共查询到20条相似文献,搜索用时 15 毫秒
1.
The structure and photoluminescence (PL) properties of Sr3SiO5 : Sm3+ and Li+-doped Sr3SiO5 : Sm3+ red-emitting phosphors were investigated. Samples were prepared by the high-temperature solid-state method. PL spectra show that the concentration quenching occurs when the Sm3+ concentration is beyond 1.3 mol% in Sr3SiO5 : Sm3+ phosphor without doping Li+ ions. The concentration-quenching mechanism can be explained by the electric dipole-dipole interaction of Sm3+ ions. The incorporation of Li+ ions into Sr3SiO5 : Sm3+ phosphors, as a charge compensator, improves the PL properties. The lithium ions also suppress the concentration quenching in Sm3+ with concentration increased from 1.3 mol% to 1.7 mol%. 相似文献
2.
The Y0.95?xAlxVO4:5%Eu3+ (0≤x≤0.1) phosphors were successfully synthesized by solid state reaction at 900 °C for 6 h, and their luminescence properties were investigated under UV and VUV excitation. Monitoring at 619 nm, a strong broad absorption was enhanced by co-doping of Al3+ into the YVO4:Eu3+ lattices at 256 nm under UV excitation. The VUV excitation spectra also showed the enhanced excitation bands at about 156 and 200 nm. Under 254 or 147 nm excitation, it was found that Y0.95?xAlxVO4:Eu3+(0≤x≤0.1) phosphors showed strong red emission at about 619 nm corresponding to the electric dipole 5D0–7F2 transition of Eu3+. The improvement of luminescence intensity of YVO4:Eu3+ was also observed after partial substituting Y3+ by Al3+ and the optimal luminescence intensity appeared with incorporation of 2.5 mol% Al3+. 相似文献
3.
N. Dhananjaya H. Nagabhushana B. M. Nagabhushana S. C. Sharma B. Rudraswamy N. Suriyamurthy C. Shivakumara R. P. S. Chakradhar 《Applied physics. B, Lasers and optics》2012,107(2):503-511
Gd2O3:Eu3+ (4 mol%) co-doped with Bi3+ (Bi = 0, 1, 3, 5, 7, 9 and 11 mol%) ions were synthesized by a low-temperature solution combustion method. The powders were calcined at 800°C and were characterized by powder X-ray diffraction (PXRD), transmission electron microscopy (TEM), Fourier transform infrared and UV–Vis spectroscopy. The PXRD profiles confirm that the calcined products were in monoclinic with little cubic phases. The particle sizes were estimated using Scherrer’s method and Williamson–Hall plots and are found to be in the ranges 40–60 nm and 30–80 nm, respectively. The results are in good agreement with TEM results. The photoluminescence spectra of the synthesized phosphors excited with 230 nm show emission peaks at ~590, 612 and 625 nm, which are due to the transitions 5D0→7F0, 5D0→7F2 and 5D0→7F3 of Eu3+, respectively. It is observed that a significant quenching of Eu3+ emission was observed under 230 nm excitation when Bi3+ was co-doped. On the other hand, upon 350 nm excitation, the luminescent intensity of Eu3+ ions was enhanced by incorporation of Bi3+ (5 mol%) ions. The introduction of Bi3+ ions broadened the excitation band of Eu3+ of which a new strong band occurred ranging from 320 to 380 nm. This has been attributed to the 6s2→6s6p transition of Bi3+ ions, implying a very efficient energy transfer from Bi3+ ions to Eu3+ ions. The gamma radiation response of Gd2O3:Eu3+ exhibited a dosimetrically useful glow peak at 380°C. Using thermoluminescence glow peaks, the trap parameters have been evaluated and discussed. The observed emission characteristics and energy transfer indicate that Gd2O3:Eu3+, Bi3+ phosphors have promising applications in solid-state lighting. 相似文献
4.
The alkaline phosphate based LiNa3P2O7:Tb3+ phosphors are prepared by solid state reaction method. X-ray diffraction (XRD) analysis shows that all the powders possess orthorhombic structure. Fourier transform infrared (FTIR) spectroscopy studies suggest that the phosphor belong to the diphosphate family. The morphology of the phosphors is identified by scanning electron microscopy (SEM). Upon 378 nm excitation, the LiNa3P2O7:Tb3+ phosphors shown emission bands at 482, 545, 588 and 620 nm corresponding to the transitions 5D4→7F6, 5D4→7F5, 5D4→7F4 and 5D4→7F3, respectively. The optimized concentration of Tb3+ in LiNa3P2O7 phosphor is found to be 9 mol%. The concentration quenching mechanism was proved to be the exchange interaction between two nearest Tb3+ ions with the critical distance (Rc) of 1.18 nm. The Commission International de l'Eclairage (CIE) coordinates evidence that the phosphors emit in the green light region. Thermoluminescence properties of the prepared phosphors are studied by pre-irradiating the powders with different doses of UV irradiation. The kinetic parameters of TL glow curves are calculated using Chen's peak shape method. 相似文献
5.
YxVO4:0.01Dy3+ and Y0.99-xVO4:0.01Dy3+,xBi3+ phosphors were synthesized by chemical coprecipitation method.Their crystal structure,micromorphology and photoluminescence (PL) properties were investigated by X-ray diffraction (XRD),scan electron microscopy (SEM) and spectrofluorometer.YxVO4:0.01Dy3+ and Y0.99-xVO4:0.01Dy3+,xBi3+ phosphors have a broad excitation band from about 250 to 350 nm including a strongest peak at about 310 nm.Under its excitation,the emission spectra exhibits two sharp peaks,one of which centered at about 483 nm for 4 F9/2→6 H15/2 transition of Dy3+ and the other at about 574nm due to the 4F9/2→6H13/2 transition of Dy3+.For YxVO4:0.01Dy3+ (x=0.94,0.97,0.99,1.01,1.03)phosphor,with increasing value of x,the body color of phosphor changes from yellow to white and the strongest peak in the excitation spectra shifts a little to shorter wavelength.It is detrimental to luminous intensity when Y3+ content deviates stoichiometric ratio.For Y0.99-xVO4:0.01Dy3+,xBi3+ (x=0.01,0.05,0.1,0.15,0.2,0.25) phosphor,the samples have extraneous bismuth vanadium oxide phase except for the major tetragonal zircon structure when x≥0.20.With increasing value of x,the band edge in the excitation spectra shifts to longer wavelength,the excitation intensity and luminous intensity increase early and decrease late.When the value of x is 0.01,the intensities increase evidently.In addition,the influence of Y3+ or Bi3+ on the color temperature of emission and micromorphology of YVO4:Dy3+ is slight. 相似文献
6.
7.
8.
《Radiation measurements》2000,32(4):349-353
Thorium oxide doped with trivalent terbium ions offers itself as a novel phosphor with its photo- and thermally-stimulated luminescence (PL and TSL) characteristics showing a marked change on sustained exposure to 254 and 365 nm ultraviolet (UV) radiation. The reduction in luminescence intensity of Tb3+ ions, on irradiation with 254 nm photons and subsequent restoration on exposure to 365 nm, has been correlated with the complimentary behaviour in UV-induced TSL. These changes are, in turn, ascribed to inter-configurational (f–d) transitions and e–h formation and recombination processes. UV radiation induced TSL output increases linearly with incident UV radiant energy at a constant radiation flux; however, for a fixed exposure, TSL output increases with increase in radiant flux. 相似文献
9.
Low-power-threshold cw laser-induced incandescence (CWLII) has been observed in La(2)O(3):Er(3+)-Yb(3+) phosphor on excitation by a 976 nm IR laser. It is suggested that incandescence originates from the extensive heating induced by the nonradiative processes taking place following the laser excitation. Other mechanisms for similar observations have also been suggested in the literature and have been discussed with the present observations. The estimated temperature for the CWLII approaches around 2650 K, and this seems to provide an effective way to rapidly attain high temperature in nano/microvolumes of phosphor. The phosphor exhibited efficient upconversion, and the ratio of the (2)H(11/2)→(4)I(15/2) and (4)S(3/2)→(4)I(15/2) band intensities of Er(3+) permits measurement of the temperature rise, from a distance. 相似文献
10.
Guoyi Dong Hengxin Ma Yufeng Liu Zhiping Yang Qingbo Liu 《Optics Communications》2012,285(20):4097-4101
A series of orange reddish emitting phosphors Eu3+-doped Sr3Bi(PO4)3 have been successfully synthesized by conventional solid-state reaction, and its photoluminescence (PL) properties have been investigated. The excitation spectra reveal strong excitation bands at 392 nm, which match well with the popular emissions from near-UV light-emitting diode chips. The emission spectra of Sr3Bi(PO4)3:Eu3+ phosphors invariably exhibit five peaks assigned to the 5D0→7FJ (J=0, 1, 2, 3, 4) transitions of Eu3+ and have dominating emission peak at 612 nm under 392 nm excitation. The luminescence intensity was enhanced with increasing Eu3+ content and the emission reached the maximum intensity at x=0.05 in Sr3Bi(PO4)3:xEu3+. The energy transfer behavior in the phosphors was discussed. The Commission Internationale de lEclairage (CIE) chromaticity coordinates, the quantum efficiencies, and the decay curves of the entitled phosphors excited under 392 nm are also investigated. The experimental results indicate that the Eu3+-doped Sr3Bi(PO4)3 phosphors are promising orange reddish-emitting phosphors pumped by near-UV light. 相似文献
11.
《Physics letters. A》1987,121(2):94-96
The details of the photoluminescence and excitation spectra are obtained at various temperatures between 6 and 300 K. At low temperatures, the emission band originating from the 3A1u(sp) → 1A1g(s2) transition in a Bi3+ ion shows vibrational structure. In the excitation spectra, the A- and C-bands are observed at 365 and about 250 nm, respectively. 相似文献
12.
Zhiguo Xia Daimei Chen Min Yang Ting Ying 《Journal of Physics and Chemistry of Solids》2010,71(3):175-180
YVO4:Eu3+,Bi3+ phosphors have been prepared by the high-temperature solid-state (HT) method and the Pechini-type sol-gel (SG) method. Spherical SiO2 particles have been further coated with YVO4:Eu3+,Bi3+ phosphor layers by the Pechini-type SG process, and it leads to the formation of core-shell structured SiO2/YVO4:Eu3+,Bi3+ phosphors. Therefore, the phase formations, structures, morphologies, and photoluminescence properties of the three types of as-prepared YVO4:Eu3+,Bi3+ phosphors were studied in detail. The average diameters for the phosphor particles are 2-4 μm for HT method, 0.1-0.4 μm for SG method, and 0.5 μm for core-shell structured SiO2/YVO4:Eu3+,Bi3+ particles, respectively. Photoluminescence spectra show that effective energy transfer takes place between Bi3+ and Eu3+ ions in each type of as-prepared YVO4:Eu3+,Bi3+ phosphors. Introduction of Bi3+ into YVO4:Eu3+ leads to the shift of excitation band to the long-wavelength region, thus the emission intensities of 5D0-7F2 electric dipole transition of Eu3+ at 615 nm upon 365 nm excitation increases sharply, which makes this phosphor a suitable red-emitting materials that can be pumped with near-UV light emitting diodes (LEDs). 相似文献
13.
利用高温固相反应法制备了Eu3+掺杂的Sr2CeO4样品,并对其吸附水前后的光谱特性进行了研究.结果发现,对于刚制备的Sr2-xEuxCeO4+x/2样品, 在Ce4+-O2-的电荷迁移激发中,只有强激发带(~35700cm-1)与Eu3+离子间存在能量传递,而弱激发带 (~29400cm-1)只是引起Ce4+-O2-的电荷迁移发射;在Sr2-xEuxCeO4+x/2样品吸附水后,Eu3+的线状吸收跃迁强度显著增加, Ce4+-O2-两个激发带均向Eu3+离子传递能量. Ce4+-O2-强激发带通过交换作用向Eu3+离子传递能量,而弱激发带与Eu3+离子间的能量传递机理是非辐射多极子近场力的相互作用. 相似文献
14.
以CaCO3(99.9%)、Li2CO3(99.9%)、Na2CO3(99.9%)K2CO3(99.9%)、H3BO3(99.9%)、Sm2O3(99.9%)为原料,按所设计的化学计量比称取以上原料,在玛瑙研钵中混合均匀并充分研磨,装入刚玉坩埚,采用固相法制备LiCaBO3:Sm3+材料;通过美国XRD6000型X射线衍射仪和日本岛津RF-540荧光分光光度计对材料的性能进行表征,所有测量均在室温条件下进行。LiCaBO3:Sm3+材料的发射光谱由三个橙红色发射峰组成,主峰位于561,602,651nm,分别对应Sm3+的4G5/2→6H5/2、4G5/2→6H7/2和4G5/2→6H9/2跃迁;监测602nm发射峰,得到其激发光谱由320~420nm的宽激发带组成。由激发和发射光谱看出,LiCaBO3:Sm3+能够有效地被紫外LED芯片激发,发射红色光。研究了Sm3+浓度(x)对LiCa1-xBO3:xSm3+材料发射强度的影响,结果表明:随Sm3+浓度的增大,发射强度先增强后减弱,Sm3+掺杂摩尔分数为3%时,发射强度最大,依据Dexter理论,计算得出其浓度猝灭机理为电偶极-偶极相互作用。掺入电荷补偿剂Li+、Na+和K+均提高了LiCaBO3:Sm3+材料的发射强度。 相似文献
15.
B.N. Mahalley S.J. Dhoble R.B. Pode G. Alexander 《Applied Physics A: Materials Science & Processing》2000,70(1):39-45
The doubly doped (Bi3+ and Eu3+) GdVO4 powder is synthesized by hydrolyzed colloid reaction (HCR) technique and formation of material is confirmed by XRD measurement. Surface morphology has been studied by SEM measurement and the result shows uniform surface morphology. The average particle size observed by SEM is about 1 7m. The Fritsch particle sizer is used to study the particle size distribution. It distributes from O.15 to 3.57 7m. The small particle size (less than 5 7m) and the narrow particle size distribution, are the necessary requirements of good phosphor material. Photoluminescence result shows a narrow emission line of Eu3+ ion (4 nm FWHM) at 618 nm. The Eu3+ emission intensity is enhanced by a factor of five with the addition of small amount of Bi3+. The emission bands of VO43- and Bi3+ partially overlap with the excitation band of Eu3+. The process of energy transfer from Bi3+ to Eu3+ is discussed here. The energy transfer probability is strongly dependent upon the Bi3+ and Eu3+ concentrations, with a maximum for 0.2 mol % of Bi3+ and 3 mol % of Eu3+. It drastically decreases for higher concentrations. For photoluminescent applications, the quantum efficiency (QE) of a phosphor material is an important parameter. The QE of GdVO4:Bi,Eu(0.2,3) is 76%. The GdVO4:Bi,Eu(0.2,3) material is proposed as an efficient photoluminescent phosphor. 相似文献
16.
Yb3+ doped phosphor of Gd2O3 (Gd2O3:Yb3+) have been prepared by solid state reaction method. The structure and the particle size have been determined by X-ray powder diffraction measurements. The average particle size of the phosphor is in between 35 and 50 nm. The particle size and structure of the phosphor was further confirmed by TEM analysis. The visible and NIR luminescence spectra were recorded under the 980 nm laser excitation. The visible upconversion luminescence of Yb3+ ion was due to cooperative luminescence and the presence of rare earth impurity ions. The cooperative upconversion and NIR luminescence spectra as a function of Yb3+ ion concentration were measured and the emission intensity variation with Yb3+ ion concentration was discussed. Yb3+ energy migration quenched the cooperative luminescence of Gd2O3:Yb3+ phosphor with doping level over 5%, while the NIR emission luminescence continuously increases with increasing Yb3+ ion concentration. 相似文献
17.
The crystalline structure and photoluminescence (PL) properties of europium-doped cerium dioxide synthesized by the solid-state reaction method were analyzed. CeO2:Eu3+ phosphor powders exhibit the pure cubic fluorite phase up to 10 mol% doping concentration of Eu3+. With indirect excitation of CeO2 host at 373 nm, the PL intensity quickly increases with increasing Eu3+ concentration, up to about 1 mol%, and then decreases indicating the concentration quenching. While with direct excitation (467 nm), much more stronger PL emissions, especially the electric dipole emission 5D0-7F2 at 612 nm, are observed and no concentration quenching occurs up to 10 mol% doping concentration of Eu3+. The nature of this behavior and the cause of the concentration quenching were discussed. 相似文献
18.
Yb3+/Er3+ co-doped Gd6MoO12 and Yb3+/Er3+/Li+ tri-doped Gd6MoO12 phosphors were prepared by adjusting the annealing temperature via the high temperature solid-state method. Under the excitation of 980 nm semiconductor, the upconversion luminescence properties were investigated and discussed. In the experimental process, we get the optimum Yb3+ concentration and the concentration quench effect will happen while the concentration extends the given region. According to the Yb3+ concentration quenching effects, the critical distance between Yb3+ ions had been calculated. The measured UC luminescence exhibited a strong red emission near 660 nm and green emission at 530 nm and 550 nm, which are due to the transitions of Er3+(4F9/2, 2H11/2, 4S3/2) → Er3+(4I15/2). Then the effect of excitation power density in different regions on the upconversion mechanisms was investigated and the calculated results demonstrate that the green and red upconversion is a two-photon process. A possible mechanism was discussed. After Li+ ions mixing, the upconversion emission enhanced largely, and the optimum Li+ concentration was obtained while fixed the Yb3+ and Er3+ on the above optimum concentration. This enhancement owns to the decrease of the local symmetry around Er3+ after Li+ ions doping into the system. This result indicates that Li+ is a promising candidate for improving luminescence in some case. 相似文献
19.
Dy3+ and Sm3+ doped Sr5SiO4Cl6 phosphors were prepared by the modified solid state method and their luminescent properties were studied. From a powder X-ray diffraction (XRD) analysis the formation of Sr5SiO4Cl6 was confirmed. In the photoluminescence emission spectra, the Sr5SiO4Cl6:Dy3+ phosphors show efficient blue and yellow band emissions, which originates from the 4F9/2→6H15/2 and 4F9/2→6H13/2 transitions of Dy3+ ion, respectively. Photoluminescence properties of Sm3+ doped Sr5SiO4Cl6 phosphor exhibited characteristic orange-red emission coming from the intra-4f-shell 4G5/2 →6HJ electron transitions. 相似文献
20.
Investigation on the X-ray diffraction results of rare earth ions such as Eu3+ and Nd3+ doped BaSnF4 materials indicates that the doped materials show a similar pattern of BaSnF4 with the same tetragonal structure (P4/nmm). The transport properties of the materials have been investigated by impedance spectroscopy, and the results show that the conductivity values are closely related to both concentration and type of the dopant ion. All of these doped materials show an increase in conductivity over un-doped BaSnF4. The highest conductivity is observed in 3 mol% Nd3+ ion-doped BaSnF4 system (9.01?×?10?4 Scm?1), which is about one order higher in comparison to BaSnF4 conductivity (1.1?×?10?4 Scm?1). The room temperature emission spectrum of BaSnF4:Eu3+ and BaSnF4:Nd3+ shows the characteristic bands arising from 5D0?→?7F j (j?=?1, 2, 3, and 4) and 4F3/2 to 4I j (j?=?9/2 and 11/2) transitions of Eu3+ and Nd3+ ions, respectively. 相似文献