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1.
In this study, red phosphors Ca1?n Mg n TiO3:Eu3+,Bi3+ were prepared by the sol?Cgel method and the impact of single dopant, co-dopants and solid solutions on the photoluminescence of the samples has been also investigated. Our results show that the crystal structure of the host does not have distinct changes when doped with Eu3+, Bi3+ and/or Mg2+. The emission intensity at 615?nm of Eu3+ increased at the presence of Bi3+ ions owing to the energy transfer from Bi3+ ion to Eu3+ ion. Moreover, with the addition of Mg2+, the red emission of the phosphor was further enhanced due to the stronger absorption at 399 and 467?nm, which match well with the emission of near-UV (395?C400?nm) and blue-LED (450?C470?nm), respectively. Under the near-UV (399?nm) or blue light (467?nm) excitation, the fluorescence quantum yield of the optimal composition Ca0.9Mg0.1TiO3:0.18Eu3+,0.018Bi3+ is 0.36 and 0.41, respectively, which possesses the higher photoluminescence intensity than CaMoO4:0.2Bi3+,0.05Eu3+ and the commercially available Y2O2S:Eu3+ phosphors under near-UV excitation. Based on these results, we are currently considering the potential application of Ca0.9Mg0.1TiO3:Eu3+,Bi3+ as a near-UV or blue-chip convertible red-emitting phosphor.  相似文献   

2.
Developing highly efficient cyan-emitting fluorescent materials is essential to bridge the cyan gap in phosphor-converted white light-emitting diodes for full-spectrum white illumination. Here, a Bi-doped cyan phosphor has been reported to solve this gap. The phase purity, photoluminescence emission/excitation spectra, concentration quenching, lifetime decay curves, and temperature-dependent photoluminescence emission spectra were systematically investigated. SrLaGaO4:Bi3+ exhibits a broad excitation band (250–400 nm), which matches with the emission of a commercial near-ultraviolet light-emitting diode chip. The cyan light peaked at 475 nm is observed, which is attributed to the 3P11S0 transition of Bi3+. The thermal quenching experiment was performed, and the activation energy was calculated as 0.36 eV. Finally, full-spectrum white light-emitting diode devices were fabricated using SrLaGaO4:Bi3+ phosphors, commercial blue BaMgAl10O17:Eu2+ phosphor, green (Ba, Sr)2SiO4:Eu2+ phosphor, and red CaAlSiN3:Eu2+ phosphor, which displayed an International Commission on an illumination coordinate of (0.3732, 0.3850), a correlated color temperature of 4290 K, and a color rendering index of 93.2 at a drive current of 20 mA. This result indicates that SrLaGaO4:Bi3+ plays an essential role in bridging the cyan gap, providing new inspiration for applying cyan-emitting phosphors in full-spectrum white lighting.  相似文献   

3.
Green-light-emitting long-lasting phosphorescence phosphor, Eu2+ activated calcium magnesium chlorosilicate Ca8Mg(SiO4)4Cl2, has been prepared by a modified solid-state reaction method using Ca2SiO4:Eu2+ as a precursor. Its properties have been discussed and analyzed utilizing XRD, photoluminescence, excited-state decay curve and long-lasting phosphorescence decay curve. Upon UV light excitation, the emission spectrum of Ca8Mg(SiO4)4Cl2:Eu2+ phosphor is composed of two separate bands centered at 425 nm and 505 nm, respectively. Furthermore, after irradiation by a 320-nm UV light for 3 min, the 2% Eu2+-doped Ca8Mg(SiO4)4Cl2 phosphor emits intense green-light-emitting afterglow from the 4f65d1→4f7 transition of Eu2+, and its afterglow can be seen with the naked eye in the dark clearly for more than 3 h after removal of the excitation source. The disappearance of the high-energy 425 nm band in the afterglow emission spectrum is explained by its different crystallographic sites. The afterglow decay curve of the Eu2+-doped Ca8Mg(SiO4)4Cl2 phosphor contains a fast decay component and another slow decay one. The possible mechanism of this long-lasting phosphorescence phosphor is also discussed based on the experimental results.  相似文献   

4.
A series of Eu3+ ions co-doped (Gd0.9Y0.1)3Al5O12:Bi3+, Tb3+ (GYAG) phosphors have been synthesized by means of solvothermal reaction method. The XRD pattern of GYAG phosphor sintered at 1500 °C confirms their garnet phase. The luminescence properties of these phosphors have been explored by analyzing their excitation and emission spectra along with their decay curves. The excitation spectra of the GYAG:Bi3+, Tb3+, Eu3+ phosphors consists of broad bands in the shorter wavelength region due to 4f8 → 4f75d1 transition of Tb3+ ions overlapped with 6s2 → 6s16p1 (1S0 → 3P1) transition of Bi3+ ions and the charge transfer band of Eu3+–O2?. The present phosphors exhibit green and red colors due to 5D4 → 7F5 transition of Tb3+ ions and 5D0 → 7F1 transition of Eu3+ ions, respectively. The emission was shifted from green to red color by co-doping with Eu3+ ions, which indicate that the energy transfer probability from Tb3+ to Eu3+ ions are dependent strongly on the concentration of Eu3+ ions.  相似文献   

5.
A series of yellow-emitting oxynitride Ca0.65Si10Al2O0.7N15.3:xEu2+ phosphors with α-sialon structure were synthesized. The phase composition and crystal structure were identified by X-ray diffraction and the Rietveld refinement. The excitation and emission spectra, reflectance spectra and thermal stability were investigated in detail, respectively. Results show that Ca0.65Si10Al2O0.7N15.3:0.12Eu2+ phosphors can be efficiently excited by UV-Vis light in the broad range of 290–450 nm and exhibit broad emission spectra peaking at 550–575 nm. The concentration quenching mechanism are discussed in detail and determined to be the dipole-dipole interaction. When the temperature increased to 150 °C, the emission intensity of Ca0.65Si10Al2O0.7N15.3:0.12Eu2+ phosphor is 88.46% of the initial value at room temperature. White LED was fabricated with N-UV LED chip combined with blue Ca3Si2O4N2:Ce3+ and yellow Ca0.65Si10Al2O0.7N15.3:Eu2+ phosphors. The color rendering index and correlated color temperature of this white LED were measured to 78.94 and 6728.12 K, respectively. All above results demonstrate that the as-prepared Ca0.65Si10Al2O0.7N15.3:xEu2+ may serve as a potential yellow phosphor for N-UV w-LEDs.  相似文献   

6.
Eu3+ luminescence is studied in apatite-related phosphate BiCa4(PO4)3O. Compositions of the formula Bi1−xEuxCa4(PO4)3O [x=0.05, 0.1, 0.3, 0.5, 0.8 and 1.0] are synthesized and they are isostructural with parent BiCa4(PO4)3O. Room temperature photoluminescence shows the various transitions 5D07FJ(=0,1,2) of Eu3+. The emission results of compositions with different Eu3+ content show the difference in site occupancy of Eu3+ in Bi1−xEuxCa4(PO4)3O. The intense 5D0-7F0 line at 574 nm for higher Eu3+ content is attributed to the presence of strongly covalent Eu-O bond that is possible by substituting Bi3+ in the Ca(2) site. This shows the preferential occupancy of Bi3+ in Ca(2) site and this has been attributed to the 6s2 lone pair electrons of Bi3+. This is further confirmed by comparing the emission results with La0.95Eu0.05Ca4(PO4)3O.  相似文献   

7.
Motivated by the need for new phosphors of white light emitting diode (WLED) application, Ca0.95Nb2 O6:Eu3+0.05 phosphors were synthesized by high temperature solid‐state reaction. Increasing the content of doped‐Eu3+ and adding the co‐activator Bi3+ to improve the photoluminescence (PL) intensity of Ca1?xNb2 O6Eu3+x phosphors were investigated in detail. The effects of Eu3+ were better than that of Bi3+ on the PL intensity of Ca1?xNb2 O6Eu3+x phosphors. Compared with Y2O2 S:0.05Eu3+ the Ca0.70Nb2 O6:Eu3+0.03 phosphor could be excited efficiently by UV (395 nm) light and emit the red light at 614 nm with line spectra, which were coupled well with the characteristic emission from UV‐Near UV LED. The CIE (International Commission on Illumination) chromaticity coordinates (x?0.654, y?0.348) of Ca0.70Nb2O6:Eu3+0.03 were close to the NTSC (National Television Standard Committee) standard values. Therefore Ca0.70Nb2 O6:Eu3+0.03 might find application to UV‐Near UV InGaN chip‐based white light emitting diodes, which is further proved by the LED fabrication with the Ca0.70Nb2 O6:Eu3+0.03 phosphor.  相似文献   

8.
As an Hg-free lamp using phosphor, the Bi^3+ and EH^3+ co-doped Y2O2S phosphors were prepared and their luminescence properties under vacuum ultraviolet(VUV) excitation were investigated. The VUV photoluminescent intensity of Y2O2S:Eu^3+ was weak, however, considerably stronger red emission at 626 nm with good color purity was observed in Y2O2S:Eu^3+,Bi^3+ systems. Investigation on the photoluminescence reveals that the strong VUV luminescence of Y2O2S:Eu^3+,Bi^3+ at 147 nm is mainly because the Bi^3+ acts as a medium and effectively performs the energy transfer process: Y^3+-O^2-→Bi^3+→Eu^3+, while the intense emission band at 172 nm is attributed to the absorption of the characteristic ^1So-^1P1 transition of Bi^3+ and the direct energy transfer from Bi^3+ to Eu^3+. The Y2O2S:Eu^3+,Bi^3+ shows excellent VUV optical properties compared with the commercial (Y,Gd)BO3:Eu^3+. Thus, the Y2O2S:Eu^3+,Bi^3+ can be a potential red VUV-excited candidate applied in Hg-free lamps for backlight of liquid crystal display.  相似文献   

9.
A novel red emitting phosphor, Eu3+-doped Ca2SnO4, was prepared by the solid-state reaction. X-ray powder diffraction (XRD) analysis confirmed the formation of Ca2SnO4: Eu3+. Field-emission scanning electron-microscopy (FE-SEM) observation indicated a narrow size-distribution of about 500 nm for the particles with spherical shape. Photoluminescence measurements indicated that the phosphor exhibits bright red emission at about 615 nm under UV excitation. The excellent luminescence properties make it possible as a good candidate for plasma display panels (PDP) application. Splitting of the 5D0-7FJ transitions of Ca2SnO4: Eu3+ suggests that the Eu3+ ions occupied two nonequivalent sites in the crystallite. The luminescence lifetime measurement showed a bi-exponential decay, providing other evidence for the existence of two different environments for Eu3+ ions.  相似文献   

10.
A series of orange-red emitting phosphor Y(PO3)3: xEu3+ (x = 0.1–1.0) was prepared by a solid-state reaction route. The phosphors were characterized by X-ray diffraction (XRD) and photoluminescence (PL) as well as decay lifetimes. Studies revealed the phase transfer from monoclinic to orthorhombic when Y3+ is totally replaced by Eu3+, and expansion of the unit cell occurs with increasing Eu3+ doped content. The PL spectra show that the phosphors Y(PO3)3: xEu3+ can be effectively excited by near ultraviolet (n-UV) light, and exhibit strong red-orange emission with no concentration quenching. The profile of PL spectra changes significantly at high Eu3+ content (x ≥ 0.80), which is due to the variation of preference for substitution of Eu3+. The luminescence due to the 5D0 → 7FJ (J = 1, 2) transitions at 77 K exhibits its own spectral features for different crystallographic site. It is found that Eu3+ ions occupy the centers of octahedral polyhedron and form Ci/C1 point group in Y(PO3)3.  相似文献   

11.
Low‐dimensional ns2‐metal halide compounds have received immense attention for applications in solid‐state lighting, optical thermometry and thermography, and scintillation. However, these are based primarily on the combination of organic cations with toxic Pb2+ or unstable Sn2+, and a stable inorganic luminescent material has yet to be found. Here, the zero‐dimensional Rb7Sb3Cl16 phase, comprised of isolated [SbCl6]3? octahedra and edge‐sharing [Sb2Cl10]4? dimers, shows room‐temperature photoluminescence (RT PL) centered at 560 nm with a quantum yield of 3.8±0.2 % at 296 K (99.4 % at 77 K). The temperature‐dependent PL lifetime rivals that of previous low‐dimensional materials with a specific temperature sensitivity above 0.06 K?1 at RT, making it an excellent thermometric material. Utilizing both DFT and chemical substitution with Bi3+ in the Rb7Bi3?3xSb3xCl16 (x≤1) family, we present the edge‐shared [Sb2Cl10]4? dimer as a design principle for Sb‐based luminescent materials.  相似文献   

12.
Yellow/orange-emitting nitrogen-rich Ca0.9Si9Al3(O,N)16: Eu2+ phosphors were successfully prepared by solid-state reaction synthesis. The fluorescence excitation spectra of all of the nitrogen-rich Ca0.9Si9Al3(O,N)16: Eu2+ phosphor powders displayed two broad bands centered at about 300 nm and 400–475 nm. The first peak was assigned to the absorption of the host lattice and the second to the 4f7 → 4f65d1 absorption of the Eu2+ ions, its means enhanced 4f7 → 4f65d excitation of Eu2+ ion. The absorption peak intensity increased upon increasing the Eu2+ doping amount, but only up to a Eu2+ concentration ratio of 0.15. The emission spectra of the prepared Ca0.9Si9Al3(O,N)16: Eu2+ phosphors all exhibited a single broad band in the 500–700 nm region, maximum emission peak observed at 591 nm. The room temperature decay times were observed τ1 = 1.27 μs and τ2 = 9.90 μs.  相似文献   

13.
Strong orange-red-emitting Ba2LaTaO6:Eu3+ phosphors were designed and applied in various optical applications of luminescence lifetime thermometer, anti-counterfeiting film, and solid-state lighting applications. The crystal structure, elemental composition, asymmetry ratio, and other luminescent behaviors were investigated in detail. Especially, the optimal Ba2LaTaO6:0.1Eu3+ phosphor presented remarkable quantum yield (45.29%) and thermal stability (71.52% at 423 K). Based on the temperature-dependent luminescence decay curves, the maximum relative sensing sensitivity was 0.185 × 10?2 K?1 at 513 K. In addition, a novel anti-counterfeiting technique was introduced. The fabricated polydimethylsiloxane films exhibited three different colors under the irradiations of room light, 254 nm light, and 365 nm light, respectively. Eventually, the packaged light-emitting diode displayed the pure orange-red emission. Briefly, a series of the Eu3+-activated Ba2LaTaO6 phosphors with excellent luminescent properties were characterized and further applied in several optical fields for the first time.  相似文献   

14.
We present an efficient way to search a host for ultraviolet (UV) phosphor from UV nonlinear optical (NLO) materials. With the guidance, Na3La2(BO3)3 (NLBO), as a promising NLO material with a broad transparency range and high damage threshold, was adopted as a host material for the first time. The lanthanide ions (Tb3+ and Eu3+)-doped NLBO phosphors have been synthesized by solid-state reaction. Luminescent properties of the Ln-doped (Ln=Tb3+, Eu3+) sodium lanthanum borate were investigated under UV ray excitation. The emission spectrum was employed to probe the local environments of Eu3+ ions in NLBO crystal. For red phosphor, NLBO:Eu, the measured dominating emission peak was at 613 nm, which is attributed to 5D0-7F2 transition of Eu3+. The luminescence indicates that the local symmetry of Eu3+ in NLBO crystal lattice has no inversion center. Optimum Eu3+ concentration of NLBO:Eu3+ under UV excitation with 395 nm wavelength is about 30 mol%. The green phosphor, NLBO:Tb, showed bright green emission at 543 with 252 nm excited light. The measured concentration quenching curve demonstrated that the maximum concentration of Tb3+ in NLBO was about 20%. The luminescence mechanism of Ln-doped NLBO (Tb3+ and Eu3+) was analyzed. The relative high quenching concentration was also discussed.  相似文献   

15.
In the current study, novel hexagonal rods based on Bi0.4Sb1.6Te3 raw materials and dispersed with x amounts of Se (x = 0.0, 0.2, 0.4, 0.6, 0.8, and 1.0) in the form Bi0.4Sb1.6Se3xTe3(1−x) were synthesized via a standard solid-state microwave route. The morphologies of these rods were explored using field emission scanning electron microscopy (FESEM). The crystalline of the powders were examined by X-ray diffraction (XRD), which showed that the powders of 0.0 ≤ x ≤ 0.8 samples can be indexed as the rhombohedral phase, whereas the sample with x = 1.0 has an orthorhombic phase structure. The influence of variations in Se content on thermoelectric properties was studied in the temperature range of 300–523 K. The alloying of Se in Bi0.4Sb1.6Te3 effectively caused a decrease in hole concentration and, thus, a decrease in electrical conductivity and an increase in Seebeck coefficient. The maximal power factor measured in the present work was 7.47 mW/m K2 at 373 K for the x = 0.8 sample.  相似文献   

16.
Y4MgSi3O13:Bi3+, Eu3+ nanophosphors have been prepared by a facile sol–gel method. The products have been characterized by X-ray diffraction, field-emission scanning electron microscopy and fluorescence measurements. The results show that the nanophosphors are of single phase hexagonal Y4MgSi3O13 with size-distribution of 50–90 nm in diameter. White-light emission has been obtained from Bi3+ and Eu3+ co-doped Y4MgSi3O13 nanophosphors upon excitation of 350 nm ultraviolet light. It is noted that Bi3+ ions can occupy two different Y3+ sites and generate different emissions from the 3p1 → 1s0 transition. Warm white light has been obtained from Y4MgSi3O13:Bi3+, Eu3+ nanophosphors according to Commission International de I’Eclairage (CIE) chromaticity coordinates and color temperature (Tc) with appropriately adjusted contents of Bi3+ and Eu3+. The results indicate that Y4MgSi3O13:0.08Bi3+, 0.04Eu3+ (x = 0.31, y = 0.31, Tc = 6907 K) are potential nanophosphors for white light-emitting diodes (LEDs) applications.  相似文献   

17.
Motivated by the need for new red phosphors for solid-state lighting applications Eu3+-doped ZnMoO4 was prepared by solid-state reaction and its photoluminescence properties were investigated. Compared with Ca0.80MoO4:Eu0.203+, the obtained Zn0.80MoO4:Eu0.203+ phosphor shows a stronger excitation band near 400 nm as well as enhanced red emissions (under 393 nm excitation). The strong red-emission lines at 616 nm correspond to the forced electric dipole 5D07F2 transitions on Eu3+. The chromaticity coordinates (x=0.63, y=0.37) are close to the standard of National Television Standard Committee (NTSC). The optical properties suggest that Zn0.80MoO4:Eu0.203+ is an efficient red-emitting phosphor for LED applications.  相似文献   

18.
The spherical mesoporous MCM-41 coated with a novel Ca2MoO5:Eu3+ phosphor layer was prepared for the first time. The obtained Ca2MoO5:Eu3+-MCM-41 was characterized via XRD and FT-IR. The crystal system of the Ca2MoO5 phase was determined to be orthorhombic, and its space group was found to be Ima2 (46), and its cell parameters were a = 16.175, b = 5.1514, c = 5.6977 A°; α = β = γ = 90°. The particle dimensions of MCM-41 and Ca2MoO5:Eu3+-MCM-41 nanoparticles were determined to be 260 nm and 229 nm via scanning electron microscopy analysis. Bortezomib was loaded into the Ca2MoO5:Eu3+-MCM-41 nanoparticles under scCO2 at 200 bars and 40 °C. The results of the TG analysis showed that the amount of drug-loaded to MCM-41 and Ca2MoO5:Eu3+-MCM-41 nanoparticles were determined to be 14.02% and 3.02%, respectively. The BET analysis showed that while the specific surface area and pore volume of MCM-41 and Ca2MoO5:Eu3+ before Bortezomib (BTZ) loading were 1,506 m2/g and 267 m2/g, respectively, after drug loading these values were found to decrease to 488 m2/g and 7.883 m2/g. It was determined that BTZ was released from the nanoparticles in a sustained manner over 66 h. The R2 value, which was calculated to be 0.9739, indicated that the release kinetic of BTZ followed the Korsmeyer–Peppas model.  相似文献   

19.
The luminescence of several Sb3+-activated rare earth orthoborates (LnBO3Sb3+; Ln = Sc, Y, La, Gd, Lu) are reported. In all compositions the Stokes shift of the Sb3+ luminescence is rather large, resulting in rather low quenching temperatures (200 K or lower). The Stokes shift appears to be dependent on the coordination number and on the radius of the host lattice cation. This is explained from the assumed tendency of the Sb3+ ion to occupy an off-center position which becomes more apparent when the space available for the Sb3+ ion increases. The present results are compared with those on LnBO3Bi3+. It appears that the Stokes shift of the Bi3+ luminescence is more sensitive to the host lattice and is smaller than the Stokes shift of the Sb3+ luminescence. This is explained by the large radius of the Bi3+ ion compared to the Sb3+ ion. In GdBO3Sb3+ thermally activated energy transfer is observed from Gd3+ to Sb3+.  相似文献   

20.
Eu3+, Dy3+ and Dy3+/Eu3+ doped CdO-GeO2-TeO2 glasses were prepared using the melt-quenching process and analyzed by X-diffraction, Raman spectroscopy, excitation and emission spectra, and emission decay time profiles. The lack of X ray diffraction peaks revealed that all samples are amorphous. Vibrational modes associated with TeOTe and GeOGe related bonds and molecular oxygen were detected by Raman spectroscopy. The luminescence characteristics were studied upon excitations that correspond with the emission of InGaN (370–420 nm) based LEDs. The Eu3+ singly doped glass displayed reddish-orange global emission, with x = 0.601 and y = 0.349 CIE1931 chromaticity coordinates, upon 393 nm excitation. Neutral emission with x = 0.373 and y = 0.412 CIE1931 chromaticity coordinates and correlated color temperature (CCT) of 4400 K, was achieved in the Dy3+ singly doped glass excited at 388 nm. The Dy3+/Eu3+ co-doped glass exhibited warm, neutral and soft warm white emissions with CCT values of 3435, 4153 and 2740 K, under excitations at 382, 388 and 393 nm, respectively, depending mainly on the Dy3+ and Eu3+ relative excitation. The Dy3+ excitation bands observed in the Dy3+/Eu3+ glass by monitoring the 611 nm Eu3+ emission, suggest that Dy3+ → Eu3+ energy transfer takes place, despite the fact that the Dy3+ emission decays in the Dy3+ and Dy3+/Eu3+ doped glass, remain without changes. The shortening of Eu3+ decay in presence of Dy3+ was attributed to an Eu3+ → Dy3+ non-radiative energy transfer process, which according with the Inokuti-Hirayama model might be dominated through an electric quadrupole-quadrupole interaction, with efficiency and probability of 5.5% and 51.6 s−1, respectively.  相似文献   

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