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1.
Thermoluminescence (TL) and photoluminescence studies have been carried out on CaSO4:Tb, CaSO4:Ce and CaSO4:Tb,Ce phosphors with the aim of studying energy transfer process in the CaSO4:Tb,Ce phosphor. CaSO4:Tb,Ce shows TL peaks at 150, 220, 320 and 400°C. Changes in Tb and Ce concentrations influence the relative heights of these glow peaks. Co-doping with 0.1 mol% of Ce in CaSO4:Tb enhances the sensitivity of 320oC TL peak by a factor of 15. Fluorescence results show that there is energy transfer from Ce to Tb ion. The defect centres formed in CaSO4:Tb,Ce phosphor are studied using electron spin resonance technique. The 320oC glow peak correlates with a centre (SO3−radical) with g-values: g||=2.0061 and g⊥=2.0026. 相似文献
2.
ZnAl2O4:Tb phosphor was prepared by combustion synthesis. ZnAl2O4:Tb exhibits three thermally stimulated luminescence (TSL) peaks around 150, 275 and 350 °C. ZnAl2O4:Tb exhibits optically stimulated luminescence (OSL) when stimulated with 470 nm light.Electron spin resonance (ESR) studies were carried out to identify defect centres responsible for TSL peaks observed in ZnAl2O4:Tb. Two defect centres are identified in irradiated ZnAl2O4:Tb phosphor and these centres are assigned to V and F+ centres. V centre appears to correlate with the 150 °C TSL peak, while F+ centre could not be associated with the observed TSL peaks. 相似文献
3.
A new luminescent material, Eu3+ activated Ca3Sr3(VO4)4, was investigated. This compound shows a strong red emission centered at 618 nm under near-UV light with two distinct absorption bands; charge transfer state of VO43− and f-f transitions of europium ions. As the europium concentration is increased, an additional red-emitting phosphor, EuVO4, which is known to be a prominent luminescent material in the near-UV region can be traced. The UV excited luminescent properties of this material may find application in the production of red phosphors for white light-emitting diodes. 相似文献
4.
Eu2+ activated Ca5(PO4)3Cl blue-emitting phosphors were prepared by the conventional solid state method using CaCl2 as the chlorine source and H3BO3 as flux. The structure and luminescent properties of phosphors depend on the concentrations of Eu2+, the amount of CaCl2 and the usage of the H3BO3 flux were investigated systematically. Eu2+ and Mn2+ Co-doped Ca5(PO4)3Cl with blue and orange double-band emissions were also researched based on the optimal composition and synthesis conditions. The energy transfer between Eu2+ and Mn2+ was found in the phosphor Ca5(PO4)3Cl:Eu2+, Mn2+, and the Co-doped phosphor can be efficiently excited by near-UV light, indicating that the phoshor is a potentional candidate for n-UV LED used phosphor. 相似文献
5.
Xinmin Zhang Boowon Park Jongsu Kim Jungjun Lee Jinchul Choi 《Journal of luminescence》2010,130(1):117-120
Orange-emissive Ce3+/Eu2+ co-doped Sr3Al2O5Cl2 phosphors were synthesized by a solid-state reaction. The large overlap between the emission spectrum of blue Sr3Al2O5Cl2:Ce3+ and the excitation spectrum of orange Sr3Al2O5Cl2:Eu2+, and the shortening trend in lifetime of Ce3+ donors with increasing Eu2+ concentration in Sr3Al2O5Cl2:Ce3+, Eu2+ provide the strong evidence of energy transfer from Ce3+ to Eu2+ ions. It supports that the orange emission intensity of the optimal co-doped phosphor is 1.5 times stronger than that of single Eu2+-doped one. The Sr3Al2O5Cl2:Ce3+, Eu2+ phosphor is a promising orange-emitting phosphor for warm-white-light-emitting diode because of its effective excitation in the near ultraviolet range. 相似文献
6.
I.M. Nagpure Shreyas S. PitaleE. Coetsee O.M. NtwaeaborwaJ.J. Terblans H.C. Swart 《Applied Surface Science》2011,257(23):10147-10155
Tb3+-doped Sr3(PO4)2 phosphor was prepared by a sol-gel combustion method. A trigonal structure having Sr and O atoms occupying two different lattice sites were obtained. Scanning Auger nanoprobe was used to analyze the morphology of the particles. Photoluminescence (PL) and cathodoluminescence (CL) properties of Sr3(PO4)2:Tb powder phosphors were evaluated and compared. In addition, the CL intensity degradation of Sr3(PO4)2:Tb was evaluated when the powders were irradiated with a beam of electrons in a vacuum chamber maintained at an O2 pressure of 1 × 10−6 Torr or a background pressure of 1 × 10−8 Torr O2. The surface chemical composition of the degraded powders, analyzed by X-ray photoelectron spectroscopy (XPS), suggests that new compounds (metal oxides) of strontium and phosphorous were formed on the surface. It is most likely that these compounds contributed to the CL intensity degradation of the Sr3(PO4)2:Tb phosphors. The CL properties and possible mechanism by which the new metal oxides were formed on the surface due to a prolonged electron beam irradiation are discussed. 相似文献
7.
Electron spin resonance (ESR) studies were carried out to identify the defect centres responsible for the thermoluminescence (TL) and optically stimulated luminescence (OSL) processes in BeO phosphor. Two defect centres were identified in irradiated BeO phosphor by ESR measurements, which were carried out at room temperature and these were assigned to an O− ion and Al2+ centre. The O− ion (hole centre) correlates with the main 190 °C TL peak. The Al2+ centre (electron centre), which acts as a recombination centre, also correlates to the 190 °C TL peak. A third centre, observed during thermal annealing studies, is assigned to an O− ion and is related to the high temperature TL at 317 °C. This centre also appears to be responsible for the observed OSL process in BeO phosphor. 相似文献
8.
Lithium Calcium borate (LiCaBO3) polycrystalline thermoluminescence (TL) phosphor doped with rare earth (RE3+) elements has been synthesized by high temperature solid state diffusion reaction. The reaction has produced a very stable crystalline LiCaBO3:RE3+ phosphors. Among these RE3+ doped phosphors thulium doped material showed maximum TL sensitivity with favorable glow curve shape. TL glow curve of gamma irradiated LiCaBO3:Tm3+ samples had shown two major well-separated glow peaks at 230 and 430 °C. The glow peak at 430 °C is almost thrice the intensity of the glow peak at 230 °C. The TL sensitivity of the phosphor to gamma radiation was about eight times that of TLD-100 (LiF). Photoluminescence and TL emission spectra showed the characteristic Tm3+ peaks. TL response to gamma radiation dose was linear up to 103 Gy. Post-irradiation TL fading on storage in room temperature and elevated temperatures was studied in LiCaBO3:Tm3+ phosphor. 相似文献
9.
By using diamond anvil cell (DAC), high-pressure Raman spectroscopic studies of orthophosphates Ba3(PO4)2 and Sr3(PO4)2 were carried out up to 30.7 and 30.1 GPa, respectively. No pressure-induced phase transition was found in the studies. A methanol:ethanol:water (16:3:1) mixture was used as pressure medium in DAC, which is expected to exhibit nearly hydrostatic behavior up to about 14.4 GPa at room temperature. The behaviors of the phosphate modes in Ba3(PO4)2 and Sr3(PO4)2 below 14.4 GPa were quantitatively analyzed. The Raman shift of all modes increased linearly and continuously with pressure in Ba3(PO4)2 and Sr3(PO4)2. The pressure coefficients of the phosphate modes in Ba3(PO4)2 range from 2.8179 to 3.4186 cm−1 GPa−1 for ν3, 2.9609 cm−1 GPa−1 for ν1, from 0.9855 to 1.8085 cm−1 GPa−1 for ν4, and 1.4330 cm−1 GPa−1 for ν2, and the pressure coefficients of the phosphate modes in Sr3(PO4)2 range from 3.4247 to 4.3765 cm−1 GPa−1 for ν3, 3.7808 cm−1 GPa−1 for ν1, from 1.1005 to 1.9244 cm−1 GPa−1 for ν4, and 1.5647 cm−1 GPa−1 for ν2. 相似文献
10.
K. N. Shinde I. M. Nagpure S. J. Dhoble S. V. Godbole M. K. Bhide 《Indian Journal of Physics》2009,83(4):503-509
Ultrafine M5(PO4)3F:Dy3+ (M = Ca, Ba) phosphors were prepared via combustion process using metal nitrates as precursors. The formation of crystalline phosphate was confirmed by X-ray diffraction
pattern. The PL excitation spectra show the excitation peaks observed at 250 to 400 nm due to f → f transition of Dy3+ ion, which are useful for solid-state lighting purpose (mercury free excitation). The PL emission of Dy3+ ion by 348 nm excitation gave an emission at 489 nm (blue), 582 nm (yellow) and 675 nm (red). All the characteristics of
BYR emissions like BGR indicate that Dy doped Ca5(PO4)3F and Ba5(PO4)3F phosphors are good candidates that can be applied in solid-state lighting phosphor (mercury free excited lamp phosphor)
and white light LED.
相似文献
11.
The present paper reports that TL glow curve and kinetic parameter of Eu3+ doped SrY2O4 phosphor irradiated by beta source. Sample was prepared by solid state preparation method. Sample was characterized by XRD analysis and particle size was calculated by Debye–Scherrer formula. The sample was irradiated with Sr-90 beta source giving a dose of 10 Gy and the heating rate used for TL measurements are 6.7 °C/s. The samples display good TL peaks at 106 °C, 225 °C and 382 °C. The corresponding kinetic parameters are calculated. The photoluminescence excitation spectrum at 247 and 364 nm monitored with 400 nm excitation and the corresponding emission peaks at 590, 612 and 624 nm are reported. 相似文献
12.
A new phosphor in the Cl-F system doped with Dy, Ce and Eu has been reported. Characterization of this phosphor using XRD, PL and TL techniques is described. Polycrystalline Na6(SO4)2FCl:Dy; Na6(SO4)2FCl:Ce and Na6(SO4)2FCl:Eu phosphors prepared by a solid state diffusion method have been studied for their X-ray diffraction, photoluminescence (PL) and thermoluminescence (TL)characteristics. The PL excitation and emission spectra of phosphors were obtained. Dy3+ emission in the host at 475 and 570 nm is observed due to 4F9/2→6H15/2 and 4F9/2→6H13/2 transition, respectively, whereas the PL emission spectra of Na6(SO4)2FCl:Ce phosphor shows the Ce3+ emission at 322 nm due to 5d→4f transition of Ce3+ ion. In Na6(SO4)2FCl:Eu lattice, Eu2+ as well as Eu3+ emissions are observed. The emission of europium ion in this compound exhibits the blue as well as red emission. The TL glow curves of the same compounds have the simple structure with a prominent peak at 150, 175 and 200 °C. TL response, fading, reusability and trapping parameters of the phosphors are also studied. The TL glow curves of γ-irradiated Na6(SO4)2FCl sample show one glow peak indicating that only one set of traps is being activated within the particular temperature range each with its own value of activation energy (E) and frequency factor (s). The trapping parameters associated with the prominent glow peak are calculated using Chen’s half width method. The release of hole/electron from defect centers at the characteristic trap site initiates the luminescence process in these materials. The intensity of the TL glow peaks increases with increase of the added γ-ray dose to the samples. 相似文献
13.
Eu3+-doped LiGd(MoO4)2 red phosphor was synthesized by solid-state reaction, and its photoluminescent properties were measured. The effect of Eu3+ doping concentration on PL intensity was investigated, and the optimum concentration of Eu3+ doped in LiGd(MoO4)2 was found to be 30 mol%. Compared with Y2O2S:0.05Eu3+, Na0.5Gd0.5MoO4:Eu3+ and KGd(MoO4)2:Eu3+, the LiGd(MoO4)2:Eu3+ phosphor showed a stronger excitation band around 395 nm and a higher intensity red emission of Eu3+ under 395 nm light excitation. For the first time, intensive red light-emitting diodes (LEDs) were fabricated by combining phosphor and a 395 nm InGaN chip, confirming that the LiGd(MoO4)2:Eu3+ phosphor is a good candidate for LED applications. 相似文献
14.
A blue phosphor, BaMgAl10O17:Eu2+, has been synthesized in the furnace at a temperature of 500 °C by solution combustion method. The formation of the as-prepared BaMgAl10O17:Eu2+ phosphor was confirmed by the powder X-ray diffraction technique. The EPR spectrum exhibited an intense resonance signal centered at g=4.63 at 150 mT along with a number of resonances in the vicinity of g>2.0 and g<2.0. The number of spins participating in resonance (N) and the susceptibility (c) for the resonance signal at g=4.63 have been calculated as a function of temperature. The excitation spectrum of BaMgAl10O17:Eu2+ phosphor showed a strong peak near 336 nm (4f7 (8S)→5d1(t2g) transition) with a staircase like structure in the region 376-400 nm owing to crystal field splitting of the Eu2+ d-orbital. The 336 nm excitation produced a broad blue emission at 450 nm corresponding to 4f65d→4f7 transition. PL studies reveal the two emission centers one at 450 nm and the other at 490 nm in this phosphor. 相似文献
15.
Sr3MgSi2O8:Eu2+ and Sr2MgSi2O7:Eu2+ phosphors find uses in applications such as plasma display panel (PDP), solid-state lighting, longafter glow. Preparation of these phosphors by a modified combustion synthesis is described in this paper. As-prepared samples did not show photoluminescence. After reducing the samples at 900 °C, characteristic Eu2+ emission was observed. Preparation of these phosphors by using similar methods helped clarifying various results obtained for Sr3MgSi2O8:Eu2+ by different investigators. 相似文献
16.
Hyoung Sun Yoo Won Bin Im Sung Wook Kim Byoung Hwa Kwon Duk Young Jeon 《Journal of luminescence》2010,130(1):153-156
In order to investigate the effects of the crystallite size on the photoluminescence (PL) properties of a phosphor, monodisperse spherical SiO2/Y2O3:Eu3+ phosphor core/shell particles were synthesized. On the surface of the core particles prepared by the Stöber method, the phosphor shell was continuously coated by a heterogeneous precipitation method. Because the growth of the crystallite was restricted by the shell thickness, the crystallite size could be successfully controlled at the same firing conditions. The PL intensity, the asymmetric ratio and thus the color purity were significantly decreased with the decrease of the crystallite size. In addition, the position of charge transfer band in the PL excitation spectrum was red-shifted with the decrease of the crystallite size. 相似文献
17.
Blue and green double emitting phosphor, Ce3+ and Tb3+ co-doped NaSr4(BO3)3, was synthesized in a weak reducing atmosphere by a conventional high temperature solid-state reaction technique. For comparison, Ce3+ or Tb3+ singly doped NaSr4(BO3)3 was also prepared. The emission and excitation spectra of all samples have been investigated. NaSr4(BO3)3:Tb3+ excitation includes a strong absorption at about 240 nm and some weak sharp lines in near-ultraviolet (n-UV) spectral region. The excitation of Ce3+ and Tb3+ co-doped NaSr4(BO3)3 shows a strong broad band absorption in the n-UV region from the contribution of Ce3+, which makes it suitable for excitation by a n-UV LED chip. The emission of NaSr4(BO3)3:Ce3+,Tb3+ consists of a blue emission band from Ce3+ and a green emission from Tb3+ under the excitation of n-UV light. Energy transfer between Ce3+ and Tb3+ is also discussed, and the relative intensity of blue emission and green emission could be tuned by adjusting the concentration of Ce3+ and Tb3+. The phosphor NaSr4(BO3)3:Ce3+,Tb3+ could be considered as a double emission phosphor for n-UV excited white light-emitting diodes. 相似文献
18.
测量了碱土金属正磷酸盐Ba3(PO4)2和Sr3(PO4)2常温及高温拉曼光谱, 对拉曼振动模式进行指认, 并分析了晶体拉曼振动光谱及晶体结构在高温下的变化. 在温度升高的过程中, 拉曼振动频率向低频移动且振动峰宽度展宽, 晶体中的P-O平均键长随温度升高而变长, 但O-P-O的键角并未发生变化. 晶体在900 ℃以下无结构相变发生.
关键词:
3(PO4)2和Sr3(PO4)2')" href="#">Ba3(PO4)2和Sr3(PO4)2
高温拉曼光谱
振动模式
高温结构 相似文献
19.
Electron spin resonance spectra of manganese-doped calcium hydroxide were studied at room temperature for Mn concentrations between 0.01 and 2.00 mol%. The results suggest that the range of the exchange interaction between Mn2+ ions is about 1.05 nm. 相似文献
20.
T. Kaji H. Ohta Y. Inagaki M. Azuma 《Journal of Physics and Chemistry of Solids》2005,66(11):2068-2071
Submillimeter and millimeter wave ESR measurements of spin gap systems SrCu2(PO4)2 and PbCu2(PO4)2, which have four kinds of dimers, have been performed to investigate the magnetic properties of spin gap systems using the pulsed magnetic field up to 35T. The observed ESR spectra of powder sample SrCu2(PO4)2 show sharp and single peak in the temperature range from 4.2 to 80 K. The anisotropy of the g-values turned out to be very small compared to the usual anisotropic powder spectra of copper compounds. The dynamical properties will be discussed from the temperature dependence measurements. 相似文献