共查询到20条相似文献,搜索用时 46 毫秒
1.
Mitsuo Yamaga Hideaki Uno Shin-ichiro Tsuda Jon-Paul R. Wells Thomas P.J. Han 《Journal of luminescence》2012,132(6):1608-1617
Luminescence decay curves of Sm3+ ions in LiYF4 crystals doped with 1, 5 and 10 mol% Sm3+ are multi-exponential, whereas that in a LiYF4 crystal doped with 0.1 mol% Sm3+ is well approximated by a single exponential function with a decay time of 4.8 ms. The average luminescence decay times decrease from 4.8 to 0.60 ms with the increasing Sm3+ concentrations between 1 and 10 mol%. The decay curves for all crystals are found to be almost independent of the temperature between 15 and 300 K. The decrease of the decay times for the higher Sm3+ concentrations indicates energy transfer between two Sm3+ ions. Taking the crystal structure of LiYF4 into account, it is deduced that a single-step energy transfer process for the 1 and 5 mol% Sm3+ concentrations occurs from a Sm3+ ion at the origin of (0 0 0) to one of the Sm3+ ions substituting for the first nearest neighbor Y3+ sites and beyond within a sphere with an approximate radius of less than 0.7 nm. On the other hand, a multi-step energy transfer process dominates for the highest concentration (10 mol%) because the calculated average distance between two Sm3+ ions in the 10 mol% Sm3+ sample is comparable with the migration length of the single-step energy transfer process estimated from the 1 and 5 mol% Sm3+ samples. 相似文献
2.
Yannan Qian Rui Wang Lili Xing Yanling Xu Chunhui Yang 《Optics Communications》2012,285(13-14):2986-2989
The effect of Zn2+ ion on the dopant occupancy and optical characteristic of Er3+ ion in Er/Zn-codoped LiNbO3 crystal is reported. The intense 1.54 μm and relatively weak green upconversion emissions are observed for Er (1 mol%)/Zn (6 mol%):LiNbO3 crystal. The OH? absorption and the time-resolved spectra show that the Zn2+ codoping decreases the threshold concentration of Er3+ ion in Er/Zn-codoped LiNbO3 crystal. The experimental results here imply that the potential application of Er3+-doped LiNbO3 crystal can be designed and optimized on the basis of the theoretical investigations. 相似文献
3.
Photocatalytic degradation of methylene blue (MB) in water was examined using Er3+-doped TiO2 (Er–TiO2) nanorods prepared by a sol–gel derived electrospinning, calcination, and subsequent mechanical grinding. Different concentrations of Er dopant in the range of 0–1.0 mol% were synthesized to evaluate the effect of Er content on the photocatalytic activity of TiO2. Among Er3+–TiO2 catalysts, the 0.7 mol% Er3+–TiO2 catalyst showed the highest MB degradation rate. The degradation kinetic constant (k) increased from 1.0 × 10?3 min?1 to 5.1 × 10?3 min?1 with the increase of Er3+ doping from 0 to 0.7 mol%, but decreased down to 2.1 × 10?3 min?1 when Er3+ content was 1.0 mol%. It can be concluded that the degradation of MB under UV radiation was more efficient with Er3+–TiO2 catalyst than with pure TiO2. The higher activity might be attributed to the transition of 4f electrons of Er3+ and red shifts of the optical absorption edge of TiO2 by erbium ion doping. 相似文献
4.
P. Haro-González F. Lahoz J. González-Platas J.M. Cáceres S. González-Pérez D. Marrero-López N. Capuj I.R. Martín 《Journal of luminescence》2008,128(5-6):908-910
Measurements of the optical properties of Er3+ ions in strontium barium niobate glass and glass ceramics have been carried out. The glasses have been fabricated using a melt-quenching method, and the glass ceramic samples have been obtained from the glass precursor by a thermal treatment. The ceramic samples formed by a glassy phase, and a crystalline phase contains nanocrystals of Sr1?xBaxNb2O6 (SBN) doped with Er3+ ions with a mean size of ~50 nm, as confirmed with XRD. Green up-conversion emission has been obtained under excitation at 800 nm, and the temporal evolution of this emission has been reported with the purpose of determining the involved up-conversion mechanism. These optical measures have confirmed that the Er3+ ions have been incorporated into the SBN matrix, after a thermal treatment, which produced an increment of the up-conversion efficiency. 相似文献
5.
《Journal of luminescence》2003,65(2-4):127-133
BaMgAl10O17:Eu2+ (BAM) blue phosphor particles with improved photoluminescence (PL) intensity under vacuum ultraviolet (VUV) excitation were prepared by a spray pyrolysis process. In order to improve the PL intensity, Er3+ and Nd3+ ions were used as co-doping elements. The VUV characteristics of BAM:Eu2+, M+ (M=Er, Nd) were monitored with varying the Er3+ and Nd3+ content in order to find the optimal co-doping concentration when they were prepared by spray pyrolysis. It was found that doping Er3+ or Nd3+ enhances the PL intensity of BAM:Eu2+ blue phosphor particles. In particular, the M3+ doping effect on the PL intensity was pronounced when the prepared BAM:Eu2+, M3+ particles were excited by 172 nm VUV. The maximum intensity was obtained when the M3+ content was 1.0 at% with respect to Ba element. The PL intensity of BAM:Eu2+, M+ (M=Er3+, Nd3+) particles was also further improved by producing them in a spherical shape, which was successfully achieved by controlling the spray solution. The optimized BAM:Eu2+, M+ particles had about 10% higher PL intensity than that of the commercial particles, which are made by a conventional solid-state reaction. 相似文献
6.
This paper reports for the first time ultrasound, EGCG assisted synthesis of pure and Eu3+ (1–5 mol%) activated Ca2SiO4 nanophosphors having self-assembled superstructures with high purity. The shape, size and morphology of the product were tuned by controlling influential parameters. It was found that morphology was highly dependent on EGCG concentration, sonication time, pH and sonication power. The probable formation mechanism for various hierarchical superstructures was proposed. The PL studies of Ca2SiO4:Eu3+ phosphors can be effectively excited by the near ultraviolet (UV) (396 nm) light and exhibited strong red emission around 613 nm, which was attributed to the Eu3+ (5D0 → 7F2) transition. The concentration quenching phenomenon was explained based on energy transfer between defect and Eu3+ ions, electron–phonon coupling and Eu3+–Eu3+ interaction. The Judd–Ofelt intensity parameters and radiative properties were estimated by using PL emission spectra. The photometric studies indicate that the obtained phosphors could be a promising red component for possible applications in the field of white light emitting diodes. 相似文献
7.
The (GdxY1?x)2O3: Er3+, Yb3+ [x=0.0, 0.1, 0.5, 0.9, 1.0] phosphor samples with 0.5 mol% concentration of Er3+ and 3.0 mol% of Yb3+, have been prepared using combustion route. The effect of variation of composition on the morphology, crystallinity and photoluminescence characteristics of the material has been investigated. The samples were post-heated at a temperature 1200 °C, for 5 h. We find systematic color tunability from red to green with an increase of Gd2O3 content in Y2O3 lattice. Further, the post-heated samples show an enhancement of fluorescence intensity for more than fifteen times. The samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), photoluminescence measurement and Fourier transform infrared (FTIR) techniques in order to find out the structural changes in host lattice. An increase in crystallite size has been marked with increasing Gd content while FTIR analysis explains the reason of variation in the fluorescence of rare earth ions in different host matrices. 相似文献
8.
SrY2−x(MoO4)4:Er3+/Yb3 phosphors with doping concentrations of Er3+ and Yb3+ (x = Er3+ + Yb3+, Er3+ = 0.05, 0.1, 0.2 and Yb3+ = 0.2, 0.45) have been successfully synthesized by a cyclic microwave-modified sol–gel method, and the upconversion photoluminescence properties have been investigated. Well-crystallized particles showed a fine and homogeneous morphology with particle sizes of 1–3 μm. Under excitation at 980 nm, SrY2(MoO4)4:Er3+/Yb3+ particles exhibited a strong 525-nm, weak 550-nm emission bands in the green region, and a very weak 655-nm emission band in the red region. The possible mechanism of the green and red emissions was discussed in detail under consideration of a two-photon process. The Raman spectra of the particles indicated the presence of strong peaks at both higher and lower frequencies. 相似文献
9.
Thermo,Iono and photoluminescence properties of 100 MeV Si7+ ions bombarded CaSiO3:Eu3+ nanophosphor
D.V. Sunitha H. Nagabhushana Fouran Singh B.M. Nagabhushana S.C. Sharma R.P.S. Chakradhar 《Journal of luminescence》2012,132(8):2065-2071
This paper reports on the thermo (TL), iono (IL) and photoluminescence (PL) properties of nanocrystalline CaSiO3:Eu3+ (1–5 mol %) bombarded with 100 MeV Si7+ ions for the first time. The effect of different dopant concentrations and influence of ion fluence has been discussed. The characteristic emission peaks 5D0→7FJ (J=0, 1, 2, 3, 4) of Eu3+ ions was recorded in both PL (1×1011–1×1013 ions cm?2) and IL (4.16×1012–6.77×1012 ions cm?2) spectra. It is observed that PL intensity increases with ion fluence, whereas in IL the peaks intensity increases up to fluence 5.20×1012 ions cm?2, then it decreases. A well resolved TL glow peak at ~304 °C was recorded in all the ion bombarded samples at a warming rate of 5 °C s?1. The TL intensity is found to be maximum at 5 mol% Eu3+ concentration. Further, TL intensity increases sub linearly with shifting of glow peak towards lower temperature with ion fluence. 相似文献
10.
The Sm3+-doped lead fluorophosphate glasses of composition 44P2O5–17K2O–9Al2O3–(24?x)PbF2–6Na2O–xSm2O3, where x=0.01, 0.05, 0.1, 0.5, 1.0 and 2.0 mol%, have been prepared by conventional melt quenching technique and are characterized through differential thermal analysis, Raman, absorption and emission spectra and decay rate measurements. Free-ion Hamiltonian model for energy level analysis and Judd–Ofelt theory for spectral intensities have been used to analyze the spectroscopic properties of Sm3+ ions in lead fluorophosphate glasses. The decay rates for the 4G5/2 level of Sm3+ ions have been measured and are found to be single exponential at lower concentration (≤0.1 mol% Sm2O3) and turn into non-exponential at higher concentrations (≥0.5 mol% Sm2O3) due to energy transfer through cross-relaxation. The experimental lifetimes for 4G5/2 level of Sm3+ ions are found to decrease from 2.54 to 0.92 ms when the concentration increased from 0.01 to 2.0 mol% Sm2O3 due to energy transfer. In order to know the nature of the energy transfer mechanism, the non-exponential decay rates are well fitted to Inokuti–Hirayama model for S=6, which indicates that the energy transfer process is of dipole–dipole type. 相似文献
11.
Ru-Yuan Yang Min Hang Weng Huang-Yu Chen Chin-Min Hsiung Shin-Hung Chen 《Journal of luminescence》2012,132(2):478-483
This paper describes an investigation of the crystalline morphology and photoluminescent properties of YInGe2O7 powders doped with different Eu3+ concentrations using microwave assisted sintering and conventional sintering. X-ray powder diffraction analysis confirmed the formation of monoclinic YInGe2O7 structure as YInGe2O7:Eu3+ powders were sintered at 1200 °C in microwave furnace for 1 h, and the raw material phase of Y2O3 was observed when Eu3+ concentration was below 30 mol%. Scanning electron microscopy showed microwave assisted sintering results in smaller particle size and more uniform grain size distribution. In the photoluminescent (PL) studies, the concentration quenching effect was observed under the excitation at 393 nm, but not under the excitation at CTS band. The 5D0→7F2 transition (620 nm), exhibits a non-exponential decay behavior as YInGe2O7:Eu3+ powders were sintered by microwave with the Eu3+ concentration higher than 50 mol%. 相似文献
12.
Er3+ and Tm3+ singly doped and codoped new fluoride glasses were prepared by traditional melt-quenching method. Efficient 3 μm emission was obtained under 980 nm laser excitation. It is worthy to notice that one of the two ions can be the sensitizer to the other one by depressing the Er3+: 1.5 μm emission through the energy transfer process from Er3+:4I13/2 level to Tm3+:3F4 level. On the basis of measured absorption spectra, the Judd-Ofelt intensity parameters and radiation emission probability were calculated to evaluate the spectroscopic properties. Additionally, the micro-parameters together with the phonon assistance of Er3+:4I13/2 → Tm3+:3F4 and Er3+:4I11/2 → Tm3+:3H5 processes were quantitatively analyzed by using Dexter model. The theoretical micro-parameters results meet well with the experiments which indicates that Er3+/Tm3+ codoped fluoride glass is a potential kind laser glass for 3 μm laser. 相似文献
13.
《Journal of luminescence》2003,65(2-4):97-103
The luminescence and energy transfer processes in La2O3–Nb2O5–B2O3:M3+ (M=Bi, Eu, Dy) glasses were investigated using luminescence spectroscopy (excitation and emission, down to 4.2 K) and decay time measurements at room temperature. The observation of niobate luminescence implies a considerable degree of short- and intermediate-range order in these glasses. Energy transfer from the niobate groups to the lanthanide ions was observed for Eu3+, but not for Dy3+, suggesting that the energy transfer process occurs to the charge-transfer state of the Eu3+ ion, rather than to its f-levels. Inter-Eu3+ energy transfer was negligible in the concentration range investigated (up to 3 mol%). In contrast, cross-relaxation processes between Dy3+ ions were active at concentrations as low as 0.5 mol%. In the Bi3+ doped glasses the energy transfer was observed from the Bi3+ excited levels to the oxygen deficient niobate groups. 相似文献
14.
Luminescence and defect studies of YAlO3:Dy3+, Sm3+ single crystals exposed to 100 MeV Si7+ ion beam
H.B. Premkumar D.V. Sunitha Fouran Singh H. Nagabhushana S.C. Sharma B.M. Nagabhushana Guangjun Zhao Jianyu Chen R.P.S. Chakradhar 《Journal of luminescence》2012,132(10):2679-2683
Ionoluminescence (IL) and photoluminescence (PL) spectra for different rare earth ions (Sm3+ and Dy3+) activated YAlO3 single crystals have been induced with 100 MeV Si7+ ions with fluence of 7.81×1012 ions cm?2. Prominent IL and PL emission peaks in the range 550–725 nm in Sm3+ and 482–574 nm in Dy3+ were recorded. Variation of IL intensity in Dy3+ doped YAlO3 single crystals was studied in the fluence range 7.81×1012–11.71×1012 ions cm?2. IL intensity is found to be high in lower ion fluences and it decreases with increase in ion fluence due to thermal quenching as a result of an increase in the sample temperature caused by ion beam irradiation. Thermoluminescence (TL) spectra were recorded for fluence of 5.2×1012 ions cm?2 on pure and doped crystals at a warming rate of 5 °C s?1 at room temperature. Pure crystals show two glow peaks at 232 (Tg1) and 328 °C (Tg2). However, in Sm3+ doped crystals three glow peaks at 278 (Tg1), 332 (Tg2) and 384 °C (Tg3) and two glow peaks at 278 (Tg1) and 331 °C (Tg2) in Dy3+ was recorded. The kinetic parameters (E, b s) were estimated using glow peak shape method. The decay of IL intensity was explained by excitation spike model. 相似文献
15.
Ternary molybdate NaCaGd1−x(MoO4)3:Er3+/Yb3+ phosphors with the proper doping concentrations of Er3+ and Yb3+ (x = Er3+ + Yb3+, Er3+ = 0, 0.05, 0.1, 0.2 and Yb3+ = 0, 0.2, 0.45) were successfully synthesized by microwave sol–gel method for the first time. Well-crystallized particles formed after heat-treatment at 900 °C for 16 h showed a fine and homogeneous morphology with particle sizes of 3–5 μm. The optical properties were examined comparatively using photoluminescence emission and Raman spectroscopy. Under excitation at 980 nm, the doped particles exhibited a strong 525-nm emission band, a weak 550-nm emission band in the green region, which correspond to the 2H11/2 → 4I15/2 and 4S3/2 → 4I15/2 transitions, and a very weak 655-nm emission band in the red region, which corresponds to the 4F9/2 → 4I15/2 transition. The optimal Yb3+:Er3+ ratio was obtained to be 9:1, as indicated by the composition-dependent quenching effect of Er3+ ions. The pump power dependence of upconversion emission intensity and Commission Internationale de L’Eclairage chromaticity coordinates of the phosphors were evaluated in detail. 相似文献
16.
Yannan Qian Rui Wang Chao Xu Wei Xu Xiaohong Wu Lili Xing Yanling Xu 《Optics & Laser Technology》2012,44(7):2297-2301
The spectral characteristics of 1.54 μm emission in a series of Zn/Er:LiNbO3 crystals with heavy Er content and variable Zn content were reported. The inductively coupled plasma mass spectrometry (ICP-MS) was used to determine the concentration of Er3+ ion in the crystal. The absorption and emission spectra of Zn/Er:LiNbO3 crystals were measured. Based on Judd–Ofelt theory, the spectral parameters such as intensity parameters Ωt (t=2, 4 and 6), transition strengths, radiative transition probabilities, radiative lifetime and fluorescence branching ratio have been obtained in Zn/Er:LiNbO3 system. The emission cross section corresponding to 4I13/2→4I15/2 transition of Er3+ ion was obtained according to Füchtbauer–Ladenburg theory. The gain cross section of Er:LiNbO3 crystal codoped with 6 mol% Zn2+ ions were also discussed in this work. 相似文献
17.
The temperature of a transparent Cd0.7Sr0.3F2: Er3+(4%)–Yb3+(6%) crystalline plate 0.3 mm thick heated by a near-infrared (974 nm) laser diode and probed by a red (652 nm) laser was accurately evaluated as a function of the infrared power absorbed by the Yb3+ ions.The green emission generated by the Er3+ ions directly excited by the red laser consists of three major lines (coming from three individual Stark levels in thermal equilibrium) whose intensities were measured according to the absorbed infrared power and the distance between the heated and probed volumes, to evaluate the heating induced by the excitation of Yb3+ and Er3+ ions at 974 nm by applying the Boltzmann's equation linking the populations of emitting levels to the temperature. In the case where the Yb3+ ions excited by the laser diode are situated at a distance of about 0.5 mm from the edge of the crystal and for an absorbed infrared power of 100 mw, the crystal's edge temperature is reaching 80 °C after 20 s of continuous excitation at 974 nm. 相似文献
18.
Nadia G. Boetti Joris Lousteau Alessandro Chiasera Maurizio Ferrari Emanuele Mura Gerardo C. Scarpignato Silvio Abrate Daniel Milanese 《Journal of luminescence》2012,132(5):1265-1269
Er3+ doped niobic-tungsten–tellurite glasses doped with concentration of Er3+ ion up to 3 wt% were fabricated. The effect of Er3+ doping concentration on thermal stability and optical properties was investigated in order to obtain the most suitable rare earth content for developing 1.5 μm compact fiber amplifier pumped with a commercial telecom 980 nm laser diode. The maximum doping concentration allowed was found to be around 1.77×1020 ions/cm3, for which a broad 1.5 μm emission spectra of 65 nm FWHM and a lifetime of 3.4 ms for the 4I13/2 level was measured. 相似文献
19.
Bin Dong Zi-An Li Baosheng Cao Naisen Yu Mengtao Sun 《Optics Communications》2011,284(10-11):2528-2531
The quasi-one dimensional (Q1D) Er3+–Yb3+ codoped single-crystal MoO3 ribbons with width range from 1 to 5 μm, and maximum length about 30 μm have been synthesized by the vapor transport method. The samples were characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscope, and luminescence spectra. By a 975 nm laser diode (LD) as excitation source, the blue, green and red emission bands centered at about 408, 532, 553 and 657 nm were detected, which attributed to the 2H9/2 → 4I15/2, 2H11/2, 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2 transitions of Er3+, respectively. The three-, and two-photon process was responsible for the blue, green and red up-conversion emissions mechanism for the Q1D Er3+–Yb3+ codoped single-crystal MoO3 ribbons, respectively. The results suggested that the Q1D Er3+–Yb3+ codoped single-crystal MoO3 ribbons will have potential applications in remote bio-imaging and surface enhanced Raman scattering. 相似文献
20.
《Journal of magnetism and magnetic materials》2002,247(1):55-61
A study of the effect of annealing on the magnetic properties of single crystals Sn1−xEuxTe is reported. The width of the electron paramagnetic resonance line of the crystal is found to decrease upon annealing but its g-value of 1.991 is nearly unaffected. Magnetization results indicate that the pair exchange interaction is weakly antiferromagnetic with a value of −0.67 K for the non-annealed sample and −0.29 K after annealed sample. Susceptibility measurements performed as a function of temperature also indicate the presence of EuTe clusters in the as-grown Sn1−xEuxTe crystals. Therefore it was deduced that the Eu2+ ions tend to form clusters, particularly pairs, in the as-grown crystal and these clusters disappear after annealing, as the Eu2+ ions occupy isolated sites in the SnTe host lattice. 相似文献