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1.
Eu2+, Mn2+ doped Sr1.7Mg0.3SiO4 phosphors were prepared by high temperature solid-state reaction method. Their luminescence properties were studied. The emission spectra of Eu2+ singly doped Sr1.7Mg0.3SiO4 consist of a blue band (455 nm) and a green band (550 nm). The relative intensities of two emissions varied with Eu2+ concentration. Eu2+ and Mn2+ co-doped Sr1.7Mg0.3SiO4 phosphors emit three color lights and present whitish color. The blue (455 nm) and green (550 nm) emissions are attributed to the transitions of Eu2+, while the red (670 nm) emission is originated from the transition of Mn2+ ion. The results indicate the energy transfer from Eu2+ to Mn2+. The mechanism of the energy transfer is resonance-type energy transfer due to the spectral overlap between the emission of Eu2+and the absorption of Mn2+.  相似文献   

2.
《Ceramics International》2016,42(15):16817-16821
Novel double-perovskite Sr2ZnWO6:Mn4+(SZW:Mn4+) phosphor is synthesized by high-temperature solid-state reaction method in air. SZW:Mn4+ phosphor with excitation at 325 and 526 nm emits deep-red light, the chromaticity coordinate is (0.7315,0.2685), and the emission band peaking at ~702 nm within the range 640–760 nm is assigned to the 2E→4A2 transition of Mn4+ ion. The influences of “Mn4+- ligand” bonding and crystal field strength to emission properties of Mn4+ ion are analyzed. The optimal Mn4+ ion concentration in SZW:Mn4+ phosphor is ~0.8 mol%. Lifetime of SZW:Mn4+ phosphor decreases from 554.77 to 401.35 μs with increasing Mn4+ ion concentration in the range of 0.2–1.0 mol%. The lifetime data and decay curves indicate that there is only a single type of Mn4+ ion luminescent center in SZW:Mn4+ phosphor. The luminous mechanism of SZW:Mn4+ phosphor is analyzed by Tanabe-Sugano energy level diagram of Mn4+ in the octahedron together with the simple energy level diagram. The experimental results are helpful to research the influences of the neighboring coordination environment around Mn4+ and host crystal structure to the luminescence properties of Mn4+ ion and to deeply understand other Mn4+-dopedmaterials.  相似文献   

3.
《Ceramics International》2016,42(16):18324-18332
A series of Eu2+-activated novel phosphor-silicate apatite Sr3LaNa(PO4)2SiO4 phosphors were synthesized by solid-state reaction. The X-ray diffraction (XRD) and Rietveld refinement, diffuse reflectance spectra, luminescent spectra, decay curves and thermal quenching properties were applied to characterize the obtained phosphors. The XRD result revealed that all the samples possessed only a single phase with hexagonal structure and the doping of Eu2+ ions were successfully incorporated into the crystal lattice. The reflectance spectra showed an obvious red-shift of the wavelength from 400 to 700 nm with increasing Eu2+ ion concentration. The three different crystallographic sites of Eu2+ ions had been confirmed by their lifetimes. All the samples exhibited broad absorption bands from 200 to 450 nm, revealing the phosphor-silicate phosphor interesting for application in the near-UV used phosphor-converted LED chips. These results suggested that the Eu2+-activated phosphor-silicate Sr3LaNa(PO4)2SiO4 phosphors have the potential for near-UV pumped white-light-emitting diodes (w-LEDs).  相似文献   

4.
CdSiO3: Mn2+, Tb3+ long-lasting phosphor was prepared by the conventional high temperature solid-state method. Effects of the content of Mn2+ and Tb3+ on the luminescent properties of phosphor CdSiO3: Mn2+, Tb3+ were investigated by means of photoluminescence (PL) spectra, the afterglow intensity decay curves and the thermoluminescence (TL) spectra. It was found that when the Mn2+ and Tb3+ dopant-concentrations were 0.4 mol% and 0.8 mol% of Cd2+ ions in CdSiO3, respectively, the luminescence of phosphor prepared had better luminescent property and longer afterglow time. Role of Tb3+ co-doped into CdSiO3: Mn2+ matrix was discussed in this paper.  相似文献   

5.
《Ceramics International》2017,43(12):9084-9091
This paper reports the preparation of Eu3+ doped Gadolinium oxyorthosilicate (Gd2SiO5:Eu3+) phosphor with different concentration of Eu3+(0.1–2.5 mol%) using the modified solid state reaction method. The synthesis procedure of the Gd2SiO5:Eu3+phosphor using inorganic materials such as Gd2O3, silicon dioxide (SiO2), europium oxide (Eu2O3) and boric acid (H3BO3) as flux is discussed in detail. The prepared phosphor samples were characterized by using X-Ray Diffraction (XRD), Field Emission Gun Scanning Electron Microscopy (FEGSEM), Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR), Photoluminescence (PL) and Thermoluminescence (TL). The Commission Internationale de l′Eclairage(CIE) coordinates were also calculated. The PL emission was observed in the 350–630 nm range for the Gd2SiO5:Eu3+ phosphor. PL excitation peaks were observed at 266, 275, 312 and 395 nm while the emission peaks were observed at 380, 416, 437, 545, 579, 589, 607, 615 and 628 nm. The emission peak at 615 nm was the most intense peak for all the different Eu3+ concentration samples. From the XRD data, using the Scherrer's formula, the average crystallite size of the Gd2SiO5:Eu3+ phosphor was calculated to be 33 nm. TL was carried out for the phosphor after both UV and gamma irradiation. The TL response of the Gd2SiO5:Eu3+ phosphor for the two different radiations was compared and studied in detail. It was found that the present phosphor can acts as a single host for red emission (1.5 mol%) for display devices and light emitting diode (LED) and white light emission for Eu3+(0.1 mol%) and it might be used as a TL dosimetric material for gamma dose detection.  相似文献   

6.
《Ceramics International》2017,43(5):4440-4449
A series of size controllable Tb3+ and/or Eu3+ activated nano-sized silica phosphors have been successfully synthesized through a facile sol-gel method. The structure, morphology, compositions, and luminescence properties of as-prepared samples were well investigated using X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) and photoluminescence spectroscopy (PL). The results showed that all as-prepared samples were spherical nanoparticles but the sizes reduced gradually with the temperature increased from 25 °C to 65 °C, which was contrary to the BET surfaces as well as the luminescence intensity. Under ultraviolet excitation, the SiO2:Ln3+(Ln=Eu, Tb) spherical nanoparticles showed characteristic red and green emissions corresponding to f-f transition of Eu3+ and Tb3+, respectively. Moreover, the luminescence emissions of samples can be tuned from green to yellow, orange and red by co-doping the Tb3+ and Eu3+ ions in different concentration ratio into the SiO2 host due to the efficient dipole–dipole energy transfer mechanism from Tb3+ to Eu3+ under 377 nm excitation. These results show that as-prepared phosphors may find potential applications in color display fields.  相似文献   

7.
New transparent and high infrared reflection films having the sandwich structure of SiO2/Al:ZnO(AZO)/SiO2 were deposited on the soda-lime silicate glass at room temperature by radio frequency (R.F.) magnetron sputtering. The optical and electrical properties of SiO2 (110 nm)/AZO (860 nm)/SiO2 (110 nm) sandwich films were compared with those of single layer AZO (860 nm) films and double layer SiO2 (110 nm)/AZO (860 nm) films. The results show that these sandwich films exhibit high transmittance of over 85% in the visible light range (380–760 nm), and low reflection rate of below 4.5% in the wavelength range of 350–525 nm, which is not shown in the conventional single layer AZO (860 nm) films and double layer SiO2 (110 nm)/AZO (860 nm) films. Further these sandwich films display a low sheet resistance of 20 Ω/sq by sheet resistance formula and high infrared reflection rate of above 80% in the wavelength range of 15–25 μm. In addition, the infrared reflection property of these sandwich films is determined mainly by the AZO film. The outer SiO2 film can diminish the interference coloring and increase transparency; the inner SiO2 film improves the adhesion of the coating to the glass substrate and prevents Ca2+ and Na+ in the glass substrate from entering the AZO film.  相似文献   

8.
ZnGa2O4 phosphors were prepared by both SCM (solution combustion method) and SSRM (solid state reaction method). The properties of the both ZnGa2O4 phosphors were investigated by TGA (Thermogravimetric analysis), SEM (scanning electron microscope), BET (Brunauer Emmett Teller), PL (photoluminescence) and XRD (X-ray diffraction). The particle size of SCM phosphor was about one-hundredth of SSRM phosphor. The PL intensity of SCM phosphor was about 1.5-fold higher than that of SSRM phosphor. The SCM phosphor was also tried to be doped with Mn2+ ions. The highest PL peak was observed with Mn2+ ions of 0.003 mol fraction. The peak was shifted from blue (470 nm) to green (513 nm) color. These results might be very useful for high efficiency phosphors for displays such as field emission displays and plasma display panels.  相似文献   

9.
SiO2 reinforced with both multi-wall carbon nanotubes (MWCNTs) and ZnO particles was prepared. Owing to the consumption of an amorphous carbon layer on the outer surface of MWCNTs and the generation of oxygen vacancies in ZnO during sintering, the contact resistance between MWCNTs is lowered and a higher concentration of charge carriers is produced in ZnO. The permittivity of the composite is improved by both changes. The composite containing 15 wt% ZnO particles and 3 wt% MWCNTs exhibits a wider effective absorption bandwidth and lower minimum reflection coefficient than both SiO2 reinforced with 15 wt% ZnO particles and SiO2 reinforced with 3 wt% MWCNTs.  相似文献   

10.
《Ceramics International》2017,43(2):1677-1681
A novel green emitting long afterglow phosphor Li2Ca0.4Sr0.6SiO4:Tb3+ was obtained via a high temperature solid-state reaction in air atmosphere. X-ray diffraction (XRD), photoluminescence spectroscope (PLS), long afterglow spectroscope (LAS) and thermal luminescence spectroscope (TLS) were performed to characterize the physical properties of the phosphors. Typical 5D4-7Fj transitions of Tb3+ ions were detected by PL spectra, corresponding to CIE chromaticity coordinates of x =0.3456, y =0.5745. An optimal concentration of Tb3+ in the substrate was determined as 0.8 at%. The Li2Ca0.4Sr0.6SiO4 phosphors showed a typical afterglow behavior when the UV source was switched off. A typical triple exponential decay behavior was confirmed after fitting the experimental data. Thermal simulated luminescence study further indicated that the afterglow behavior of Li2Ca0.4Sr0.6SiO4:Tb3+ phosphors was generated by the recombination of electrons with the holes resulted from the doping of rare-earth ions (Tb3+) in Li2Ca0.4Sr0.6SiO4 host. The long afterglow luminescence mechanism of Li2Ca0.4Sr0.6SiO4:Tb3+ is illustrated and discussed in detail on the basis of experimental results.  相似文献   

11.
《Ceramics International》2016,42(11):13011-13017
H3BO3 was added during the preparation of Sr2MgAl22O36:Mn4+ phosphors by a high-temperature solid-state reaction method. The influence of H3BO3 flux on the crystal structure, particle morphology and photoluminescence properties of the Sr2MgAl22O36:Mn4+ phosphors was investigated by employing X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence spectroscopy, respectively. The results indicate that adding H3BO3 flux can improve the luminescence intensity and morphology, and reduce the synthesis temperature of the Sr2MgAl22O36 phosphor. The formation temperature of pure-phase Sr2MgAl22O36 was significantly decreased when H3BO3 flux as introduced. The excited state lifetime of the Sr2MgAl22O36:1.2 mol% Mn4+ phosphor by the addition of 2.0 wt% H3BO3 was ~1.02 ms. We demonstrated the potential of these phosphors to enhance sunlight harvesting by agricultural light conversion film testing. We propose that films containing the Sr2MgAl22O36:1.2 mol% Mn4+ phosphor can be applied to increase the production of agricultural plants.  相似文献   

12.
《Ceramics International》2016,42(6):6846-6849
Eu2+-activated LiSr3SiO4Cl3 phosphors were successfully designed, and prepared at low calcination temperature (650 °C). The crystal structure, morphology, and photoluminescence properties have been investigated in detail. The LiSr3SiO4Cl3 crystallizes in orthorhombic LiEu3SiO4Cl3-type structure. Under 316 nm excitation, the phosphor exhibits an asymmetric emission band peaking at 495 nm, which is probably attributed to the 4f–5d transitions of Eu2+ in various crystallographic sites. Their luminescence properties are investigated as a function of activator concentration (Eu2+). The quenching concentration of Eu2+ in LiEu3SiO4Cl3 is about 0.01 due to dipole–dipole interaction. The investigation indicates that Eu2+-activated LiEu3SiO4Cl3 phosphor can be used as a green emitting phosphor for white LEDs.  相似文献   

13.
《Ceramics International》2017,43(18):16622-16627
Trivalent dysprosium (Dy3+) ions -doped calcium silicate (Ca2SiO4) phosphors have been synthesized by utilizing agricultural waste of egg shell and rice husk through solid-state reaction method. The synthesized Ca2SiO4 powders thus obtained are crystallized in monoclinic structure with unit cell parameters of a = 5.53 Å; b = 6.67 Å; c = 9.13 Å; β = 87.43° and irregular shape morphology. Luminescent properties of Dy3+:Ca2SiO4 phosphors were studied by varying active ion concentration. The phosphors emit characteristic blue and yellow emissions of Dy3+ ions corresponding to the 4F9/26H15/2 and 4F9/26H13/2 transitions, respectively. Color coordinates evaluated from emission spectra are found to fall in the white light region. Decay curves for the 4F9/2 level of Dy3+ ions exhibit single exponential nature and turn into non-exponential with shortening of lifetime from 739 µs to 510 µs when Dy3+ ion concentration is increased from 0.001 to 0.5 mol%. All these results confirm that Ca2SiO4:Dy3+ phosphors are suitable for the use as low cost white light emitting phosphors.  相似文献   

14.
《Ceramics International》2017,43(15):11686-11691
A novel single-phase white-emitting phosphor La10(SiO4)6O3 (LSO): xEu has been synthesized by high-temperature solid-state reaction. Its crystal structure, luminescence properties, fluorescence decay time and oxygen vacancies have been characterized by X-ray diffraction (XRD) and photoluminescence (PL) spectra. XRD result shows a typical oxyapatite structure with the space group of P63/m. Characteristic excitation and emission peaks of Eu2+ and Eu3+ were observed from PL studies. The optimum doping concentration of Eu was found to be 7.5 mol% (x = 0.075). In this work, the lifetimes of Eu3+ and Eu2+ were considerably longer than those from some references. Under the excitation of different near ultraviolet (n-UV) longer wavelengths (λex = 360, 370, and 380 nm), the white light emission can be realized with the CIE chromaticity coordinates (0.3907, 0.3595), (0.3472, 0.3282), and (0.3504, 0.3062) for the phosphor LSO: 0.075Eu. The chromaticity coordinates of the phosphor were all located in the white region. Therefore, it is suggested that the explored LSO: 0.075Eu phosphor can be a good candidate for white light-emitting diodes (W-LEDs) application.  相似文献   

15.
《Ceramics International》2017,43(7):5674-5679
Non-rare-earth, red-emitting CaAl12O19:Mn4+ nanofiber phosphors have been successfully prepared by an electrospinning technique followed by an annealing process. The as-prepared precursor fibers have smooth surfaces with an average diameter of 5 µm. After annealing at high temperature, the diameter of the fibers gradually reduces due to the decomposition of the organic polymers. The photoluminescence and crystalline properties of the fibers were investigated as a function of Mn4+ concentration and the annealing temperature. Under ultraviolet and blue light excitation, CaAl12O19:Mn4+ exhibits a characteristic red emission at 655 nm with three satellite peaks due to the 2E→4A2 transition of Mn4+. The highest PL intensity is achieved at a 0.5% Mn4+ concentration and a firing temperature of 1400 °C. In comparison to CaAl12O19:Mn4+ prepared by a usual solid-state reaction, the luminescence of the as-prepared nanofiber phosphors in the present work has been strongly enhanced by optimizing the morphology and improving the crystallinity and phase purity. The absorption band in the blue region and a bright emission in the red region make the CaAl12O19:Mn4+ nanofiber phosphor a candidate for achieving high color rendering in YAG:Ce-based WLEDs. A warm WLED with a high CRI of 88.5 at a CCT of 4553 K has been successfully achieved by coating YAG:Ce with CaAl12O19:Mn4+ nanofiber phosphors on blue InGaN chips.  相似文献   

16.
《Ceramics International》2016,42(15):16579-16583
Tb3+-Sm3+ co-doped Sr9Gd(PO4)5(SiO4)F2 (SGPSF) phosphors were prepared through a solid-state reaction, and their luminescence properties as well as energy transfer mechanism have been investigated in detail. The SGPSF:Tb3+, Sm3+ phosphors system could be efficiently excited at wavelengths ranging from 200 to 500 nm, which is well matched with the spectra of near ultraviolet chips. The emission of SGPSF:Tb3+, Sm3+ phosphor covers the entire visible region with sharp peaks in the blue, green, and red regions. The emission color of SGPSF:Tb3+, Sm3+ could be adjusted from green (0.275, 0.378) to red (0.519, 0.295) by controlling the doping content of Sm3+/Tb3+.  相似文献   

17.
《Ceramics International》2017,43(9):6949-6954
Mn4+ doped and Mn4+/Cr3+ co-doped alkali metal titanate phosphors have been prepared by solid state reaction method. A part of Li+ ions in the Li2MgTiO4: Mn4+ are substituted with Na+ and K+ ions and consequently the intensity of Mn4+ emission at 678 nm is enhanced by 1.7 and 2.5 times, respectively. In the Mn4+/Cr3+ co-doped (Li0.95K0.05)2MgTi0.999O4, both emission of Cr3+at 726 nm and emission of Mn4+ at 678 nm of Mn4+ are observed. It is interesting to find that the intensity ratio of 726–678 nm emissions in the Mn4+/Cr3+ phosphor continually increases with excitation wavelength increasing from 290 nm to 455 nm, which means that the intensity ratio in turn can be used to identify the excitation light wavelength. This refers a possible approach to design novel compact light-wavelength detector or spectrometer based on the phosphor. The mechanism of Na+ or K+ substitution induced luminescence enhancement in the Mn4+ phosphor and the competition between the Cr3+ and Mn4+ emissions in the Mn4+/Cr3+ co-doped has been discussed.  相似文献   

18.
《Ceramics International》2016,42(15):16626-16632
A series of Ce3+ doped and Ce3+/Mn2+ co-doped calcium zirconium silicate CaZrSi2O7 (CZS) phosphors have been synthesized via conventional high temperature solid state reactions. The luminescence properties, energy transfer between Ce3+ and Mn2+ have been investigated systematically. Under 320 nm excitation, the phosphor CZS: 0.05Ce3+ exhibit strong blue emission ranging from 330 nm to 500 nm, attributed to the spin-allowed 5d-4f transitions of Ce3+ ions. There are two different emission centers of Ce3+ ions, Ce3+(I) and Ce3+(II). The emission spectra of Ce3+, Mn2+ co-doped phosphors shows a broad emission around 550 nm corresponding to the 4T1(4G)-6A1(6S) spin-forbidden transition of Mn2+. The energy transfer between Ce3+ and Mn2+ is detected and the transfer efficiency of Ce3+(II) to Mn2+ is faster than that of Ce3+(I) to Mn2+. The resonant type is identified via dipole-dipole mechanism. Additionally, a blue-shift emission of Ce3+ and a red-shift emission of Mn2+ have been observed following the increase of Mn2+ content in relation to the energy transfer. Thermal quenching has been investigated and the emission spectra show a blue-shift with the temperature increases, which have been discussed in details. CZS: 0.05Ce3+, yMn2+ phosphors can be tuned from blue to white and even to yellow by adjusting the Mn2+ content. All the results indicate that CZS: Ce3+, Mn2+ phosphor have a potential application for near-UV LEDs.  相似文献   

19.
《Ceramics International》2017,43(12):8824-8830
A series of Eu2+ and Mn2+ co-doping Sr3GdLi(PO4)3F phosphors have been synthesized through high temperature solid state reaction. Eu2+ single doped Sr3GdLi(PO4)3F phosphors have an efficient excitation in the range of 230–430 nm, which is in good agreement with the commercial near-ultraviolet (n-UV) LED chips, and gives intense blue emission centering at 445 nm. The critical distance of the Eu2+ ions in Sr3GdLi(PO4)3F is computed and demonstrated that the concentration quenching mechanism of Eu2+ is mostly caused by the dipole-dipole interaction. By co-doping Eu2+ and Mn2+ ions in the Sr3GdLi(PO4)3F host, the energy transfer from Eu2+ to Mn2+ that can be discovered. With the increase of Mn2+ content, emission color can be adjusted from blue to white under excitation of 380 nm, corresponding to chromatic coordinates change from (0.189, 0.108) to (0.319, 0.277). The energy transfer from Eu2+ to Mn2+ ions is proven to be a dipole-dipole mechanism on the basis of the experimental results and analysis of photoluminescence spectra and decay curves. This study infers that the obtained Sr3GdLi(PO4)3F:Eu2+, Mn2+ phosphors may be a potential candidate for n-UV LEDs.  相似文献   

20.
《Ceramics International》2016,42(9):11099-11103
Tb3+ions activated Ba4La6O(SiO4)6 (BLSO:Tb3+) phosphors were synthesized by a citrate sol-gel method. The X-ray diffraction pattern confirmed their oxyapatite structure. The field-emission scanning electron microscope image established that the BLSO:Tb3+phosphor particles were closely-packed and acquired irregular shapes. The photoluminescence (PL) excitation spectra of BLSO:Tb3+phosphors showed intense f–d transitions along with low intense peaks corresponding to the f–f transitions of Tb3+ions in the lower energy region. The PL emission spectra displayed the characteristic emission bands of Tb3+ions, and the optimized concentrations were found to be at 1 and 6 mol% for blue and green emission peaks, respectively. The cathodoluminescece (CL) spectra exhibited a similar behavior that was observed in the PL spectra except the intensity variations in the blue and green regions. The CL spectra of the BLSO:6 mol% Tb3+phosphor unveiled accelerating voltage induced luminescent properties.  相似文献   

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