Effect Of Yb3 Research Articles

Yb3+含量对掺Er3+铝酸盐玻璃光谱性质的影响

Yb3+含量对掺Er3+铝酸盐玻璃光谱性质的影响

Up- and Downconversion Luminescence in Ho<sup>3+</sup>,Yb<sup>3+</sup>-Co-Doped Y<sub>2</sub>O<sub>3</sub> Transparent Ceramics Prepared by Spark Plasma Sintering

We employed spark plasma sintering (SPS) in the presence of sintering aids to fabricate highquality Ho3+,Yb3+-co-doped Y2O3 transparent ceramics suitable for use as a laser gain medium, and analyzed their microstructure and optical properties. Ho3+,Yb3+-co-doped Y2O3 transparent ceramics with different contents of Yb3+ were fabricated by SPS and exhibited high transparency in both near-infrared and visible regions. All specimens showed high transparency in both the near-infrared and visible-light regions, and sample microstructure was almost unaffected by the amount of doped Yb3+. The transmission spectra of 1 mol% Yb3+ doped specimens exhibited transmissivities of 73.4 and 81.0% at wavelengths of 700 and 1500 nm, respectively. Relatively high transmissivity was quickly achieved through the addition of a sintering aid (1 mol% La2O3) which accelerated mass transport during sintering. The effect of Yb3+ doping on the upconversion photoluminescence of Y2O3:Ho3+,Yb3+ was examined. Irradiation at 980 nm resulted in strong green photoluminescence (552 nm) and weak red photoluminescence (669 nm). Excitation at 447 and 980 nm resulted in strong green emission (5F4, 5S2 → 5I8) from Ho3+. The effects of Yb3+ content and laser input power on emission intensity and luminescence decay were investigated in detail. Under excitation at 980 nm, the presence of Yb3+ increased emission intensity over the entire range, while the opposite behavior was observed under excitation at 447 nm. (Received May 3, 2019; Accepted July 10, 2019)

Effect of Yb3+ concentration on the green-yellow upconversion emission of SrGe4O9:Er3+ phosphors

Abstract This work presents the structural, morphological and luminescent, properties of SrGe4O9 (SGO):Er3+,Yb3+ phosphors. These phosphors were synthesized by simple combustion synthesis and subsequently annealed at 1100 °C. The XRD patterns revealed that all the SGO samples doped with Yb3+ concentrations from 2 to 10 at.% presented a trigonal pure phase (the Er3+ concentration was fixed to 1 at.%). The morphology of the SGO samples was analyzed by scanning electron microscopy and found that they are formed by microparticles with irregular shapes and average sizes in the range of 0.2 μm–3 μm. The luminescence measurements of the SGO:Er3+,Yb3+ samples showed the presence of two main emission bands at 551 nm (green) and at 662 nm (red) under excitation at 980 nm, which are associated to Er3+ transitions. For Yb concentration of 2 and 3 at.% the green band dominated, but the red band became more intense for Yb concentrations above 5 at.%. As result, the CIE coordinate changed from the green to the yellow region. The increase for the Yb content from 2 to 10 at.% also enhanced of the NIR emission of Er3+ ≈5 times and the maximum upconversion emission was observed for 8% of Yb concentration. Further, the surface of the SGO samples was analyzed by the FTIR technique in order to find OH groups which are common luminescent quenching centers, but these groups were not detected on the samples. Since the SGO samples presented tunable emission, absence of OH groups on their surface and stable crystalline structure for high Yb dopant concentrations, they could be good candidates as phosphors for solid state lighting or displays applications.

Contribution of energy transfer processes to excitation and relaxation of Yb3+ ions in Gd3(Al,Ga)5O12:RE3+, Yb3+ (RE3+ = Tm3+, Er3+, Ho3+, Pr3+)

Abstract Gd3(Al,Ga)5O12:RE3+, Yb3+ single crystals (RE3+ = Tm3+, Er3+, Ho3+, Pr3+) were fabricated by the Czochralski technique. Effect of Yb3+ concentration on spectral distribution of luminescence emitted by interacting RE3+-Yb3+ ion pairs and on the dynamics of excitation energy flow in systems under study was investigated and interpreted referring to previously reported spectroscopic features of Gd3(Al,Ga)5O12:RE3+ systems. It was concluded that observed quenching of the Yb3+ emission by co-doped rare earth ions results from an interplay between phenomena of quantum cutting, down shifting and energy dissipation by multiphonon emission.

Investigation of energy transfer in Pr3+, Yb3+ co-doped phosphate phosphor: The role of 3P0 and 1D2

The synthesis, crystal structure and photoluminescence and decay kinetics properties have been carried out for the Pr3+-Yb3+ co-doped YPO4 phosphors. Upon excitation with 447 nm, the intense emissions from 3P0, 1D2 and 1G4 excited states are all observed in the Pr3+ singly doped phosphors. The population of 1D2 state is attributed to cross-relaxation 3P0+3H4 → 1D2+3H6 and/or non-radiative multiphonon relaxation from 3P0 because of the larger maximum phonon energy of YPO4 host (1080 cm−1),which needs only 3–4 phonons to balance the energy gap between 3P0 and 1D2 excited states. For the Pr3+-Yb3+ codoped samples, the effect of Yb3+ concentration on the luminescence and decay kinetics of Pr3+ are investigated for the interpretation of observed experimental results. The observations and discussions manifest that the efficient energy transfer from Pr3+ to Yb3+ occurs, involving mainly 1D2 and 1G4 levels of Pr3+ ions instead of 3P0 level, which is not in accordance with many reported results. It is hoped that our results may give a new insights into the energy transfer mechanism in Pr3+-Yb3+ codoped system.

Study on Upconversion and Thermal Properties of Tm3+/Yb3+ Co-Doped La₂O₃-Nb₂O₅-Ta₂O₅ Glasses.

The effect of Yb3+ ions on upconversion luminescence and thermal properties of Tm3+/Yb3+ co-doped La2O3-Nb2O5-Ta2O5 glasses has been studied. Glass transition temperature is around 740 °C, indicating high thermal stability. The effect of Yb3+ ions on the thermal stability is not obvious. Both the glass forming ability and the upconversion luminescence first increase and then decrease with the increase of Yb3+ ions. The glasses perform low glass forming ability with ΔT around 55 °C. Blue and red emissions centered around 477, 651, and 706 nm are obtained at the excitation of 976 nm laser. The upconversion luminescence mechanism is energy transfer from Yb3+ to Tm3+ mixed with two- and three- photon processes. The thermal kinetic Differential Thermal Analysis (DTA)-analysis indicates that the average activation energy first increases and then decreases with the increase of Yb3+ ions. This result can be introduced in order to improve upconversion luminescence of glasses by crystallization in the future. Tm3+/Yb3+ co-doped La2O3-Nb2O5-Ta2O5 glasses with good upconversion and thermal properties show promising applications in solid-state laser, optical temperature sensing.

Upconversion luminescence properties of ZnO:Yb3+,Er3+ prepared by hydrothermal method

Ytterbium and erbium co-doped ZnO powders were prepared through simple and easy-controlled hydrothermal method. The phase, structure, morphology and surface elements of the obtained samples were characterized by X-ray diffraction, scanning electron microscopy (SEM), energy dispersive spectrometer, transmission electron microscope (TEM) and UV–Visible spectrophotometry. The performance of upconversion photoluminescence was investigated by fluorescence spectrophotometer. The ZnO:Yb3+,Er3+ powder samples generate red emission of 660 nm under the excitation wavelength 980 nm. The effect of Yb3+ doped concentration on the upconversion luminescence was studied. The results show that the optimal doped concentration is 20 mol%, and the back energy transfer will lead to fluorescence quenching when the concentration is increased again.

Effect of Yb3+ concentration and location on the thermally enhanced upconversion emission intensity of Yb/Ho: Na3ZrF7 nanocrystals

It was reported that the UC emission intensity can be improved by introducing a thermal field and this phenomenon is highly related to the Yb3+ ions. Herein, we verify the thermal-induced UC enhancement degree can be further increased by separating the Yb3+ ions in the core and shell to promote the population of the defect energy level and inhibit the back energy transfer from Ho3+ to Yb3+ ions.

Luminescence properties of LiYF4:Yb3+, Er3+ phosphors: A study on influence of synthesis temperature and dopant concentration

Yb3+ and Er3+ doped LiYF4:RE3+ (RE = Yb, Er) phosphors have been synthesized using solid state reaction of pre-converted rare earth fluorides and lithium fluoride. Structural and morphological properties of the synthesized fluoride phosphors are examined. Upconversion emission studies performed in the developed phosphors showed blue, green and red emission bands under 980 nm excitation. Effect of Yb3+ ions concentration and synthesis temperature on the upconversion emission bands has been investigated. As the synthesis temperature increased the phosphors exhibited intense upconversion luminescence. The colour co-ordinate analysis confirmed the strong green emission under upconversion process. Luminescence in synthesized phosphors have also been investigated with respect to 378 nm excitation. The prepared phosphors have shown good luminescent properties and could be a potential candidate for luminescent based device fabrications.

Influence of gamma radiation on enhancement of luminescent properties of GdPO4:Yb3+@SiO2 nanophosphors

The core/shell luminescent GdPO4:Yb3+@SiO2 nanophosphors have been synthesized via a facile solution combustion method. The effect of Yb3+ concentration and γ-radiation on the crystal phase, morphology and luminescent properties of nanophosphors has been studied. Upon photo excitation at 487 nm, GdPO4:Yb3+@SiO2 emits strong red luminescence at 640 nm and NIR luminescence at 731 nm corresponding to the 5F5 → 5I8 and 5F4 → 5I7 transitions, respectively. A 10-fold increase in luminescence intensity has been observed after increasing the Yb3+ content from 1% to 5%. Further, the Vis/NIR luminescence intensity of these nanophosphors had enhanced progressively 3–7 folds and 10–13 folds after exposed to 150 and 300 kGy γ-radiation, respectively. The dual advantage of Vis-NIR luminescence aided with biocompatibility makes these nanophosphors promising materials for biomedical applications.

Synthesis, structure and optical studies of ZnO:Eu3+,Er3+,Yb3+ thin films: Enhanced up-conversion emission

ZnO:Eu3+/Er3+/Yb3+thin films were deposited on Si (100) substrates using the sol–gel spin coating technique. The effect of Yb3+ concentration on the structure, particle morphology and optical properties of the films was examined. X-ray diffraction data showed that all the thin films crystallized in a hexagonal wurtzite structure of ZnO. The particle morphology and the distribution of atomic and molecular ionic species on the surface were investigated using scanning electron microscopy and time‐of‐flight secondary ion mass spectrometry, respectively. Atomic force microscopy was used to determine the surface roughness and particle sizes. Photoluminescence (PL) properties of the samples were measured using a mono-chromatized xenon lamp (conventional PL) and a 980 nm laser (up converted PL) as excitation sources. The conventional PL consisted of the normal defect emission. Yb3+ co-doping was found to improve the up converted (UC) PL intensity of both the RE3+ (Eu3+ and Er3+) ion emissions. This was ascribed to two possible energy transfer mechanisms from the 2F5/2 level of the Yb3+ ions to both the excited states of Er3+ and Eu3+ ions through Yb3+ → Er3+ & Er3+ → Eu3+ and Yb3+ → Eu3+ & Yb3+ → Er3+ on an individual behavior. The mechanism of energy transfer from Yb3+ to Eu3+ is explained by simplified energy level diagrams. The diagrams illustrate various defect levels and f-f transitions of the dopant ions. The emission colour was quantified by the standard international commission on illumination (CIE) chromaticity diagram.

Effect of Yb3+ concentration on tunable upconversion luminescence and optically temperature sensing behavior in Gd2TiO5:Yb3+/Er3+phosphors

The color-tunable upconversion (UC) emission and optical temperature sensing behavior was observed from the Er-Yb codoped Gd2TiO5 (GTO) phosphors synthesized by the simple sol-gel method. By control of the Yb3+ concentration, the phosphors are capable of generating color tunable UC luminescence from yellowish green to yellow, then to orange. The tunable emission is due to the energy back transfer from Er3+ to Yb3+ and the cross relaxation between the two neighboring Er3+ ions. The temperature dependence of the fluorescence intensity ratios (FIR) of two green UC emissions in Gd2TiO5:Yb3+/Er3+ phosphors with different Yb3+ doping concentration have been studied in the range of 298–573 K under 980 nm laser diode excitation and the maximum sensitivities were approximately 40.76 × 10−4 K−1 at 565 K. The above results suggest that the as-prepared Gd2TiO5:Yb3+/Er3+ phosphors have great potential for the applications of lightings and optical temperature sensors.

Effect of Yb3+ ions on structural and NIR emission of SrF2:Eu2+/Pr3+ down-conversion containing Na+ ions

The influence of Yb3+ ions on the structural and near infra-red (NIR) emission of the SrF2:Eu2+/Pr3+ down-conversion containing Na+ ions were investigated for solar cell applications. Most of the down-conversion studied materials for solar cell application are based on energy transfer from lanthanide ions to Yb3+ ions. For fluoride materials the charge compensation mechanism is of fundamental importance to maintain the electrical neutrality of the crystals. The x-ray diffraction data indicated that a mixture of cubic SrF2 and NaYbF4 phases gradually formed with increasing Yb3+ doping concentration. X-ray photoelectron spectroscopy (XPS) also confirmed the formation of the mixed fluoride structures. The F 1s peak showed two peaks that were assigned to SrF2 and NaYbF4. A negligible amount of Yb3+ ions that were converted into Yb2+ ions was also detected with XPS. From the photoluminescence data it was evident that the Na+ ions induced noticeable change to the NIR emission. This might reduce the quantum efficiency between the Pr3+ and Yb3+ ions in the system.

Change in thermoluminescence behaviour of cubic Gd2O3:Yb3+ phosphors with successive increase in Yb3+ ion concentrations

Nanocrystalline Yb3+ doped Gd2O3 phosphors were synthesized by solid state reaction method (SSRM), and effect of Yb3+ concentrations (1mol% to 7mol%) on thermoluminescence properties were studied. The XRD technique shows the cubic structure of prepared phosphor for different concentrations of Yb3+. No phase change was found due to the dopant concentration. The crystal size was calculated by Scherer's formula, which is found in 20–60nm range. The same was also confirmed from the field emission gun scanning electron microscopy (FEGSEM) image, which shows the formation of nanospheres having diameter 20–60nm range. They are found to be quite uniform in shapes and sizes. Functional group analysis was studied by Fourier transform infrared spectroscopy (FTIR) techniques and the elemental analysis of prepared phosphor was studied by energy dispersive X-ray spectroscopic (EDX) analysis. The samples were irradiated with UV and gamma radiation for the doses varying from 5 to 30min for UV and 0.5kGy to 2kGy for gamma respectively and their thermoluminescence (TL) characteristics have been studied. The effect of heating rate (3–7°Cs−1) and effect of Yb3+ concentration in TL glow curve have been studied. The TL glow curve of nanophosphor shows a peak at around 130°C for UV and at 247°C for gamma irradiation respectively. The TL response of the sample irradiated with different gamma doses shows a linear behaviour from 0.5kGy to 2kGy and become sublinear behaviour in the range of 5–25min UV exposure before it saturates with further increase in the dose. Simple glow curve structure, easy method of synthesis and the linear dose response make the nanocrystalline phosphor a good candidate for radiation dosimetry, especially for the estimation of high doses of gamma rays where the nanocrystalline phosphors generally saturated.

Effect of Yb3+ concentration on upconversion luminescence and temperature sensing behavior in Yb3+/Er3+ co-doped YNbO4 nanoparticles prepared via molten salt route

Yb3+/Er3+ co-doped YNbO4 nanoparticles (NPs) with an average size of 35nm were prepared via modified molten salt method for the first time. The phase purity, crystal structure, morphologies, and upconversion luminescence (UCL) properties as well as quantum yield and temperature sensing behavior of the as-prepared samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and upconversion luminescence (UCL) spectra, respectively. The XRD Rietveld refinements based on the XRD data were employed to reveal the phase purity and structure of the as-prepared samples. It was confirmed that the optimal doping concentration of Yb3+ ions in YNbO4:Yb3+, Er3+ NPs is around 10mol%, which has a maximal quantum yield of 0.1%. The temperature sensing behavior of the as-prepared YNbO4:Yb3+, Er3+ NPs was studied based on the fluorescent intensity ratio (FIR) technique from two thermal coupled 2H11/2 and 4S3/2 levels. It was found that the temperature sensitivity was sensitive to the doping concentration of Yb3+ ions. In addition, the dependence of UCL colors on temperature was observed and the corresponding mechanism was proposed. Therefore, the as-prepared Yb3+/Er3+ co-doped YNbO4 NPs have double function of optical thermometer and safety sign for the high temperature environment.

Up and Down Conversion Photoluminescence from Er, Yb and Li Doped Y2O3 Phosphors and Composites Films with PMMA

The synthesis of Y2O3: Er3+/Yb3+/Li+ phosphors by simple evaporation technique and it is incorporation into polymethyl methacrylate films by spin coating technique are reported. These phosphors exhibit luminescent properties when they are exited under continuous infrared light of 980 nm wavelength. The luminescence spectra show peaks for the green and red upconversion (UC) emissions and for the near infrared (1.534 μm) downconversion (DC) emission corresponding to inter electronic energy transitions of the Er3+ ions. The effect of Yb3+ and Li+ co-doping was found to change the light emission intensity up to 470 times in the case of UC emissions; while in the case of DC emission no effect is evident. Powders incorporated in polymeric films show similar emissions with high transparency in the visible (95%T in the Uv-Vis range).

The down-conversion and up-conversion photoluminescence properties of Na0.5Bi0.5TiO3:Yb3+/Pr3+ ceramics

Na0.5Bi0.5−x−yYbxPryTiO3 (NBT:xYb/yPr) ceramics with different Yb and Pr contents are prepared. Both the down-conversion (DC) and up-conversion (UC) photoluminescence (PL) of the ceramics via 453 and 980 nm excitation, respectively, are investigated. The effect of Yb3+ and Pr3+ doping contents on the DC and UC PL is significantly different from each other. Furthermore, the UC PL of the ceramics as a function of temperatures is measured to investigate the UC process in detail. Based on energy level diagram of Pr3+ and Yb3+ ions and the DC and UC PL spectra, the DC and UC PL mechanisms of Pr3+ and Yb3+ ions are discussed. Especially, the UC PL mechanism is clarified, which is different from the previously reported literature. Also, the temperature sensing properties of the ceramics are studied based on the photoluminescence ratio technique, using the thermal coupling energy levels of Pr3+.

Red–orange to green tunable upconversion emission from HfO2 ceramics embedded in polyester films

Up-conversion (UC) luminescence in hafnia powder (HfO2) doped with Er3+, Yb3+ and Li+ was studied under continuous wave excitation at 980nm. Powder samples were prepared by the simple evaporation technique and incorporated into polyester films (by spin coating technique). They were characterized using x-ray diffraction, electron microscopy, IR spectroscopy and UV–vis. A study of UC emission from Er3+ ions was performed including the analysis of the spectral and temporal behavior. The effect of Yb3+ co-doping concentration was found to change the intensity ratio of the Er3+ green and red characteristic emissions which allows for a color tuning of the UC emission. The mechanisms contributing to the UC luminescence are discussed as well.

The redistribution of charge density in CaF2:Yb3+

The fluorite type optical material Yb doped CaF2 was synthesized by the co-precipitation method. The synthesized materials with various Yb concentration were characterized by X-ray powder diffraction technique. The phase pure CaF2 was observed and the impurity doping effect was analyzed from the observed powder X-ray diffraction. The presence of Yb3+ in CaF2 materials was identified by energy dispersive X-ray analysis measurement and the morphological features were studied through scanning electron microscopy. The charge density distribution of Ca1−xYbxF2 (x = 0.00, 0.03, 0.06, 0.09 and 0.12) materials was analyzed using the maximum entropy method. The rearrangement of charge density distribution between Ca and F due to effect of Yb3+ impurity was analyzed.

Effect of Yb3+ concentration on upconversion luminescence of AlON:Er3+ phosphors

AlON:1.6 mol.%Er3+, x mol.%Yb3+ (x=0, 2.6, 3.1, 3.6, 4.1, 4.6) phosphors were synthesized successfully by aluminothermic reduction and nitridation (ATRN) method and characterized by X-ray diffraction (XRD), scanning electron microscopy (FESEM) and upconversion photoluminescence (UCPL) emission spectra. Under the excitation of diode laser 980 nm, the green (556 nm) and red (655 nm) upconverted emissions were observed, attributed to the 4S3/2→4I15/2 and 4F9/2→4I15/2 transition of Er3+ respectively. The emission intensity increased with increasing Yb3+ concentration due to the energy transfer (ET) between Yb3+ and Er3+. The upconverted emission reached the highest as x=3.6, and was pump-power dependent involving a two-photon process.