共查询到20条相似文献,搜索用时 156 毫秒
1.
S. Sailaja S. J. Dhoble Nameeta Brahme B. Sudhakar Reddy 《Journal of Materials Science》2012,47(5):2359-2364
Novel green nanophosphors Ca2Gd2W3O14: Tb3+ were synthesized by solid state reaction method. From the X-ray diffraction profiles it is observed that Tb3+: Ca2Gd2W3O14 phosphors were crystallized in the form of tetragonal structure. The scanning electron microscopy (SEM) image shows that
the particle size is at around 300 nm. In addition to these the prepared powder phosphors were also examined by the energy
dispersive X-ray analysis (EDAX), Fourier transform infrared spectroscopy (FTIR), photoluminescence (PL) and mechanoluminescence
(ML) spectra. Emission spectra of Tb3+: Ca2Gd2W3O14 nanophosphors have shown bright green emission at 545 nm (5D4 → 7F5) with an excitation wavelength λexci = 374 nm (7F6 → 5G6). ML spectra shows the radiation effect on the Ca2Gd2W3O14: Tb3+ nanophosphors and from that it was observed that these phosphors are very less sensitive for lower exposure. 相似文献
2.
S. Sailaja S. J. Dhoble Nameeta Brahme B. Sudhakar Reddy 《Journal of Materials Science》2011,46(24):7793-7798
A new series of Eu3+ ions-activated calcium gadolinium tungstate [Ca2Gd2W3O14] phosphors were synthesized by conventional solid-state reaction method. The X-ray diffraction patterns of the powder samples
indicate that the Eu3+: Ca2Gd2W3O14 phosphors are of tetragonal structure. The prepared phosphors were well characterized by scanning electron microscopy (SEM),
energy dispersive X-ray analysis (EDAX), Fourier transform infrared spectroscopy (FTIR), photoluminescence (PL), and mechanoluminescence
(ML) spectra. PL spectra of Eu3+: Ca2Gd2W3O14 powder phosphors have shown strong red emission at 615 nm (5D0 → 7F2) with an excitation wavelength λ
exci = 392 nm (7F0 → 5L6). The energy transfer from tungstate groups to europium ions has also reported. Mechanoluminescence studies of Eu3+: Ca2Gd2W3O14 phosphors have also been explained systematically. 相似文献
3.
A series of Pr3+, Gd3+ and Pr3+–Gd3+-doped inorganic borate phosphors LiSr4(BO3)3 were successfully synthesized by a modified solid-state diffusion method. The crystal structures and the phase purities of samples were characterized by powder X-ray diffraction. Surface morphology of the sample was studied by scanning electronic microscopy (SEM). The optimal concentrations of dopant Gd3+ ions in compound LiSr4(BO3)3 were determined through the measurements of photoluminescence (PL) spectra of phosphors. Gd3+-doped phosphors LiSr4(BO3)3 show strong band absorption in UV spectral region and narrow-band UVB emission under the excitation of 276 nm was only due to 6P J → 8S7/2 transition of Gd3+ ions. The effect of Pr3+ ion on excitation of LiSr4(BO3)3:Gd3+ was also studied. The excitation of LiSr4(BO3)3:Gd3+, Pr3+ gives a broad-band spectra, which show very good overlap with the Hg 253.7 nm line. The photoluminescence spectra of LiSr4(BO3)3 with different doping concentrations Pr3+ and keeping the concentration of Gd3+ constant at 0.03 mol have also been studied. The emission intensity of LiSr4(BO3)3:Pr3+–Gd3+ phosphors increases with increasing Pr3+ doping concentration and reaches a maximum at 0.01 mol. From the photoluminescence study of LiSr4(BO3)3:Gd3+, Pr3+ we conclude that there was efficient energy transfer from Pr3+→ Gd3+ ions in LiSr4?x?y Pr x Gd y (BO3)3 phosphors. 相似文献
4.
Zhouyun Ren Chunyan Tao Hua Yang 《Journal of Materials Science: Materials in Electronics》2008,19(4):319-321
YAl3(BO3)4:Tb3+ phosphors were fabricated by the sol–gel method. The phosphor showed prominent luminescence in green due to the magnetic
dipole transition of 5D4–7F5. Structural characterization of the luminescent material was carried out with X-ray powder diffraction (XRD) analysis. Luminescence
properties were analyzed by measuring the excitation and photoluminescence spectra. Photoluminescence measurements indicated
that the phosphor exhibited bright green emission at about 541 nm under UV excitation. It is shown that the 11% of doping
concentration of Tb3+ ions in YAl3(BO3)4:Tb3+ phosphors is optimum. 相似文献
5.
Ba0.8Sr0.2TiO3 (BST) thick films co-doped with Yb3+ and Ho3+ were fabricated by the screen printing techniques on alumina substrates. The structure and morphology of the BST thick films
were studied by XRD and SEM, respectively. After sintered at 1240 °C for 100 min the BST thick films are polycrystalline with
a perovskite structure. The upconversion luminescence properties of the RE-doped BST thick films under 800 nm excitation at
room temperature were investigated. The upconversion emission bands centered at 470 and 534 nm corresponding to 5F1 → 5I8 and 5F4 → 5I8 transition, respectively were observed, and the upconversion mechanisms were discussed. The dependence of the upconversion
emission intensity upon the Ho3+ ions concentration was also examined; the emission intensity reaches a maximum value in the sample with 2 mol% Yb3+ and 0.250 mol% Ho3+ ions. All the results show that the BST thick films co-doped with Yb3+ and Ho3+ may have potential use for photoelectric devices. 相似文献
6.
Xiao-Yu Sun Zheng He Xuan Gu 《Journal of Materials Science: Materials in Electronics》2018,29(20):17217-17221
Zn2GeO4, Zn2GeO4:Mn2+, Zn2GeO4:Pr3+ and Zn2GeO4:Mn2+/Pr3+ phosphors were fabricated by a solid state reaction. The phase and luminescent properties of the fabricated phosphors were investigated. The XRD patterns show that all of the fabricated phosphors have an orthorhombic structure. The fabricated Zn2GeO4 shows an emission band in the range of 350–550 nm. The fabricated Zn2GeO4:Mn2+ and Zn2GeO4:Pr3+ phosphors show emission bands corresponding to Mn2+ and Pr3+ ions, respectively. The fabricated Zn2GeO4:Mn2+/Pr3+ phosphor shows the emission band results from Mn2+ and the codoped Pr3+ enhances the emission intensity of Mn2+. Moreover, Zn2GeO4:Mn2+/Pr3+ phosphor exhibits longer decay time than that of Zn2GeO4:Mn2+. The higher intensity and longer lifetime of Mn2+ emission are induced by the energy transfer from Pr3+ of various vacancies to Mn2+ in Zn2GeO4:Mn2+/Pr3+ phosphors. 相似文献
7.
The novel Ca4?x(PO4)2O: xDy3+ and Ca4?x?y(PO4)2O: xDy3+, yEu2+ multi-color phosphors were synthesized by traditional solid-state reaction. The crystal structure, particle morphology, photoluminescence properties and energy transfer process were investigated in detail. The X-ray diffraction (XRD) results demonstrate that the products showed pure monoclinic phase of Ca4(PO4)2O when x < 0.1. The scanning electron microscopy (SEM) indicated that the phosphors were grain-like morphologies with diameters of ~ 3.7–7.0 μm. Under excitation of 345 nm, Dy3+-doped Ca4(PO4)2O phosphors showed multi-color emission bands at 410, 481 and 580 nm originated from oxygen vacancies and Dy3+. Interestingly, Ca4(PO4)2O: Dy3+, Eu2+ phosphors exhibited blue emission band at 481 nm and broad emission band from 530 to 670 nm covering green to red regions. The energy transfer process from Dy3+ to Eu2+ was observed for the co-doped samples, and the energy transfer efficiency reached to 60% when Eu2+ molar concentration was 8%. In particular, warm/cool/day white light with adjustable CCT (2800–6700 K) and high CRI (Ra > 85) can be obtained by changing the Eu2+ co-doping contents in Ca4(PO4)2O: Dy3+, Eu2+ phosphors. The optimized Ca3.952(PO4)2O: 0.04Dy3+, 0.008Eu2+ phosphor can achieve the typical white light with CCT of 4735 K and CRI of 87. 相似文献
8.
Ling-Zhi Li Bing Yan Li-Xia Lin Yan Zhao 《Journal of Materials Science: Materials in Electronics》2011,22(8):1040-1045
The Eu3+ and Tb3+ ions activated SrWO4 phosphors have been synthesized by solid state method. The crystal structures and morphologies of the products are characterized
by Powders X-ray Diffraction (XRD) and scanning electronic microscopy (SEM). The results indicated that both SrWO4:Eu3+ and SrWO4:Tb3+ phosphors belong to tetragonal phase, and the particles of the phosphors become aggregate with the increase of calcinations
temperature. Analyzed by luminescent spectra, the dominant emission of Eu3+ in SrWO4, which is the typical hypersensitive transition 5D0 → 7F2 (613 nm), and the green emission (5D4 → 7F5) intensity of Tb3+ in SrWO4:Tb3+ is also dominant. The reaction temperature had obvious influence on the luminescent properties. The intensity reached the
strongest when it is sintered at 900 °C. Therefore, we can try to select the right temperature in order to obtain the ideal
product. 相似文献
9.
Nenghuo Wang Weiren Zhao Junhua Chen Jianqing Wang Yingjun Meng Shuangping Yi Yanjuan Zhu 《Journal of Materials Science: Materials in Electronics》2016,27(7):6681-6689
A series of polycrystalline Na4Ca4(Si6O18):Eu3+ orange emitting phosphors were synthesized by a conventional high-temperature solid-state reaction. The phase formation was confirmed by X-ray power diffraction analysis. The excitation spectra show a strong host absorption indicating an efficient energy transfer process from O2? to Eu3+ ions. Upon NUV radiation, the phosphors showed strong red emission around 610 nm (5D0 → 7F2) and orange emission around 591 nm (5D0 → 7F1), but the 5D1,2,3 emission nearly can not be seen. Compared with the luminescence properties of Li+, Na+, and K+ co-doped samples, we deduced that Na+ ions probably prefer to dope into the intrinsic Na vacancies rather than Ca2+ ions vacancies in Na4Ca4(Si6O18) crystal. Thermal stability properties, quantum efficiency and chromaticity coordinates of the phosphors have been investigated for the potential application in white LEDs. 相似文献
10.
T. K. Visweswara Rao Ch. Satya Kamal T. Samuel Valluru Srinivasa Rao Vanukuru Srinivasa Rao P. V. S. S. S. N. Reddy K. Ramachandra Rao 《Journal of Materials Science: Materials in Electronics》2018,29(2):1011-1017
Bi3+-activated LaAlO3:Ho3+ Phosphor, was prepared by Polyol method, and its photoluminescent properties were investigated under (UV) light excitation. Luminescence studies indicated that optimum concentration of Bi3+ and Ho3+ in LaAlO3 was found to be 1 and 1.5 at.%. The luminescent intensity of Ho3+ emission lines was remarkably enhanced on exciting with 272 nm, which suggested that efficient energy transfer from Bi3+ ions to Ho3+ ions takes place. There is significant energy overlap between the emission band of Bi3+ ions and the excitation band of Ho3+ ions.The ET efficiency has been calculated and found to be 69%. The critical ET distance has been calculated by the concentration–quenching method. The enhanced intensity and tuned luminous color of LaAlO3: Bi3+/Ho3+ phosphors from blue to cyan provides a promising material for field emission display devices. 相似文献
11.
Linhui Gao Yue An Hongliang Zhu Lun Wang Jianjun Chen Naiyan Wang Guofu Ou 《Journal of Materials Science》2011,46(5):1337-1340
This article presents the synthesis and photoluminescence (PL) properties of Y2Zr2O7:Tb3+. The Tb3+-doped Y2Zr2O7 zirconates were successfully synthesized by a hydrothermal process at 200 °C for 20 h. X-ray diffractometer (XRD) patterns
revealed that all of the products were phase-pure with the fluorite structure. PL study showed that the Y2Zr2O7:Tb3+ phosphors exhibited obvious PL emission peaks which located at 490, 545, 585, and 623 nm; the dominant emission located at
545 nm is assigned to 5D4 → 7F5 transition. Furthermore, Tb3+-doping concentration strongly affected the PL properties, and the quenching concentration is 5 at.%. 相似文献
12.
Xiao Chun Zhou Lu Ping Zhong Qiu Ping Liu Ren Yun Kuang Hong Mei Chen 《Inorganic Materials》2009,45(11):1295-1298
New red emitting phosphors, Ca3(VO4)2:Eu3+,Bi3+, Ca3((P,V)O4)2:Eu3+ were synthesized by low temperature solid-state reaction and characterized by X-ray diffraction, scanning electron microscopy, photoluminescence spectra and Fourier transform infrared spectroscopy. The results show that the red emission located at about 613 nm was ascribed to 5 D 0-7 F 2 transition of Eu3+. The effect of by Bi doping and by P doping was also investigated systematically. 相似文献
13.
Jinsheng Liao Bao Qiu He-Rui Wen Yong Li Ruijin Hong Hangying You 《Journal of Materials Science》2011,46(5):1184-1189
Monodispersed spheres (1–4 μm in diameter) of BaWO4:Eu3+ (hereafter BWO:Eu) red-phosphor exhibiting intense emission at 615 nm were synthesized via a mild hydrothermal method. X-ray
diffraction, scanning electron microscope, photoluminescence excitation and emission spectra, and decay curve were used to
characterize the properties of BWO:Eu phosphors. An intense red emission was obtained by exciting either into the 5L6 state with 394 nm or the 5D2 state with 465 nm, that correspond to two popular emission lines from near-UV and blue LED chips, respectively. The values
of Ω
2,4 experimental intensity parameters (13.8 × 10−20 and 8.2 × 10−20 cm2) are determined. The high-emission quantum efficiency of the BWO:Eu phosphor suggests this material could be promising red
phosphors for generating white light in phosphor-converted white light-emitting diodes. 相似文献
14.
Y. Y. Zhang J. L. Liu Y. X. Zhu Y. Shang M. Yu X. Huang 《Journal of Materials Science》2009,44(13):3364-3369
Nanocrystalline SrCO3:Tb3+ phosphor layers were coated on monodisperse and spherical polystyrene particles by a typical hydrothermal synthesis without
further annealing treatment, resulting in the formation of core-shell-structured polystyrene@SrCO3:Tb3+ particles. X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, photoluminescence,
as well as lifetimes were employed to characterize the resulting composite particles. Under ultraviolet excitation, the polystyrene@SrCO3:Tb3+ phosphors show the characteristic 5D4–7F
J
(J = 6, 5, 4, 3) emission lines with green emission 5D4–7F5 (544 nm) as the most prominent group. The obtained core-shell phosphors are potentially applied in fluorescent lamps. 相似文献
15.
Yanxia Tang Yongfei Ye Haihui Liu Xiongfei Guo Hongxia Tang Wenzhong Yin Yaping Gao 《Journal of Materials Science: Materials in Electronics》2017,28(2):1301-1306
NaLa(WO4)2:Eu3+ phosphors with different Eu3+ concentrations have been synthesized by a hydrothermal method. The phase is confirmed by XRD analysis, which shows a pure-phase NaLa(WO4)2 XRD pattern for all of NaLa(WO4)2:Eu3+ phosphors. The SEM and TEM images indicate that all of NaLa(WO4)2:Eu3+ phosphors have a octahedral morphology. These suggest that the Eu3+ doping has no influence on the structure and growth of NaLa(WO4)4 particles. By monitoring the emission of Eu3+ at 615 nm, NaLa(WO4)2:Eu3+ phosphors show excitation bands originating from both host and Eu3+ ions. Under the excitation at 271 nm corresponding to WO4 2? groups, emission bands coming from the 1A1 → 3T1 transition with the WO4 2? groups and the 5D0 → 7Fj (j = 0, 1, 2, 3 and 4) transitions of Eu3+ are observed. The emission intensity relating to WO4 2? groups decreases with increasing Eu3+ concentration. But emission intensities of Eu3+ increase firstly and then decreases because of concentration quenching effect. Under the excitation at 395 nm corresponding to 7F0 → 5L6 transition of Eu3+, only characteristic Eu3+ emission bands can be observed. The results of this work suggest that tunable luminescence can be obtained for Eu3+ doped NaLa(WO4)2 phosphors by changing Eu3+ concentration and excitation wavelength. 相似文献
16.
O. Ya. Manashirov A. N. Georgobiani V. B. Gutan E. M. Zvereva A. N. Lobanov 《Inorganic Materials》2011,47(9):1006-1011
We have identified general relationships between the spectral and kinetic properties of the IR Stokes luminescence bands of
Y1 − x − y
Nd
x
Pr
y
PO4 solid solutions in the spectral range 0.86–1.40 μm under 0.810-μm laser excitation. The results have been used to formulate
technical requirements for the purity of rare-earth oxides for the fabrication of efficient YPO4:Nd3+ IR phosphors and to develop a fast YPO4:Nd3+, Pr3+ IR phosphor that allows the decay time of the Nd3+ IR Stokes luminescence bands in the range 0.86–1.40 μm to be tuned from 50 to 170 μs by varying the ratio of the Nd3+ and Pr3+ concentrations. 相似文献
17.
Bowen Zhang Mingming Shi Dongyun Zhang Yunyun Guo Chengkang Chang WeiJie Song 《Journal of Materials Science: Materials in Electronics》2017,28(16):11624-11630
This paper reports the comparison of photoluminescence and afterglow behavior of Dy3+ in CaSnO3 and Ca2SnO4 phosphors. The samples containing CaSnO3 and Ca2SnO4 were prepared via solid-state reaction. The properties have been characterized and analyzed by utilizing X-ray diffraction (XRD), photoluminescence spectroscope (PLS), X-ray photoelectron spectroscopy (XPS), afterglow spectroscopy (AS) and thermal luminescence spectroscope (TLS). The emission spectra revealed that CaSnO3:Dy3+ and Ca2SnO4:Dy3+ phosphors showed different photoluminescence. The Ca2SnO4:Dy3+ phosphor showed a typical 4F9/2 to 6Hj energy transition of Dy3+ ions, with three significant emissions centering around 482, 572 and 670 nm. However, the CaSnO3:Dy3+ phosphor revealed a broad T1 → S0 transitions of Sn2+ ions. The XPS demonstrate the existence of Sn2+ ions in CaSnO3 phosphor caused by the doping of Dy3+ ions. Both the CaSnO3:Dy3+ and Ca2SnO4:Dy3+ phosphors showed a typical triple-exponential afterglow when the UV source switched off. Thermal simulated luminescence study indicated that the persistent afterglow of CaSnO3:Dy3+ and Ca2SnO4:Dy3+ phosphors was generated by the suitable electron or hole traps which were resulted from the doping the calcium stannate host with rare-earth ions (Dy3+). 相似文献
18.
I. V. Berezovskaya N. P. Efryushina A. S. Voloshinovskii S. I. Vdovenko I. P. Kovalevskaya V. P. Dotsenko 《Inorganic Materials》2012,48(5):539-543
We have studied the luminescent properties of Eu2+ and Eu3+ in the calcium chloride borate Ca2BO3Cl under optical and synchrotron excitation. The results demonstrate that a reductant should be present during synthesis in
order to stabilize Eu2+ in Ca2BO3Cl and provide insight into the factors responsible for the long-wavelength position of the luminescence band (λmax = 577 nm) and the relatively low Eu2+ stability in Ca2BO3Cl. 相似文献
19.
The spectral parameters of Nd3+ ions in Nd:LaCa4O(BO3)3 crystal have been investigated based on Judd-Ofelt theory. The spectral parameters were obtained: the intensity parameters
Ωλ are Ω2 =1.98 × 10–20 cm2, Ω4 =2.39 × 10–20 cm2, Ω6 =1.38 × 10–20 cm2, the radioactive lifetime is 655 μs, the quantum efficiency is 10%, and the fluorescence branch ratios were calculated: β1 = 0.51, β2 = 0.42, β3 = 0.066, β4 = 0.003.
Electronic Publication 相似文献
20.
Eu3+ activated CaSiO3, (Ca, Ba) SiO3 and (Ca, Sr) SiO3 have been prepared by sol-gel technique. Residual solvent and organic contents in the gel were removed by firing at 100°C
for 3–4 h at 300 and 600°C for 2 h. Small exothermic shoulder around 850 to 875°C, as observed in DTA curve, corresponds to
crystallization temperature of the doped calcium silicate. Influence of firing temperature on the luminescence of Eu3+ shows the maximum emission intensity in gel fired at 850°C. Photoluminescence emission peak is observed at 614 nm due to5D0 →7F2 transition of Eu3+ ion in (Ca, Ba) SiO3 and (Ca, Sr) SiO3 phosphors, when excited by 254 nm. The (Ca, Ba) SiO3 material is proposed as an efficient red phosphor. 相似文献