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1.
《Optical Materials》2010,32(12):1787-1790
Up-converting yttrium oxysulfide nanomaterials doped with ytterbium and erbium (Y2O2S:Yb3+,Er3+) were prepared with the flux method. The precursor oxide materials were prepared using the combustion synthesis. The morphology of the oxysulfides was characterized with transmission electron microscopy (TEM). The particle size distribution was 10–110 nm, depending on the heating temperature. According to the X-ray powder diffraction (XPD), the crystal structure was found hexagonal and the particle sizes estimated with the Scherrer equation agreeded with the TEM images. Upon the 970 nm infrared (IR) laser excitation, the materials yield moderate green ((2H11/2, 4S3/2)  4I15/2 transition) and strong red (4F9/2  4I15/2) luminescence. The green luminescence was enhanced with respect to the red one by an increase in both the crystallite size and erbium concentration due to the cross-relaxation (CR) processes. The most intense up-conversion luminescence was achieved with xYb and xEr equal to 0.10 and 0.005, respectively. Above these concentrations, concentration quenching occurred.  相似文献   

2.
Emission properties of Ho3+ at 2.0 μm and the energy transfer mechanism between Yb3+, Er3+ and Ho3+ ions in fluorophosphate glasses are investigated. The measured emission spectra show that the 5I7 → 5I8 transition of Ho3+ upon 980 nm laser diode excitation is strong. Judd–Ofelt intensity parameters (Ωλ, λ = 2, 4, 6), spontaneous transition probability (Arad), radiative lifetime (τr), absorption cross section (σa), stimulated emission cross section (σe) and FWHM ×  for the transition of Ho3+: 5I7 → 5I8 are calculated and discussed. The obtained results show that the present Yb3+/Er3+/Ho3+ triply-doped fluorophosphate glass can be identified to be a promising material at 2.0 μm emission.  相似文献   

3.
Optical transition intensity parameters of Er3+ in ZBLAN were carefully calculated, and the obtained results were compared with those reported by others. The emission cross sections of 4S3/2 → 4I13/2 and 4I11/2 → 4I13/2 transitions were confirmed according to the Fuchtbauer–Ladenburg (FL) formula. The excited state absorption cross sections for 4I13/2 → 4S3/2 and 4I13/2 → 4I11/2 transitions were derived by using the reciprocity relationship in the framework of McCumber theory. The laser gain properties of 4S3/2 → 4I13/2 and 4I11/2 → 4I13/2 transitions were discussed.  相似文献   

4.
Yb3+/Er3+ codoped BaGd2(MoO4)4 phosphor powders were prepared by the Sol-gel method and the upconversion luminescence properties were investigated in detail. Under 980 nm semiconductor laser excitation, BaGd2(MoO4)4:Yb3+,Er3+ phosphor exhibits green upconversion luminescence with peaks at 530 and 550 nm, which are due to the transitions of Er3+ (2H11/2) → Er3+ (4I15/2) and Er3+ (4S3/2) → Er3+ (4I15/2), respectively. Both of the two green emission lines are produced by populating Er3+ ions to the excited state through a two-photon process. By monitoring the intensities of the green upconversion luminescence, the optimum conditions for the Sol-gel synthesis were determined when the molar ratio of citric acid to total chelate metal cations was 2:1 and the sintering temperature was at 1073 K. The concentration quenching effect for Er3+ was found at the optimum doping concentration of 6 mol%, and the critical distance for the neighboring Er3+ was determined to be about 21.5 Å.  相似文献   

5.
Synthesis and upconversion luminescence properties of the new BaGd2(MoO4)4:Yb3+,Er3+ phosphor were reported in this paper. The phosphor powder was obtained by the traditional high temperature solid-state method, and its phase structure was characterized by the XRD pattern. Based on the upconversion luminescence properties studies, it is found that, under 980 nm semiconductor laser excitation, BaGd2(MoO4)4:Yb3+,Er3+ phosphor exhibits intense green upconversion luminescence, which is ascribed to 2H11/2 → 4I15/2 and 4S3/2 → 4I15/2 transition of Er3+. While the observed much weaker red emission is due to the non-radiative relaxation process of 4S3/2 → 4F9/2 and 4F9/2 → 4I15/2 transition originating from the same Er3+. The concentration quenching effects for both Yb3+ and Er3+ were found, and the optimum doping concentrations of 0.5 mol% Yb3+ and 0.08 mol% Er3+ in the new BaGd2(MoO4)4 Gd3+ host were established.  相似文献   

6.
Transparent oxyfluoride nano-glass–ceramics 90(SiO2)10(PbF2) co-doped with 0.3 Yb3+ and 0.1 Er3+ (mol%) have been prepared by thermal treatment of precursor sol–gel glasses. X-ray diffraction and high resolution transmission electron microscopy analysis pointed out a precipitation of cubic β-PbF2 nanocrystals of certain diameter in nano-glass–ceramics varying from 10 to 20 nm depending on heat treatment conditions. The incorporation of Yb3+ and Er3+ dopants in these nanocrystals has been confirmed by signatures of luminescence spectroscopy. Up-conversion luminescence pumped at 980 nm has been detected. Colour tuneability of up-conversion luminescence varying pump power has been analyzed in terms of standard chromaticity diagram. This tuneability opens applications for up-conversion phosphors and three-dimensional optical recording.  相似文献   

7.
Er3+ doped SrF2–SiO2 transparent glass ceramics were prepared by sol–gel method and heat treatment. The decomposition of Sr2+–CF3COO and the formation of SrF2 nano-crystals were found to proceed synchronously in the xerogel. After crystallization of the xerogel, SrF2 nano-crystals with 8–10 nm in size distributed homogenously among the glassy matrix, and the microstructure of the glass ceramic was stable under and at the temperature of 800 °C probably due to interfacial interaction between nano-crystals and glassy matrix. When heat-treated at 800 °C, the chemically bonded water in the sample was eliminated, resulting in the appearance of the visible luminescence bands of 2H11/2, 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2 transitions.  相似文献   

8.
Phosphate glasses in the compositions of 70P2O5–15Al2O3–14Na2O–1RE3+ (RE = Sm, Dy, and Tm) (mol%) were prepared by melt-quenching technique and characterized optically. The differential thermal analysis (DTA) profile of the host glass was carried out to confirm its thermal stability. For all the glasses absorption, photoluminescence and decay measurements have also been carried out. These glasses have shown strong emission and absorption bands in visible and near-infrared (NIR) region. From the measured absorption spectra, Judd–Ofelt (J–O) intensity parameters (Ω2, Ω4 and Ω6) have been calculated for all the studied ions. For Sm3+ doped glass, four emission bands centered at 562 nm (4G5/2 → 6H5/2), 598 nm (4G5/2 → 6H7/2), 644 nm (4G5/2 → 6H9/2), and 704 nm (4G5/2 → 6H11/2) have been observed with 402 nm (6H5/2 → 4F7/2) excitation wavelength. Of them, 598 nm (4G5/2 → 6H7/2) has shown a bright orange emission. With regard to Dy3+ doped glass, a blue emission band centered at 486 nm (4F9/2 → 6H15/2) and a bright yellow emission at 575 nm (4F9/2 → 6H13/2) have been observed, apart from 662 nm (4F9/2 → 6H11/2) emission transition with an excitation at 388 nm (6H15/2 → 4I13/2,4F7/2) wavelength. Emission bands of 650 nm (1G4 → 3F4) and 785 nm (1G4 → 3H5) transitions for the Tm3+ doped glass, with an excitation wavelength at 466 nm (3H6 → 1G4), have also been observed. The stimulated emission cross-sections of all the emission bands of RE3+ glasses (RE = Sm, Dy, and Tm) have been computed based on their measured full-width at half maximum (FWHM, Δλ) and measured lifetimes (τm).  相似文献   

9.
Up-converting NaYF4:Yb3+,Er3+ (xYb: 0.20, xEr: 0.02) nanomaterials were prepared with a microwave assisted solvothermal synthesis to study how the synthesis parameters affect the structure and up-conversion luminescence of the materials and thus their usability as labels in biomedical applications. The purity of the materials was studied with Fourier transform infra-red (FT-IR) spectroscopy and the particle size and morphology with transmission electron microscopy (TEM). The crystal structure was characterized with X-ray powder diffraction (XPD) and the crystallite sizes were calculated with the Scherrer formula. Up-conversion luminescence and luminescence decays were studied with near infra-red (NIR) laser excitation at 970 nm.The presence of the oleic acid was observed in the FT-IR spectra. The TEM images showed small quasi-spherical nanoparticles as well as long nanorods. The XPD measurements revealed that both cubic and hexagonal forms of NaYF4 were present in the materials. The crystallite sizes ranged from ca. 20 to over 150 nm for the cubic and hexagonal phases, respectively. The characteristic up-conversion luminescence of Er3+ in red (640–685 nm; 4F9/2  4I15/2) and green (515–560 nm; 2H11/2, 4S3/2  4I15/2 transitions) wavelengths was observed. The most intense luminescence and the longest luminescence emission lifetime were obtained with the material annealed for 12 h at 177 °C with 1.8 MPa pressure due to the predominance of the well-crystallized hexagonal form of NaRF4 (R: Y, Yb, Er).  相似文献   

10.
Different crystal structure of TeO2 nanoparticles were used as the host materials to prepare the Er3+/Yb3+ ions co-doped upconversion luminescent materials. The TeO2 nanoparticles mainly kept the original morphology and phase after having been co-doped the Er3+/Yb3+ ions. All the as-prepared TeO2:Er3+/Yb3+ nanoparticles showed the green emissions (525 nm, 545 nm) and red emission (667 nm) under 980 nm excitation. The green emissions at 525 nm, 545 nm and red emission at 667 nm were attributed to the 2H11/2 → 4I15/2, 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2 transitions of the Er3+ ions, respectively. For the α-TeO2:Er3+/Yb3+ (3/10 mol%) nanoparticles, three-photon process involved in the green (2H11/2 → 4I15/2) emission, while two-photon process involved in the green (4S3/24I15/2) and red (4F9/2 → 4I15/2) emissions. For the β-TeO2:Er3+/Yb3+ (3/10 mol%) nanoparticles, two-photon process involved in the green (2H11/2 → 4I15/2), green (4S3/2 → 4I15/2) and red (4F9/2 → 4I15/2) emissions. It suggested that the crystal structure of TeO2 nanoparticles had an effect on transition processes of the Er3+/Yb3+ ions. The emission intensities of the α-TeO2:Er3+/Yb3+ (3/10 mol%) nanoparticles and β-TeO2:Er3+/Yb3+ (3/10 mol%) nanoparticles were much stronger than those of the (α + β)-TeO2:Er3+/Yb3+ (3/10 mol%) nanoparticles.  相似文献   

11.
Yb3+/Er3+ codoped Ca0.65La0.35F2.35 materials with intense red emission via upconversion were prepared by a high temperature solid-state method. Based on the upconversion luminescence properties investigations, it was found that, under 980 nm excitation, Ca0.65La0.35F2.35:20 mol.%Yb3+, xEr3+ showed intense red upconversion luminescence, which was ascribed to 4F9/2 → 4I15/2 transition of Er3+, although both green and red emissions could be detected. It was also found that the green and red emissions originated the two photon processes, and the ground-state absorption (GSA), excited-state absorption (ESA) and energy transfer (ET) processes between Er3+/Yb3+ ions and Er3+/Er3 ions were involved in the enhanced red emission mechanism.  相似文献   

12.
YVO4 single crystals doped with Ce3+, Er3+ and Yb3+ ions were grown by the Czochralsski technology. The luminescence properties of Er3+/Yb3+:YVO4 single crystals with different concentration of Ce3+ were studied, and the energy transfer mechanism between Er3+, Yb3+ and Ce3+ was discussed based on their energy level properties. The branching ratios of the 4I11/2 → 4I13/2 transition in different samples were calculated. The results indicate that codopants of Ce3+ greatly enhance the population rate of the 4I13/2 level due to the fast resonant energy transfer between Er3+ and Ce3+, i.e., 4I11/2(Er3+) + 2F7/2(Ce3+) → 4I13/2(Er3+) + 2F5/2(Ce3+).  相似文献   

13.
Structural and spectroscopic investigation of NaLaF4:Er3+ material at different doping concentrations is presented. X-ray diffraction patterns, up-conversion luminescence spectra and decay curves for 2H9/24I15/2, 4S3/24I15/2 and 4F9/24I15/2 optical transitions in the material are shown and possible excitation routes are discussed. Raman spectrum for the undoped material is presented and the effective phonon energy of the material is estimated. Based on the obtained results application of rare-earth doped NaLaF4 in the field of up-conversion phosphors is evaluated.  相似文献   

14.
The effect of temperature on the luminescence intensity of up-conversion and near infrared in Er3+/Yb3+ co-doped phosphate glass ceramics has been investigated. Efficient green and red up-conversion luminescence and strong infrared fluorescence at 1.54 μm wavelength are observed under excitation of 975 nm. The fluorescence intensity is changing at different temperature and the results are explained with the level transitions in Er3+/Yb3+ co-doped system. Meanwhile, the lifetime of Er3+:4I13/2 level corresponding to different operating temperature and pump power is also discussed, and the experimental results are fitted using multiphonon relaxation theory.  相似文献   

15.
Infrared to visible upconversion luminescence has been investigated in Er3+/Yb3+ co-doped CeO2 inverse opal. Under the excitation of 980 nm diode lasers, visible emissions centered at 525, 547, 561, 660 and 680 nm are observed, which are assigned to the Er3+ transitions of 2H11/2 → 4I15/2 (525 nm), 4S3/2 → 4I15/2 (547, 561 nm), 4F9/2 → 4I15/2 (660 and 680 nm), respectively. The effect of photonic band gap on the upconversion luminescence intensity was also obtained. Additionally, the upconversion luminescence mechanism was studied. The dependence of Er3+ upconversion emission intensity on pump power reveals that it is a two-photon excitation process.  相似文献   

16.
A large family of Sn2yPb2(1−y)P2S6xSe6(1−x) semiconductor-ferroelectric crystals were obtained by the Bridgman technique. The photoluminescence properties of the Sn2yPb2(1−y)P2S6xSe6(1−x) family crystals strongly depend on their chemical composition, excitation energy and temperature. The influence of the Pb → Sn and S → Se isovalent substitutions on the luminescence properties of a crystal with the Sn2P2Se6 basic composition was investigated. A broad emission band observed in the Sn2P2Se6 crystal with a maximum roughly at 600 nm (at T = 8.6 K) was assigned to a band-to-band electron-hole recombination, whereas broad emission bands, peaked near 785 nm (at T = 8.6 K) and 1025 nm (at T = 44 K) were assigned to an electron-hole recombination from defect levels localised within the bandgap. Possible types of recombination defect centres and specific mechanisms of luminescence in the Sn2P2Se6 semiconductor-ferroelectric crystals were considered and discussed on the basis of the obtained results and the referenced data.  相似文献   

17.
The Y2O2S:Eu3+,Mg2+,TiIV (xEu = 0.028, xMg = 0.086, xTi = 0.03) materials were prepared with the flux fusion method. According to X-ray powder diffraction, the materials had the hexagonal crystal structure. The emission of Y2O2S:Eu3+,Mg2+,TiIV was centered at 627 nm (λexc : 250 nm) due to the 5D0 → 7F2 transition of Eu3+. The excitation spectra (λem : 627 nm) showed broad bands at 240 and 320 nm due to the O2− → Eu3+ and S2− → Eu3+ charge transfer transitions, respectively. The latter band can also overlap with the Ti → Eu3+ energy transfer. In the excitation spectra with synchrotron radiation, in addition to the O2− → Eu3+ and S2− → Eu3+ charge transfer transitions, excitation over the band gap was observed at 4.8 eV (258 nm). The red persistent luminescence due to the 5D0 → 7F2 emission from Eu3+ residing in the regular Y3+ site of the host was ca. 10 min with 1 min fluorescent lamp irradiation. In addition, a very broad band was observed at 600 nm probably due to the Ti3+ emission.  相似文献   

18.
This paper presents the characterization of single-mode waveguides for 980 and 1550 nm wavelengths. High quality planar waveguide structure was fabricated from Y1 − xErxAl3(BO3)4 multilayer thin films with x = 0.02, 0.05, 0.1, 0.3, and 0.5, prepared through the polymeric precursor and sol-gel methods using spin-coating. The propagation losses of the planar waveguides varying from 0.63 to 0.88 dB/cm were measured at 632.8 and 1550 nm. The photoluminescence spectra and radiative lifetimes of the Er3+ 4I13/2 energy level were measured in waveguiding geometry. For most samples the photoluminescence decay was single exponential with lifetimes in between 640 μs and 200 μs, depending on the erbium concentration and synthesis method. These results indicate that Er doped YAl3(BO3)4 compounds are promising for low loss waveguides.  相似文献   

19.
20.
Tao Pang  Yao Fu  Xi-xian Luo 《Materials Letters》2008,62(16):2500-2502
The up-conversion luminescence properties of trivalent-rare-earth ion-doped orthotantalates are studied under 980 nm laser diode excitation. The results indicate that YTaO4:Tm3+/Yb3+ emits blue and strong infrared emissions respectively corresponding to 1G43H6 and 3H43H6 transitions of Tm3+ ions, while YTaO4:Er3+/Yb3+ produces strong green and weak red emissions, resulting from 2H11/2/4S3/24I15/2 and 4F9/24I15/2 transitions of Er3+ ions, respectively. In contrast to three excellent up-conversion phosphors, viz. NaYF4:Er3+/Yb3+, Y2O2S:Er3+/Yb3+ and Y2O3:Er3+, YTaO4:Er3+/Yb3+ shows not only strong green emission, but also larger intensity ratio of green to red emission. In addition, it is found that LaTaO4: Er3+/Yb3+ shows the minimum quenching concentration of Yb3+ and weakest up-conversion emission intensity, and the main peak presents blue shift (8 nm/556 nm) as compared with YTaO4:Er3+/Yb3+ and GdTaO4:Er3+/Yb3+. The distinct luminescent characteristics of LaTaO4: Er3+/Yb3+ can be attributed to the larger difference of radius between doped ion and La3+ ion.  相似文献   

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