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1.
A novel Y3?xSi6N11: xCe3+ yellow phosphor was synthesized using the carbothermal reduction and nitridition method at 1550°C for 16 h in this letter. Photoluminescence spectra indicated that the phosphor showed broad excitation spectrum and had strong absorption in range of 350–450 nm. It also gave a broad emission band (Full width at half maximum = 153 nm) centered at 575 nm under 425‐nm excitation. With increasing Ce3+ concentration, the strongest emission intensity was obtained at 5 mol% Ce3+ doping amount and a systematic redshift was observed as the Ce3+ concentration increased. The results indicate that this novel yellow phosphor is a promising candidate for using in blue‐chip‐excited white light–emitting diodes (LEDs).  相似文献   

2.
A series of newly developed color‐tunable Ca3La6(SiO4)6: Ce3+, Tb3+ phosphors were successfully prepared in this study. The crystal structures of the prepared phosphors were revealed to be hexagonal with space group P63/m, and the lattice parameters were evaluated via utilizing the Rietveld refinement method. Upon excitation at 288 nm, the emission spectra of Ce3+and Tb3+ ions co‐doped Ca3La6(SiO4)6 phosphors included a blue emission band and several emission lines. The blue emission band with a peak at 420 nm originated in the fd transitions of Ce3+ ions, and the emission lines in the range of 450–650 nm were assigned to the 5D4 → 7FJ (J = 6, 5, 4, 3) transitions of Tb3+ ions. Increasing the doping content of Tb3+ ions considerably strengthened Tb3+ emission and reduced Ce3+ emission owing to the energy transfer from Ce3+ to Tb3+ ions. The mechanism of the energy transfer was confirmed to be a dipole–dipole interaction. The effective energy transfer from Ce3+ to Tb3+ ions caused a color shift from purplish‐blue to yellowish‐green. Color‐tunable Ca3La6(SiO4)6: Ce3+, Tb3+ phosphors have the potential to be utilized in light‐emitting diodes with proper modulation of the amount of Tb3+ ions.  相似文献   

3.
《Ceramics International》2016,42(9):10854-10865
Ce3+, Dy3+ and Ce3+/Dy3+ co-doped Ca20Mg3Al26Si3O68 (CMAS) nanophosphors were synthesized via modified solution-combustion method. Sharp X-ray diffraction patterns confirmed the formation of pure crystalline phase of Ca20Al26Mg3Si3O68 as an orthorhombic crystal system having space group Pmmn. The phase purity of as synthesized material has allowed reliable structural parameters to be obtained from the Rietveld analysis of its powder diffraction pattern. The Ce3+, Dy3+ and Ce3+/Dy3+ emission at different lattice sites in CMAS host has been identified and discussed. Under ultra-violet (UV) excitation, optical properties and the energy transfer mechanism from Ce3+ to Dy3+ in CMAS: Ce3+/Dy3+ nanophosphors have been elaborated by photoluminescence spectroscopy. Also, the effects of doping and sintering temperature on the structure of prepared CMAS host samples have been investigated in detail. The Ce3+/Dy3+ concentration quenching mechanism due to multipole–multipole interaction has been studied and the critical energy-transfer distance was calculated to be 7.8 Å. The band gap of the synthesized phosphors was calculated from diffuse reflectance spectra using the Kubelka–Munk function. A uniform layered structure network has been revealed in scanning electron microscopy images of the CMAS phosphor. Transmission electron microscopy results indicate nanocrystalline nature of synthesized phosphors. CMAS: 1 m% Ce3+ and CMAS: 0.5 m% Dy3+ nano-luminescent powders are promising candidate as a blue and blue–yellow emitting UV convertible phosphor for application in white light emitting diodes. By utilizing the energy transfer mechanism in present CMAS: Ce3+/Dy3+ nanophosphors, with an appropriate tuning of the activator content, these phosphors can exhibit great potential for white light emission, as single-emitting component phosphors in solid state lighting technology.  相似文献   

4.
Structural modification is an important means to induce redshift of Ce3+ emission in garnet phosphor. We intend to design and synthesize garnet oxynitride compounds which combine attributes of rigidity inherited from garnet structure and of high covalence characteristic of oxynitride compounds. However, impurity phase usually occurs in the nitridation of garnet phosphor, due to the low solubility of nitrogen in oxides. We herein exploit the cooperative cation substitution strategy to facilitate the incorporation of nitrogen in Y3Al5O12. It is found that partial substitution of Y3+‐Altet3+ pairs by Mg2+‐Si4+ pairs can diminish the phase instability caused by the replacement of Altet3+‐O2? by Si4+‐N3?. A novel pure garnet phase oxynitride phosphor MgY2Al3Si2O11N:Ce3+ with a higher substitution content of N has been obtained and the successful incorporation of N in the garnet phosphor is confirmed by the Rietveld refinements of XRD, XPS, and TEM. The emission and excitation spectra indicate that the blue‐light‐excitable MgY2Al3Si2O11N:Ce3+ phosphor exhibited a bright yellow‐orange emission peaking at 570 nm, which is redshifted by 28 nm when compared to YAG:Ce3+. The garnet oxynitride phosphor exhibit excellent thermal stability with high quantum efficiency and is a promising candidate for warm white LED.  相似文献   

5.
Ca3Sc2Si3O12:Ce3+ (CSS:Ce) green phosphors used for white light‐emitting diodes (LEDs) are synthesized and codoped with Al3+ via a solid‐state reaction method. The crystal structure and vibrational modes are analyzed by X‐ray diffraction, Fourier transform infrared spectroscopy, and Raman scattering spectroscopy. The energy transfer behavior and optical performance are characterized by photoluminescence and excitation spectra, quantum efficiency, and time‐resolved photoluminescence. The incorporation of Al3+ into CSS:Ce can inhibit the formation of the impurity phases Sc2O3 and CeO2, improve crystallinity, and enhance the photoluminescence intensity as well as quantum efficiency. The substitution of Sc3+ with Al3+ increased the crystal field splitting of Ce3+ and resulted in the red shift of photoluminescence. The results show that Ca3Sc2?xAlxSi3O12:Ce3+ has high quantum efficiency, making it a promising green phosphor that can be collocated with a commercial 450 nm blue LED and a red phosphor for solid‐state lighting applications.  相似文献   

6.
This article reports a low‐cost yellow‐emitting Y3Al5‐xBxO12‐xNx:Ce3+ phosphor with an enhanced luminescent intensity and excellent thermal stability for white light‐emitting diodes (LEDs). It was synthesized by a simple gas‐pressure sintering (GPS) process. The effect of B3+–N3? incorporation on the optical properties of Y3Al5O12:Ce3+ phosphor was investigated. The addition of appropriate amounts of boron nitride (BN) leads to a marked increase in photoluminescent intensity and a slight shift of its emission spectra toward the blue region, which is assigned to the improved crystallinity and increased particle size. Especially, the prepared oxynitride phosphor does not exhibit any thermal quenching under high temperature, and the emission intensity at 250°C even increases up to 175% of that measured at 20°C. Finally, the white LED flat lamp with luminous efficiency as high as 101 lm/W, color rendering index of 72, and correlated color temperature of about 6600 K is successfully realized by using YAG:Ce3+ phosphor doped with 0.5 molar ratio BN, which is acceptable and promising for general indoor illuminations to replace fluorescent or incandescent lamps.  相似文献   

7.
A new method for improving color rendering index (CRI) and low correlated color temperature (CCT) in high‐power white‐light‐emitting diodes (WLEDs) is proposed. We used a configuration of phosphor‐in‐glass (PIG) and studied light output changes with the increment in concentration of yellow‐emitting Y3Al5O12:Ce3+ (YAG:Ce3+) phosphor. The PIG was coupled on the top of blue‐light‐emitting diodes (LED) chip (465 nm). To compensate the lack of red emission in the phosphor, Eu3+‐doped tellurium glass with different europium content was employed as a red emitter. The suitable contents of YAG:Ce3+ and Eu3+ were 7.5 weight percent (wt%) and 3 mol percent (mol%), respectively. The CRI value went from 72 to 82, whereas the CCT was reduced from 24 933 to 6434 K. The proposed structure can improve CCT as well as CRI of WLEDs just by placing a glass on top.  相似文献   

8.
Novel blue‐green emitting Ce3+‐ and Tb3+‐activated K2CaP2O7 (KCPO) luminescent materials were synthesized via a solid‐state reaction method. X‐ray diffraction, luminescence spectroscopy, decay time, and fluorescent thermal stability tests have been used to characterize the prepared samples. The KCPO:Ce3+,Tb3+ luminescence spectra show broad band of Ce3+ ions and characteristic line of Tb3+ ion transition (5D47F5). The color variation in the light emitting from blue to green under UV excitation can be obtained by tailoring the Tb3+ content in KCPO:Ce3+. Besides, Ce3+ ions obviously intensify Tb3+ ion emission through an effective energy transfer process, which was confirmed from decay curves. The energy transfer efficiency was determined to be 82.51%. A resonant type mechanism via the dipole–quadrupole interaction can be proposed for energy transfer. As a whole, the KCPO:Ce3+,Tb3+ phosphor exhibits excellent performance in the range from 77 to 673 K, indicating the phosphors are highly potential candidates for solid‐state lighting.  相似文献   

9.
Developing a yellow phosphor with broadband emission covering more red-light areas is an effective approach to achieve high-quality solid-state lighting. In this study, a novel yellow-emitting nitride phosphor, Ca5Si2Al2N8:Ce3+, was successfully prepared at atmospheric pressure and lower temperatures (1300°C), and its structure-property relation was revealed using crystal refinement, photoluminescence (PL) spectra, time-resolved PL spectra, and density-functional theory calculations. The results demonstrate that Ca atoms occupy three different crystallographic sites in the lattice, which are substituted by Ce3+ to form multiple luminescence centers. Thus, Ca5Si2Al2N8:Ce3+ emits strong yellow light with a maximum peak at 585 nm and a wide emission band. Compared with YAG:Ce3+, Ca5Si2Al2N8:Ce3+ has a wider emission band with a FWHM of 150 nm, which can effectively cover the green and red areas. Moreover, the sample can be fully excited by a blue LED chip due to its broad excitation band. Notably, the Ca5Si2Al2N8's tight crystal structure composed of edge-sharing AlN4 and SiN4 tetrahedra pairs guarantee its thermochemical stability and quantum efficiency. Furthermore, Ca5Si2Al2N8:Ce3+ exhibits better thermal stability than YAG:Ce3+. The results indicate that Ca5Si2Al2N8:Ce3+ is a promising yellow phosphor for WLEDs.  相似文献   

10.
This work presents the ultraviolet–visible spectroscopic properties of Ba3Y2(BO3)4:Ce3+,Tb3+ phosphors prepared by a high‐temperature solid‐state reaction. Under ultraviolet light excitation, tunable emission from the blue to yellowish‐green region was obtained by changing the doping concentration of Tb3+ when the content of Ce3+ is fixed. The efficient energy transfer process between Ce3+ and Tb3+ ions was observed and confirmed in terms of corresponding excitation and emission spectra. In addition, the energy transfer mechanism between Ce3+ and Tb3+ was proved to be dipole–dipole interaction in Ba3Y2(BO3)4:Ce3+,Tb3+ phosphor. By utilizing the principle of energy transfer and appropriate tuning of Ce3+/Tb3+ contents, Ba3Y(BO3)4:Ce3+,Tb3+ phosphors can have potential application as an UV‐convertible phosphor for near‐UV excited white light‐emitting diodes.  相似文献   

11.
A series of phosphors Ca12(0.97?x)Al14O32F2: 0.03Ce3+, xTb3+ have been prepared by a hightemperature solid‐state reaction using boric acid as flux. These oxyfluorides crystallize in cubic structure, space group. Under the near ultraviolet excitation within wavelength range 310–390 nm, Ca12(0.97?x)Al14O32F2: 0.03Ce3+, xTb3+ phosphors exhibit an intense emission covering a broad band of 370–500 nm derived from the 5d→4f transitions of Ce3+ and a characteristic emission at 544 nm of Tb3+. The emission can be tuned from blue to green by altering the relative ratio of Ce3+ to Tb3+ in the composition. The energy‐transfer mechanism from Ce3+ to Tb3+ is investigated based on the site occupancy of the luminescence center in the crystal structure of the Ca12Al14O32F2 host. More importantly, when a certain amount of boric acid is added as flux in the synthesis, the fluorescence intensity of the phosphors increases about 65%. Because of its broad excitation and efficiently tunable blue to green luminescence, the Ca12(0.97?x)Al14O32F2: 0.03Ce3+, xTb3+ phosphors may find promising application as a near UV‐convertible phosphor for white‐light‐emitting diodes.  相似文献   

12.
《Ceramics International》2023,49(8):12491-12498
Developing an efficient broadband yellow phosphor with more red-light components and small thermal quenching is of great significance for solid-state lighting. In this study, a broadband yellow-emitting nitridoalumosilicate Ca4SiAl3N7:Ce3+ phosphor was successfully synthesized by a solid-phase method at comparatively low temperature (1350 °C) and normal pressure. The crystal structure and electronic structure of Ca4SiAl3N7 were studied using Rietveld refinement and density functional theory. The photoluminescence properties of the Ca4SiAl3N7:Ce3+ phosphor were studied, including excitation and emission spectra, time-resolved photoluminescence spectra and temperature-dependent emission spectra. The results show that the Ca4SiAl3N7:Ce3+ phosphor can be effectively excited by the blue chip and emit a strong broadband yellow light with maximum at 568 nm and the half width of 142 nm. Moreover, the Ca4SiAl3N7:Ce3+ phosphor exhibits good thermal stability, which can still maintain 75% and 68% of the strength at room temperature when at 150 °C and 200 °C, respectively, and without spectral shift. A warm WLED can be realized by combining Ca4SiAl3N7:Ce3+ yellow phosphor and blue LED chip. This study provides insights into developing novel broadband yellow nitridoalumosilicate phosphor with more red-light components, small thermal quenching and simple synthesis conditions.  相似文献   

13.
Ce3+, Nd3+ codoped (Sr0.6Ca0.4)3(Al0.6Si0.4)O4.4F0.6 phosphors were synthesized through the high‐temperature solid‐state reaction method. Luminescence spectra, absorption spectra, and decay lifetimes of these samples have been measured to prove the energy‐transfer process from Ce3+ to Nd3+. Under UV and blue light excitation, (Sr0.6Ca0.4)3(Al0.6Si0.4)O4.4F0.6:Ce3+,Nd3+ phosphors exhibit near‐infrared (NIR) emission, mainly peaking at 1093 nm and secondarily at 916 nm. The NIR emission matches well with the band gap of c‐Si. Results of this work suggest that the (Sr0.6Ca0.4)3(Al0.6Si0.4)O4.4F0.6:Ce3+, Nd3+ phosphors have potential application as down‐shifting luminescent convertor for enhancing the photoelectric conversion efficiency of c‐Si solar cell.  相似文献   

14.
Eu3+‐doped cesium barium borate glass with the composition of Cs2O·2BaO·3B2O3 was prepared by the conventional melt quenching method. The glass‐ceramic sample was obtained from the re‐crystallization of the as‐made glass to change the amorphous glass into a crystalline host. This reduces the Eu3+ in glass to Eu2+ ions resulting in a yellow‐emitting phosphor of Eu2+‐activated CsBaB3O6. The samples were investigated by the XRD patterns and SEM micrograph, the optical absorption, the photoluminescence spectra, and decay curves. The as‐made glass has only Eu3+ centers. Under the excitation of blue or near‐UV light, Eu2+‐doped CsBaB3O6 presents yellow‐emitting color from the allowed inter‐configurational 4f–5d transition in the Eu2+ ions. The maximum absolute luminescence quantum efficiencies of Eu2+‐doped CsBaB3O6 phosphor was measured to be 47% excited at 430 nm light at 300 K. By taking into account the efficient excitation in blue wavelength region, this new phosphor could be a potential yellow‐emitting phosphor for an application in white light‐emitting diodes fabricated with blue chips.  相似文献   

15.
In this study, Sr2+, Ca2+, Zn2+, and Mg2+ ions act to tune the emission band to the blue-cyan region in BaxSryB2O5:Ce3+ (BSBO), BaxCazB2O5:Ce3+ (BCBO), BaxZnuB2O5:Ce3+ (BZBO), and BaxMgvB2O5:Ce3+ (BMBO) phosphors. A red shift occurs with the increase of Sr2+, Ca2+, Zn2+, and Mg2+ concentration, and a blue shift occurs when the concentrations of Sr2+, Ca2+, Zn2+, and Mg2+ exceed the critical value. The emission color can be tuned from deep blue (0.15, 0.12) to cyan (0.16, 0.27) upon 365 nm UV lamp excitation due to the crystal field splitting and centroid shifts. The excitation band shift to long wavelength by introducing ions, so that the synthesized phosphor can be better matched with the n-UV chip. The emission intensity slowly decreases with the temperature increasing. Therefore, the BMBO:Ce3+, BZBO:Ce3+, BCBO:Ce3+, and BSBO:Ce3+ phosphors with relatively good thermal stability were synthesized, which could have potential applications in the n-UV white LEDs.  相似文献   

16.
A simple, one-step, and fast method based on exothermic reactions is described for synthesis of Tb3Al5O12:Ce phosphor. Light-emitting diodes (LEDs) were fabricated by depositing this phosphor on a blue chip. Photoluminescence and LED emission are compared with respective results for well-known YAG:Ce phosphor. A significant improvement in color rendering index (CRI) attributed to the red shift of Ce3+ emission was observed. Persistent emission is also reported for the first time in the Tb3Al5O12:Ce annealed in reducing atmosphere. It well correlates with Ce3+ emission and a peak around 80°C in the thermoluminescence glow. The long-lasting emission was associated with host-related electron traps.  相似文献   

17.
The resin-free YAG:Ce3+-Al2O3 eutectic ceramic phosphor for white light emitting diodes (WLEDs) was successfully grown in vacuum by Horizontal Directional Solidification method (HDS). X-ray diffraction and scanning electron microscopy indicate that this material has a typical eutectic structure of interpenetrating sapphire and garnet phases. The excitation spectra, emission spectra and temperature characteristics of the eutectic show that it is characterized by a wide excitation band and it has good stability in high temperature. In X-ray photoelectron spectroscopy, annealing in an air atmosphere could eliminate the oxygen vacancies and didn’t change the Ce3+ valence in the eutectic. The YAG:Ce3+-Al2O3 eutectic ceramic with different thickness was fixed in COB (chip on board) element for researching the performance of the WLEDs with the phosphor. The electroluminescence characterization of the WLEDs show that the WLEDs with the eutectic ceramic are more excellent than the common commercial WLEDs.  相似文献   

18.
Transparent glass‐ceramics containing Ce3+: Y3Al5O12 phosphors and Eu3+ ions were successfully fabricated by a low‐temperature co‐sintering technique to explore their potential application in white light‐emitting diodes (WLEDs). Microstructure of the sample was studied using a scanning electron microscope equipped with an energy dispersive X‐ray spectroscopy. The impact of co‐sintering temperature, Ce3+: Y3Al5O12 crystal content and Eu3+ doping content on optical properties of glass‐ceramics were systematically studied by emission, excitation spectra, and decay curves. Notably, the spatial separation of these two different activators in the present glass‐ceramics, where Ce3+ ions located in YAG crystalline phase while the Eu3+ ones stayed in glass matrix, is advantageous to the realization of both intense yellow emission assigned to Ce3+: 5d→4f transition and red luminescence originating from Eu3+: 4f→4f transitions. As a result, the quantum yield of the glass‐ceramic reached as high as 93%, and the constructed WLEDs exhibited an optimal luminous efficacy of 122 lm/W, correlated color temperature of 6532 K and color rendering index of 75.  相似文献   

19.
Ce3+ and Tb3+ co-doped Sr2B2O5 phosphors were synthesized by the solid-state method. X-ray diffraction (XRD) was used to characterize the phase structure. The luminescent properties of Ce3+ and Tb3+ co-doped Sr2B2O5 phosphors were investigated by using the photoluminescence emission, excitation spectra and reflectance spectra, respectively. The excitation spectra indicate that this phosphor can be effectively excited by near ultraviolet (n-UV) light of 317 nm. Under the excitation of 317 nm, Sr2B2O5:Ce3+,Tb3+ phosphors exhibited blue emission corresponding to the fd transition of Ce3+ ions and green emission bands corresponding to the ff transition of Tb3+ ions, respectively. The Reflectance spectra of the Sr2B2O5:Ce3+,Tb3+ phosphors are noted that combine with Ce3+ and Tb3+ ion absorptions. Effective energy transfer occurred from Ce3+ to Tb3+ in Sr2B2O5 host due to the observed spectra overlap between the emission spectrum of Ce3+ ion and the excitation spectrum of Tb3+ ion. The energy transfer efficiency from Ce3+ ion to Tb3+ ion was also calculated to be 90%. The phosphor Sr2B2O5:Ce3+,Tb3+ could be considered as one of double emission phosphor for n-UV excited white light emitting diodes.  相似文献   

20.
High-efficient Ce3+/Tb3+ co-doped Ba3Y2B6O15 phosphors with multi color-emitting were firstly prepared, and their structural and luminescent properties were studied by XRD Rietveld refinement, emission/excitation spectra, fluorescence lifetimes as well as temperature-variable emission spectra. Upon 365?nm excitation, the characteristic blue Ce3+ band along with green Tb3+ peaks were simultaneously found in the emission spectra. Moreover, by increasing concentration of Tb3+, a blue-to-green tunable emitting color could be realized by effective Ce3+→Tb3+ energy transfer. Furthermore, all Ba3Y2B6O15: Ce3+, Tb3+ phosphors exhibit high internal quantum efficiency of ~?90%, while the temperature-variable emission spectra reveal that the phosphors possess impressive color stability as well as good thermal stability (T50 =?~?120?°C). The results indicate that these efficient color-tuning Ba3Y2B6O15: Ce3+, Tb3+ might be candidate as converted phosphor for UV-excited light-emitting diodes.  相似文献   

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