited red phosphor for light‐emitting diodes and energy conversion devices.  相似文献   

5.
Zn‐doped CaTiO3:Eu3+ red phosphors for enhanced photoluminescence in white light‐emitting diodes (LEDs) were synthesized by a solid‐state method. The structure and morphology of the obtained phosphor samples were observed by X‐ray diffraction (XRD) and scanning electron microscopy (SEM), and the impact of Ca, Zn and Eu content on their photoluminescence properties was studied. The results indicated that Zn not only participates in the formation of defects in suitable lattice matrices but also has a role in flux in the transformation from ZnO to Zn2TiO4, which is beneficial for the enhancement of photoluminescence properties. Photoluminescence test data showed that the Zn‐doped phosphor is excited efficiently by near‐ultraviolet (NUV) light at wavelengths around 398 nm and emits an intense red light with a broad peak around 616 nm corresponding to the 5D07F2 transition of Eu3+. The intensity of this phosphor emission is three times stronger than that without Zn‐doping. Furthermore, this phosphor has very good thermal stability, high color purity and a low sintered temperature, all of which suggest its potential as a promising red phosphor for white LEDs. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

6.
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   

7.
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   

8.
A series of Sr2ZnWO6 phosphors co‐doped with Eu3+, Bi3+ and Li+ were prepared using the Pechini method. The samples were tested using X‐ray diffraction and luminescence spectroscopy. The results show that the samples can be effectively excited by near‐ultraviolet (UV) and UV light. The introduction of Bi3+ and Li+ significantly enhances the fluorescence emission of Sr2ZnWO6:Eu3+ and changes the light emitted by the phosphors from bluish‐green to white. When excited at 371 nm, Sr2–x–zZn1–yWO6:xEu3+,yBi3+,zLi+ (x = 0.05, y = 0.05, z = 0.05, 0.1 and 0.15) samples emit high‐performance white light. Intense red–orange emission is also observed when excited by UV light. The obtained phosphor is a potential white‐emitting phosphor that could meet the needs of excitation sources with near‐UV chips. In addition, this phosphor might have promising application as a red–orange emitting phosphor for white light‐emitting diodes based on UV light‐emitting diodes. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

9.
A novel tunable red emitting phosphor LiBaB9O15:Sm2+/Sm3+, Li+ with broad excitation band was synthesized by a high temperature solid‐state method. Luminescence properties were investigated in detail by luminescence, X‐ray photoelectron spectroscopy (XPS) spectra and CIE chromaticity coordinates. XPS data confirmed that there were Sm3+ in LiBaB9O15:Sm3+ and Sm2+/Sm3+ in LiBaB9O15:Sm2+/Sm3+, respectively. Spectral property of LiBaB9O15:Sm3+, LiBaB9O15:Sm3+/Sm2+ and LiBaB9O15:Sm2+, Li+ presented that the excitation band of Sm3+ widened and the excitation band of Sm2+ ranged from 350 to 450 nm. And the red light color is tunable with changing Li+ concentration. The results indicated that LiBaB9O15:Sm2+/Sm3+, Li+ may be promising red phosphor for white light emitting diodes.  相似文献   

10.
Sm3+ ions doped strontium lithium lead borate glasses (SLLB:Sm) were prepared using a conventional melt‐quenching technique. The glasses were analyzed using X‐ray diffractometry and Fourier transform infrared spectroscopy, optical absorption, fluorescence spectral analysis, and fluorescence lifetime decay. The Judd–Ofelt (J–O) parameters and radiative parameters of the SLLB:Sm10 glass (1.0 mol% Sm3+ ion‐doped glass) were calculated using J–O theory. From the emission spectra, among all the synthesized glass, SLLB:Sm10 glass had the highest emission intensity for 4G5/26H11/2 transition (610 nm). Emission parameters, such as stimulated emission cross‐section and optical gain bandwidth, were calculated. For all concentrations of Sm3+ ions, the decay profile showed an exponential nature and decreased when the Sm3+ ion concentration was increased due to a concentration quenching effect. This result suggests that the synthesized SLLB:Sm10 glass could be used for application in high‐density optical memory devices.  相似文献   

11.
Dy3+‐doped CaAl12O19 phosphors were synthesized utilizing a combustion method. Crystal structure and morphological examinations were performed respectively using X‐ray diffraction (XRD) and scanning electron microscopy (SEM) techniques to identify the phase and morphology of the synthesized samples. Fourier transform infrared spectroscopy (FTIR) estimations were carried out using the KBr method. Photoluminescence properties (excitation and emission) were recorded at room temperature. CaAl12O19:Dy3+ phosphor showed two emission peaks respectively under a 350‐nm excitation wavelength, centered at 477 nm and 573 nm. Dipole–dipole interaction via nonradiative energy shifting has been considered as the major cause of concentration quenching when Dy3+ concentration was more than 3 mol%. The CIE chromaticity coordinates positioned at (0.3185, 0.3580) for the CaAl12O19:0.03Dy3+ phosphor had a correlated color temperature (CCT) of 6057 K, which is situated in the cool white area. Existing results point out that the CaAl12O19:0.03Dy3+ phosphor could be a favorable candidate for use in white light‐emitting diodes (WLEDs).  相似文献   

12.
Europium (Eu3+) and bismuth (Bi3+) co‐activated LiBaBO3 powder phosphors were synthesized by a solid‐state reaction and the structure, particle morphology, optical and photoluminescent properties were investigated. X‐Ray diffraction patterns of the LiBaBO3 phosphors crystallized in a pure monoclinic phase, i.e. there were no secondary phases due to either incidental impurities or undecomposed starting materials. Scanning electron microscopy images showed that the powders were made up of fluffy needle‐like particles that were randomly aligned. The band‐gap of the LiBaBO3 host was estimated to be 3.33 eV from the UV/vis absorption data. Blue emission was observed from the LiBaBO3 host, which is ascribed to self‐activation of the host matrix. In addition, greenish‐blue (493 nm) and red (613 nm) emissions were observed from europium‐doped samples and were attributed to the emissions of Eu2+ and Eu3+, respectively. Furthermore, after codoping with Bi3+, the emission intensity of Eu3+ located at 613 nm was significantly enhanced. From the Commission Internationale de I′Eclairage (CIE) color coordinates, white emission was observed from LiBa1–xBO3:xEu3+ (x = 0.020 and 0.025) phosphor powders with color coordinates of x = 0.368, y = 0.378 and x = 0.376, y = 0.366, respectively.  相似文献   

13.
Cr3+‐doped Y2O3 (0.5–9 mol%) was synthesized by a simple solution combustion method using Aloe vera gel as a fuel/surfactant. The final obtained product was calcined at 750°C for 3 h, which is the lowest temperature reported so far for the synthesis of this compound. The calcined product was confirmed for its crystallinity and purity by powder X‐ray diffraction (PXRD) studies which showed a single‐phase nano cubic phosphor. The particles size estimated by Scherrer formula was in the range of 6–19 nm. The UV–vis spectra showed absorption bands at 198, 272 and 372 nm having band gap energy in the range 4.00–4.26 eV. In order to investigate the possibility of its use in white light emitting display applications, the photoluminescence properties of Cr3+‐doped Y2O3 nanophosphors were studied at an excitation wavelength in the near ultraviolet (UV) light region (361 nm). The emission spectra consisted of emission peaks in the blue (4F9/2 → 6H15/2), orange (4F9/2 → 6H13/2) and red (4F9/2 → 6H11/2) regions. The CIE coordinates (0.33, 0.33) lie in the white light region. Hence Y2O3:Cr3+ can be used for white light‐emitting diode (LED) applications.  相似文献   

14.
This article reports a novel blue emission in a series of Ca12Al10.6Si3.4O32Cl5.4:Ce3+ phosphor under excitation in the near‐UV wavelength range. This phosphor was prepared using the combustion method. Here, the Ce3+ emission band is observed over a broad range of 380–550 nm, under 365 nm excitation, and is due to 5d–4f transition. The effect of a Li+ charge compensator on the emission properties of the phosphor was also investigated for the first time. X‐Ray diffraction confirmed the phase purity of the synthesized phosphor. The surface morphology and elemental composition of the phosphor were studied using scanning electron microscopy and energy‐dispersive X‐ray spectroscopy. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

15.
《Luminescence》2017,32(3):334-340
A series of Eu2+‐activated barium orthosilicates (BaZnSiO4) were synthesized using a high‐temperature solid‐state reaction. A photoluminescence excitation study of Eu2+ shows a broad absorption band in the range of 270–450 nm, with multiple absorption peak maxima (310, 350 and 400 nm) due to 4f–5d electronic transition. The emission spectra of all the compositions show green color emission (in the spectral region 450–550 nm with a peak maximum at 502 nm and a shoulder at ~ 490 nm) with appropriate Comission Internationale de l'Eclairage (CIE) color coordinates. The two emission peaks are due to the presence of Eu2+ in two different Ba sites in the BaZnSiO4 host lattice. The energy transfers between the Eu2+ ions in BaZnSiO4 host are elucidated from the critical concentration quenching data based on the electronic multipolar interaction. All Eu2+‐activated BaZnSiO4 phosphor materials can be efficiently excited in the ultraviolet (UV) to near UV‐region (270–420 nm), making them attractive candidate as a green phosphor for solid state lighting–white light‐emitting diodes.  相似文献   

16.
Frequency up‐conversion (UC) emission from the Nd3+‐Yb3+/Nd3+‐Yb3+‐Li+ co‐doped gadolinium oxide (Gd2O3) phosphors prepared by the solution combustion technique in the visible range have been studied by using 980 nm near infrared (NIR) laser diode excitation. The crystalline structure and formation of the cubic phase has been confirmed with the help of X‐ray diffraction (XRD) studies. XRD peak shifts have been found towards the lower diffraction angle side in the case of the Nd3+‐Yb3+‐Li+ co‐doped phosphors. Surface morphology and particle size information have been observed by using field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) analysis. Down‐conversion emission study under 351 nm excitation in the visible region for the Nd3+‐Yb3+/Nd3+‐Yb3+‐Li+ co‐doped phosphors has been performed. The UC emission bands lying in the green and red region arising from the Nd3+ ions have been enhanced by ~260 times, ~113 times due to incorporation of Li+ ions in the Nd3+‐Yb3+ co‐doped phosphors. Photometric characterization has been done for the Nd3+‐Yb3+/Nd3+‐Yb3+‐Li+ co‐doped phosphors. The present study suggests the capability of the synthesized phosphors in near‐infrared (NIR) to visible upconverter and luminescent device applications.  相似文献   

17.
Pure and Li+‐doped Alq3 complexes were synthesized by simple precipitation method at room temperature, maintaining the stoichiometric ratio. These complexes were characterized by X‐ray diffraction, ultraviolet‐visible absorption and Fourier transform infrared and photoluminescence (PL) spectra. X‐ray diffraction analysis reveals the crystalline nature of the synthesized complexes, while Fourier transform infrared spectroscopy confirm the molecular structure, the completion of quinoline ring formation and presence of quinoline structure in the metal complex. Ultraviolet‐visible and PL spectra revealed that Li+ activated Alq3 complexes exhibit the highest intensity in comparison to pure Alq3 phosphor. Thus, Li+ enhances PL emission intensity when doped into Alq3 phosphor. The excitation spectra lie in the range of 383–456 nm. All the synthesized complexes other than Liq give green emission, while Liq gives blue emission with enhanced intensity. Thus, he synthesized phosphors are the best suitable candidates for green‐ and blue‐emitting organic light emitting diode, PL liquid‐crystal display and solid‐state lighting applications. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

18.
Thermoluminescence (TL) materials are widely used in radiation measurements. The best‐known applications of TL materials are in the dosimetry of ionizing radiation, and in CTV screen phosphors, scintillators, X‐ray laser materials, etc. The TL glow curve and its kinetic parameters for annealed LaPO4 at different constant temperatures and for Dy3+‐doped LaPO4 phosphors irradiated by gamma‐rays are reported here. The samples were irradiated using a 60Co gamma‐ray source at a dose of 10 Gy and the heating rate used for TL measurements was 5ºC/s. The samples were characterized using X‐ray diffraction (XRD), Fourier transform infrared, transmission electron microscopy and TL techniques. The XRD pattern shows that the prepared phosphor has a good crystalline structure with an average crystallite size of ~ 18 nm. The samples show good TL peaks for 0.05, 0.1 and 0.2 mole % doping concentrations of Dy3+ ions and anneal above 400ºC. The TL glow curve characteristics of annealed LaPO4 and Dy3+‐doped LaPO4 were analyzed and trapping parameters calculated using various methods. All TL glow curves obey the second‐order kinetics with a single glow peak, which reveals that only one set of trapping parameter is set for a particular temperature. The TL sensitivity was found to depend upon the annealing temperature and Dy3+ doping concentration. The prepared sample may be a new nano phosphor and be useful in TL dosimetry. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

19.
The LaF3 nanocrystals through a facile hydrothermal route with hexagonal structures have been synthesized via doping of trivalent rare earth (RE3+) ions – RE = Tb, Sm, Dy and Tm – with rod‐like and perforated morphologies using NH4F as fluorine precursor. Hexagonal phase formation was confirmed by powder X‐ray diffraction. The crystalline sizes were calculated by the Scherrer equation where found to have an average crystalline size of 12 to 35 nm. The morphological studies of the nanocrystals were carried out by means of transmission electron microscopy (TEM). The LaF3:Tm3+,Sm3+ ions show the characteristic emission of Tb3+ and Tm3+ respectively. In Sm3+‐doped LaF3, three prominent emission peaks at 561, 597 and 641 nm were found, which belong to 4G5/2 → 6H5/2, 4G5/2 → 6H7/2 (magnetic dipole) and 4G5/2 → 6H9/2 (electric dipole) transitions, respectively. The Dy3+ activated LaF3 shows blue and yellow emission and the corresponding CIE color coordinate show white light emission (CCT value 10650 K).  相似文献   

20.
Aluminium oxide (Al2O3) has widely been used for catalysts, insulators, and composite materials for diverse applications. Herein, we demonstrated if γ‐Al2O3 was useful as a luminescence support material for europium (Eu) (III) activator ion. The hydrothermal method and post‐thermal treatment at 800°C were employed to synthesize Eu(III)‐doped γ‐Al2O3 nanofibre structures. Luminescence characteristics of Eu(III) ions in Al2O3 matrix were fully understood by taking 2D and 3D‐photoluminescence imaging profiles. Various sharp emissions between 580 to 720 nm were assigned to the 5D07FJ (J = 0, 1, 2, 3, 4) transitions of Eu(III) activators. On the basis of X‐ray diffraction crystallography, Auger elemental mapping and the asymmetry ratio, Eu(III) ions were found to be well doped into the γ‐Al2O3 matrix at a low (1 mol%) doping level. A broad emission at 460 nm was substantially increased upon higher (2 mol%) Eu(III) doping due to defect creation. The first 3D photoluminescence imaging profiles highlight detailed understanding of emission characteristics of Eu(III) ions in Al oxide‐based phosphor materials and their potential applications.  相似文献   

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