共查询到20条相似文献,搜索用时 31 毫秒
1.
A.M. Srivastava H.A. ComanzoS.J. Camardello M. AycibinU. Happek 《Optical Materials》2012,34(4):591-595
A systematic study of the excitation spectrum of TbX3 (X = Cl−, Br−, I−) is presented in this work. In general, the excitation spectra of TbX3 can be divided into three major regions: (1) the short-wave host lattice absorption region, (2) the intermediate absorption region where the Tb3+ 4f8 → 4f75d1 interconfigurational excitation transition are located, and (3) the long-wave excitation region where the Tb3+ 4f8 → 4f8 intraconfigurational excitation transition are located. The high spin and the low spin components of the Tb3+ interconfigurational excitation transition are clearly identified in the case of TbCl3. The luminescence of TbX3 (X = Cl−, Br−, I−) is dominated by emission transitions emanating from the Tb3+5D4 state. A comparative study of the optical properties of TbX3 (X = Cl−, Br−, I−) with the properties of the Tb3+ ion in several halide host lattices is presented. Further, a comparative study of the fundamental host lattice optical transitions in terbium halides and other halide materials is also presented. 相似文献
2.
In this paper we will present VUV spectroscopy experiments performed at the Superlumi station of Hasylab, DESY, Hamburg, on samples of BaF2 crystals activated with Ce and BaF2, (Ba,La)F2 crystals activated with Er. The results of these experiments include time resolved luminescence and luminescence excitation spectra obtained under wavelength selective VUV and UV excitation by pulsed synchrotron radiation.We will reveal the information provided by the VUV/UV excitation spectra of the Ce3+ 5d → 4f as well as Er3+ 4fn−15d → 4fn and 4fn → 4fn emissions on energy transfer mechanisms from the fluoride host to the rare earth ion. We will demonstrate that the fast energy transfer channels involve bound excitons while the generation of free electrons and holes leads to slower processes dependant on hole and/or electron trapping.We will demonstrate that differences between the excitation spectra of the 5d → 4f emission in Ce and 4f105d → 4f11 emission in Er activated BaF2 are generated by the coupling of the 4f → 5d transition to the 4f10 core of the Er3+ ion. We will also identify the additional band, absent for Ce, which is due to the exchange split high spin (HS) state of the 4f105d configuration responsible for the slow decay of the excited Er3+ ions in BaF2 and (Ba,La)F2.Finally we will provide evidence and explain why the dominant VUV 4f105d → 4f11 Er3+ emission in BaF2 is spin-forbidden and slow while in the mixed (Ba,La)F2 crystals it is spin-allowed and fast. 相似文献
3.
A novel yellowish green phosphor tervalent terbium (Tb3+) doped strontium molybdate (SrMoO4) was synthesized by conventional solid-state reaction method and its crystal structure and luminescent properties are investigated in this paper. The X-ray diffraction patterns (XRD) showed that the phosphor sintered at 750 °C for 3 h was a pure SrMoO4 phase. The excitation spectrum consisted of two bands and the two excitation peaks located at 375 nm and 488 nm respectively. The emission spectrum was composed of four narrow bands, in which the strongest emission was located at 548 nm. The particle size analysis indicated that the median particle size D50 = 2.89 μm and range of particle size distribution was narrow. These results showed that the SrMoO4:Tb3+ phosphor was a promising yellowish green phosphor for ultraviolet light emitting diode (UVLED) and blue LED based white LED. The appropriate concentration of Tb3+ was 5 mol% for the highest emission intensity at 548 nm. Natrium ion (Na+) was found to be a promising charge compensator for SrMoO4:Tb3+ phosphor. 相似文献
4.
A.M. Srivastava A.A. SetlurH.A. Comanzo W.W. BeersU. Happek P. Schmidt 《Optical Materials》2011,33(3):292-298
The photoluminescence and excitation spectra of Pr3+ activated LaPO4 has been investigated in the 1.6-300 K temperature region. At room temperature, the luminescence of LaPO4:Pr3+ is composed of the interconfigurational 4f15d1 → 4f2 emission transitions. However, in the 1.6-60 K temperature range, the emission spectrum also consists of the intraconfigurational emission transitions that emanate from the 1S0 state. A radiative lifetime of 145 ns is measured for the Pr3+1S0 → 1I6 emission transition in LaPO4. This is one of the shortest radiative lifetime observed for this transition in a solid. The energy position of the Pr3+1S0 state in LaPO4 is established by high-resolution emission spectrum at 46 375 ± 5 cm−1. A detailed analysis of the thermal quenching of the 1S0 lifetime and emission intensity is presented. It is proposed that the lowest energy state of the relaxed 4f15d1 configuration is situated energetically below that of the 1S0 state. 相似文献
5.
In this paper, a modified sol-gel method was employed to prepare nanostructured MgAl2O4 spinel powders doped with Tb3+ ions and thermally treated at 700 and 1000 °C for 3 h. The structural properties of the prepared at 700 and 1000 °C powders where characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). According to obtained XRD patterns the formation of single-phase spinels after calcination was confirmed. The XRD analyses demonstrated that the powders were single-phase spinel nanopowders with high crystallite dispersion. The Rietveld method was applied to calculate lattice parameters. The averaged spinel particle size was determined to be ∼10 nm for calcination at 700 °C and ∼20 nm at 1000 °C. The emission and excitation spectra measured at room and low temperature (77 K) for the samples calcined at 700 and 1000 °C demonstrated characteristic spectra of Tb3+ ions. The effect of MgAl2O4:Tb3+ grain sizes on luminescence properties was noticed. 相似文献
6.
RE3+-activated monoclinic Na3GdP2O8 (RE3+ = Tb3+, Dy3+, Eu3+, Sm3+) phosphors have been synthesized by a solid-state reaction method. Their photoluminescence properties in the vacuum ultraviolet (VUV) region were investigated. By analyzing their excitation spectra, the host-related absorption band was determined to be around 166 nm. The f-d transition bands and the charge transfer bands for Na3GdP2O8:RE3+ (RE3+ = Tb3+, Dy3+, Eu3+, Sm3+) were assigned and corroborated. For the sample Na3GdP2O8:5%Tb3+, the strong bands at around 202 and 221 nm are assigned to the 4f-5d spin-allowed transitions and the weak band at 266 nm is related to the spin-forbidden transition of Tb3+. For Na3GdP2O8:5%Dy3+, the broad band at 176 nm could be related to the f-d transitions of Dy3+ and the O2− → Dy3+ charge transfer band (CTB) besides the host-related absorption. In the excitation spectrum of Eu3+ doped sample, the O2− → Eu3+ CTB is observed to be at 245 nm. For the Sm3+ doped sample, the O2− → Sm3+ CTB is not distinguished obviously and is overlapped with the host-related absorption band. 相似文献
7.
The vacuum ultraviolet excited luminescent properties of Eu3+, Tb3+, Dy3+, Sm3+ and Tm3+ in the matrices of Ca4Y6(SiO4)6O were investigated. The bands at about 173 nm in the vacuum ultraviolet excited spectra were attributed to host lattice absorption of the matrix Ca4Y6(SiO4)6O. For Eu3+-doped samples, the O2− → Eu3+ CTB was identified at 258 nm. Typical 4f-5d absorption bands in the region of 195-300 nm were observed in Tb3+-doped samples. For Dy3+-doped and Sm3+-doped samples, the broad excitation bands consisted of host absorptions, CTB and f-d transition. For Tm3+-doped samples, the O2− → Tm3+ CTB was located at 191 nm. About the color purity and emission intensity, Ca4Y6(SiO4)6O:Tb3+ is an attractive candidate of green light PDP phosphor, and Ca4Y6(SiO4)6O:Dy3+ has potential application in the field of mercury-free lamps. 相似文献
8.
Aluminium oxide (Al2O3) films doped with CeCl3, TbCl3 and MnCl2 were deposited at 300 °C with the ultrasonic spray pyrolysis technique. The films were analysed using the X-ray diffraction technique and they exhibited a very broad band without any indication of crystallinity, typical of amorphous materials. Sensitization of Tb3+ and Mn2+ ions by Ce3+ ions gives rise to blue, green and red simultaneous emission when the film activated by such ions is excited with UV radiation. The overall efficiency of such energy transfer results to be about 85% upon excitation at 312 nm. Energy transfer from Ce3+ to Tb3+ ions through an electric dipole-quadrupole interaction mechanism appears to be more probable than the electric dipole-dipole one. A strong white light emission for the Al2O3:Ce3+(1.3 at.%):Tb3+(0.2 at.%):Mn2+(0.3 at.%) film under UV excitation is observed. The high efficiency of energy transfer from Ce3+ to Tb3+ and Mn2+ ions, resulting in cold white light emission (x = 0.30 and y = 0.32 chromaticity coordinates) makes the Ce3+, Tb3+ and Mn2+ triply doped Al2O3 film an interesting material for the design of efficient UV pumped phosphors for white light generation. 相似文献
9.
We present luminescence, luminescence excitation and luminescence time resolved spectra of La2Be2O5:Pr3+ system. We used high pressure spectroscopy approaches, with high pressure applied in diamond anvil cell (DAC) and sapphire anvil cell (SAC), for detailed analysis of luminescence related to the 4f5d → 4f2 and 4f2 → 4f2 transitions. We present effect of up-converted luminescence related to 4f5d → 4f2 transition excited with 488 nm. We also discussed possibility of existence of praseodymium trapped exciton (PTE) states in La2Be2O5:Pr3+ system. Lack of the PTE is attributed to high quantity of bulk modulus of this material. 相似文献
10.
Comparing the luminescence properties of nanosized and macroscopic LaPO4:Ce,Tb powders are performed in wide spectral range using synchrotron radiation. In the present study, LaPO4:Ce,Tb nanopowder was produced by means of a microwave-induced synthesis in ionic liquids, whereas the bulk sample represents a commercial lamp phosphor. Emission and excitation of both, Ce3+ and Tb3+ luminescence, is observed to be different when comparing bulk and nanosized LaPO4:Ce,Tb. In particular, it was shown that the fine structure of the Ce3+ as well as the Tb3+ related emission is poorly resolved for the nanomaterial. It is suggested that the nanoparticles surface plays a key role regarding the perturbation of rare-earth ions and changes their luminescence properties. Furthermore, it is demonstrated that allowed f-d transitions on Tb3+ at high energy are significantly suppressed for nanosized LaPO4:Ce,Tb. Energy transfer is required to initiate Tb3+ emission even in the vacuum ultraviolet spectral range. 相似文献
11.
A novel green phosphor Tb3+ doped AlPO4 was synthesized by conventional solid-state reaction method. The phosphor showed prominent luminescence in green due to the 5D4-7F5 transition of Tb3+. Structural characterization of the luminescent material was carried out with X-ray powder diffraction (XRD) analysis. The XRD measurements indicated that there are no crystalline phases other than AlPO4. Luminescence properties were analyzed by measuring the excitation and photoluminescence spectra. Photoluminescence measurements indicated that the phosphor exhibited bright green emission at about 542 nm under UV excitation. It is shown that the 3 mol% of doping concentration of Tb3+ ions in AlPO4:Tb3+ phosphor is optimum. The measured chromaticity for the phosphors AlPO4:Tb3+ under UV excitation is (0.32, 0.53). 相似文献
12.
Hongbin Liang Zifeng TianHuihong Lin Mubiao XieGuobin Zhang Pieter DorenbosQiang Su 《Optical Materials》2011,33(4):618-622
The spectroscopic properties of Na3Gd(PO4)2 and Na3Gd(PO4)2:Ce3+ phosphors in the VUV-UV spectral range were investigated. Five excitation bands of Ce3+ ions at Gd3+ sites are observed at wavelengths of 205, 246, 260, 292, and 321 nm. Doublet Ce3+ 5d → 4f emission bands are observed at 341 and 365 nm with a decay constant τ1/e around 26 ns. The X-ray excited luminescence of Na3Gd0.99Ce0.01(PO4)2 at room temperature shows a photon yield of ∼17,000 photons/MeV of absorbed X-ray energy. 相似文献
13.
The quenching concentrations of 5D4-7F6 emission of Tb3+ in (Gd,Y)BO3:Tb under 130-290 nm excitation were systematically investigated. The results revealed that its quenching concentrations of luminescence excited at particular wavelengths are dependent on corresponding excitation bands. Resulting in a calculation of coupling interaction, it was found that the quenching concentrations at excitation regions due to electrostatic interaction are often small while those corresponding to exchange interaction are usually larger (> 10%). Moreover, the quenching concentrations are also influenced significantly by luminescence sensitization of Gd3+ and Y3+ ions. Based on these results, a possible photoluminescence quenching mechanism was proposed. 相似文献
14.
Jianguo Zhao Weiying ZhangErqing Xie Zhongli LiuJianwu Feng Zhaojun Liu 《Materials Science and Engineering: B》2011,176(12):932-936
One-dimensional Tb3+-doped β-Ga2O3 nanofibers were prepared by a simple and cost-effective electrospinning process. Field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Raman technique, and photoluminescence (PL) were used to characterize the electrospun nanofibers. FE-SEM results indicated that the diameters all of the nanofibers ranged from 100 to 300 nm, and the lengths of nanofibers reached up to several millimeters. The XRD and Raman results showed that the Ga2O3 phase belongs to the monoclinic phase. Under ultraviolet excitation, the β-Ga2O3:Tb3+ samples showed green emission with the strongest peak at 550 nm, corresponding to 5D4 → 7F5 transition of Tb3+ ions. The luminescence intensity had been further studied as a function of the doping concentration of Tb3+ in the β-Ga2O3 samples. 相似文献
15.
Jinsheng Liao Bao Qiu Herui Wen Jinglin Chen Weixiong You 《Materials Research Bulletin》2009,44(9):1863-868
Tb3+-doped SrWO4 phosphors with a scheelite structure have been prepared by hydrothermal reaction. X-ray powder diffraction, field-emission scanning electron microscopy, photoluminescence excitation and emission spectra and decay curve were used to characterize the resulting samples. Scanning electron microscopy image showed that the obtained SrWO4:Tb3+ phosphors appeared to be nearly spherical and their sizes ranged from 1 to 3 μm. Photoluminescence spectra indicated the phosphors emitted strong green light centered at 545 nm under ultraviolet light excitation. Because 12 at.% SWO4:Tb3+ phosphor exhibits intensive green emission under 254 nm excitation in comparison with the commercial green fluorescent lamp phosphor (LaPO4:Ce,Tb), the excellent luminescence properties make it a new promising green phosphor for fluorescent lamps application. 相似文献
16.
Lianyun DengJingxuan Lei Ying Shi Ting LinYuying Ren Jianjun Xie 《Materials Letters》2011,65(4):769-771
Aluminum oxynitride(AlON) phosphors co-doped by Tb3+ and Ce3+ were synthesized by nitridation of the precursor which was co-precipitated from Al(NO3)3 solution and nanosized carbon black at 1750 °C for 2 "hrs" in flowing nitrogen atmosphere. The obtained AlON based powders were composed of polycrystalline spinel typed particles with sizes in the range of 1-3 μm. Under an excitation of 275 nm, it was found that co-doping of Ce3+ could drastically enhance the luminescence of AlON:Tb3+ powder by energy transfer. The product with 0.5 mol% Ce3+ and 0.67 mol% Tb3+ exhibited a strong broad green emission at 540 nm. The critical quenching concentration of Tb3+ in AlON:0.5 mol% Ce3+/xmol% Tb3+ phosphor was determined to be 0.67 mol%. It was supposed that the mechanism of concentration quenching of Tb3+ in AlON:0.5 mol% Ce3+ xmol% Tb3+ phosphor was dipole-dipole interaction. 相似文献
17.
In this work, two Tb3+ activated green phosphors: Y2O3:Tb3+ and YBO3:Tb3+ were prepared by hydrothermal method. Photoluminescence properties of both phosphors were studied in details. Both phosphors exhibit similar luminescent characteristics symbolized by the dominant green emission at 545 nm. Concentration quenching occurs at the Tb3+ concentration of 1.60 atomic% and 2.57 atomic% for Y2O3:Tb3+ and YBO3:Tb3+, respectively. Luminescence decay properties were characterized to better understand the mechanism of concentration quenching. Based on the calculation, the concentration quenching in both phosphors was caused by the dipole–dipole interaction between Tb3+ ions. 相似文献
18.
In the search for new scintillator materials, Ce3+ doped chlorides are a promising class of materials, combining a high efficiency and fast response time. Even shorter response times may be achieved by replacing Ce3+ by Pr3+ or Nd3+ as the lifetime of the d-f emission is substantially shorter for these ions. Here we report on the luminescence properties of Ce3+, Pr3+ and Nd3+ in RbCl and investigate the potential as a scintillator material. Under UV excitation Ce3+ shows d-f emission between 325 and 425 nm. The emission originates from multiple (differently charge compensated) Ce3+ sites. The luminescence lifetime varies with wavelength and is ∼40 ns for the longer wavelength emission. For RbCl:Pr3+ three d-f emission band are observed between 250 and 350 nm which can be assigned to transitions from the lowest energy fd state to different 3HJ (J = 4-6) states within the 4f2 configuration of Pr3+. The decay time is ∼17 ns. For the Nd3+ activated sample a weak emission band around 220 nm is observed only at 8 K which may be due to d-f emission. The very short lifetime (4 ns) is faster than the radiative lifetime, indicating that the d-f emission is quenched by relaxation to lower lying 4f3 states or by the process of photoionization. Under VUV excitation at wavelengths below 175 nm (the bandgap of RbCl) the d-f emission is very weak for Ce3+, Pr3+ and Nd3+ doped RbCl and the emission spectra are dominated by defect related emission. This indicates that energy transfer from the host lattice to the fd states is inefficient which prevents application as a scintillator material. 相似文献
19.
Ye Jin Zhendong HaoXia Zhang Yongshi LuoXiaojun Wang Jiahua Zhang 《Optical Materials》2011,33(11):1591-1594
Upon 4K11/2 excitation of Sm3+ at 405 nm, the performance of energy transfer from Sm3+ to Eu3+ in the red emitting phosphor CaMoO4:Eu3+, Sm3+ significantly extends its excitation region for better matching the near-UV LED. Photoluminescence spectra indicate that the energy transfer pathway concerns the relaxation from 4K11/2 to 4G5/2 of Sm3+ and subsequent transfer to 5D0 of Eu3+ rather than 5D1 of Eu3+. The fluorescent decay pattern of Sm3+4G5/2 level in CaMoO4:0.5% Sm3+, 2% Eu3+ is studied at 77 K based on the Inokuti-Hirayama formula, revealing an electronic dipole-dipole interaction between Sm3+ and Eu3+. The coefficient for the energy transfer is obtained to be 8.5 × 10−40 s−1 cm6. The fluorescence rise and decay pattern of Eu3+5D0 level as Sm3+ is only excited at 77 K is well described by the dynamical processes of the energy transfer. 相似文献
20.
A blue-emitting phosphor of NaMg4(PO4)3:Eu2+, Ce3+ was prepared by a combustion-assisted synthesis method. The phase formation was confirmed by X-ray powder diffraction measurement. Photoluminescence excitation spectrum measurements show that the phosphor can be excited by near UV light from 230 to 400 nm and presents a dominant luminescence band centered at 424 nm due to the 4f65d1 → 4f7 transition of Eu2+ ions at room temperature. Effective energy transfer occurs in Ce3+/Eu2+ co-doped NaMg4(PO4)3 due to large spectral overlap between the emission of Ce3+ and excitation of Eu2+. Co-doping of Ce3+ enhances the emission intensity of Eu2+ greatly by transferring its excitation energy to Eu2+, and Ce3+ plays a role as a sensitizer. Ce3+-Eu2+ co-doped NaMg4(PO4)3 powders can possibly be applied as blue phosphors in the fields of lighting and display. 相似文献