- 标题
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Improved negative thermal quenching effect via high sensitizer doping content in NaGdF4 based active-core/active-shell architecture
摘要： The strategies of introducing interior defects and reducing mean particle size have been applied to improve negative thermal quenching effect (TQE) in Yb3+ sensitized fluoride upconversion (UC) nanocrystals (NCs) recently. Herein, an active-core/active-shell structure with high total Yb3+ doping content is used to enhance the absorption intensity of Er3+ ions. Moreover, the Er3+ activators are doped into the shell to enable the energy migration process from activators to surface defects. In this scenario, with the rise of temperature, the suppression degree of this energy migration process is enlarged followed by an improved negative TQE. Specifically, with rising the temperature from 293 K to 413 K, the integral upconversion emission intensity of 40Yb: NaGdF4@60Yb/2Er: NaGdF4 NCs increases by ~ 8.24 times, while that of NaGdF4@20Yb/2Er: NaGdF4 NCs with a similar mean particle size only enhances ~ 3.44 times.
关键词： Yb3+ concentration,upconversion,temperature sensing,negative thermal quenching
更新于2025-11-14 17:03:37
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KMnF3:Yb3+,Er3+ Core-Active-Shell Nanoparticles with Broadband Down-Shifting Luminescence at 1.5 μm for Polymer-Based Waveguide Amplifiers
摘要： In this study, we prepared cubic-phase oleic-acid-coated KMnF3: Yb3+,Er3+ nanoparticles (NPs) and NaYF4:Yb3+,Er3+ NPs, which were about 23 nm. From the down-shifting emissions spectra of the two NPs obtained by 980 nm excitation, we observed the fact that the KMnF3: 18%Yb3+,1%Er3+ NPs were a luminescent material with a broadband near-infrared emission of 1.5 μm, and full-width at half-maximum (FWHM) of 55 cm?1, which was wider than that of the NaYF4: 18%Yb3+,1% NPs. Therefore, we believe that the oleic-acid-coated KMnF3:Yb3+,Er3+ NPs have great potential in fabricating broadband waveguide ampli?ers. Through epitaxial growth of a KMnF3: Yb3+ active-shell on the core NPs, we compounded KMnF3:Yb3+,Er3+@KMnF3:Yb3+ core-active-shell NPs whose 1.5-μm infrared emissions intensity was 3.4 times as strong as that of the core NPs. In addition, we manufactured waveguide ampli?ers using KMnF3:18%Yb3+,1%Er3+@KMnF3:2%Yb3+ NPs as the core materials of the waveguide ampli?ers. When the input signal power was 0.2 mW and the pump power was 200 mW, we achieved a relative gain of 0.6 dB at 1534 nm in a 10-mm long waveguide.
关键词： broadband,1.5 μm,KMnF3:Yb3+,Er3+ core-shell nanoparticles,polymer-based waveguide ampli?ers,down-shifting luminescence
更新于2025-11-14 15:27:09
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Large enhancement in upconverted green emission intensity from Ho3+/Yb3+ co-doped Y2Ti2O7 phosphor in the presence of Zn2+
摘要： The Ho3+, Yb3+ co-doped Y2Ti2O7 phosphor samples have been synthesized through solid state reaction method in the absence and presence of Zn2+ ions. The X-ray diffraction (XRD) analysis show that the phase of the crystal is face centered cubic. The zinc free phosphor shows weak upconversion emission in green region due to 5S2, 5F4 →5I8 transition of Ho3+ ion on excitation with 980 nm radiation. The emission intensity is enhanced significantly in the presence of Zn2+ ions due to increase in crystallinity, particle size and asymmetry in the crystal field. We are reporting ~92 times enhancement in the green emission intensity for 30 mol% co-doping of Zn2+ ions. The lifetime of 5S2 level of Ho3+ ion increases by increasing the concentration of Zn2+ ions. The intense green emission in this material may be suitable for display and other fluorescence based devices.
关键词： Upconversion,Y2Ti2O7 phosphor,Zn2+,Green emission,Ho3+ /Yb3+
更新于2025-11-14 14:48:53
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Near-infrared quantum cutting via energy transfer in Bi3+, Yb3+ co-doped Lu2GeO5 down-converting phosphor
摘要： In recent years, down-converting phosphors have grown rapidly and been still growing for their potential to significantly improve the photoelectric conversion efficiency of silicon-based solar cells. However, the discovery of new optical materials with optimized properties (in terms of emission intensity, chemical and thermal stability and quantum yield) would still be of the utmost importance. Herein, we report a novel down-converting phosphor Lu2GeO5: Bi3+, Yb3+. Our research results show that the energy transfer efficiency from Bi3+ to Yb3+ in Lu2GeO5 is as high as 65%. Via such an energy transfer from Bi3+ to Yb3+, an absorbed ultraviolet photon gives rise to almost two emitted infrared photons. The theoretical quantum yield of Lu2GeO5: Bi3+, Yb3+ system is calculated to reach up to 165%. The mechanism of the energy transfer from Bi3+ to Yb3+ is proved to be an electric dipole-dipole interaction. Meanwhile, Lu1.87GeO5: 0.03Bi3+, 0.10 Yb3+ phosphor exhibits an excellent resistance against thermal quenching. The present investigation provides people a new down-converting phosphor Bi3+, Yb3+ co-doped Lu2GeO5 with near-infrared quantum cutting to achieve high photoelectric conversion efficiency of silicon-based solar cells.
关键词： Lu2GeO5: Bi3+, Yb3+,Quantum cutting,Energy transfer,Down-converting phosphors
更新于2025-09-23 15:23:52
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Fabrication and up-conversion fluorescence property of Er<sup>3+</sup>/Yb<sup>3+</sup> co-doped Ca-Si-Ti biomaterials
摘要： This work demonstrates bulk-type up-conversion biomaterials which could be used as a bone repair material with the ability to monitor bone mineralization. Er3+/Yb3+ co-doped Ca-Si-Ti (CST3: TiO2 content is 30 mol%) bulk biomaterials were prepared via containerless processing technique in an aerodynamic levitation furnace and with subsequently heat treatment. The up-conversion fluorescence property was influenced by Yb3+ doping concentration, heat-treatment and mineralization in simulated body fluid (SBF). Optimum emission intensities were obtained for the sample with 20 mol% of Yb3+ doping concentration and heat treatment at 937 °C for 2 h. Hydroxyapatite (HAP) deposition was observed on the surface of the samples after soaking in SBF for 14 days, and the up-conversion fluorescence intensity of the samples decreased with the increase of soaking time. This indicates that Er3+/Yb3+ co-doped CST3 materials are bioactive, in which the HAP mineralization in bone repair could be monitored by measuring the intensity change of up-conversion fluorescence.
关键词： Heat treatment,Up-conversion fluorescence,Containerless processing,Mineralization,Er3+/Yb3+ co-doped Ca-Si-Ti biomaterial
更新于2025-09-23 15:23:52
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Photoluminescence properties of Er3+/Yb3+ doped ZrO2 coatings formed by plasma electrolytic oxidation
摘要： In the present work, down- and up-conversion photoluminescence properties of Er3+/Yb3+ doped ZrO2 coatings formed by plasma electrolytic oxidation of zirconium in electrolyte containing Er2O3 and Yb2O3 particles were investigated. Down-conversion PL analysis shows that emission spectra of ZrO2:Er3+/Yb3+ coatings excited with 280 nm radiation are composed of broad PL band related to ZrO2 host and bands assigned to f-f transitions of Er3+. The main PL emission bands of Er3+ at around 548 nm and 560 nm are related to 4S3/2→4I15/2 transition. PL excitation spectra monitored at 548 nm feature broad band in the region from 250 nm to 350 nm which is associated with the electron transfer transition from 2p orbital of O2? to 4f orbital of Er3+ and transitions of ZrO2. On the other hand, bands in PL excitation spectra ranging from 350 nm to 535 nm are related to 4f transitions of the Er3+ from the ground state 4I15/2 to higher energy levels. Down-conversion PL intensity decreases with increasing concentration of Yb3+ in coating due to energy transfer from Er3+ to Yb3+. ZrO2:Er3+/Yb3+ coatings show intense green (4S3/2→4I15/2) and red (4F9/2→4I15/2) up-conversion PL emission under the excitation with a 980 nm diode laser. With increasing Yb3+ concentration red up-conversion PL intensity increases more rapidly with respect to green emission, because red up-conversion PL intensity strongly depends on Yb3+ concentration, i.e. 4F9/2 state of Er3+ is directly excited by energy transfer from excited Yb3+.
关键词： up-conversion,Photoluminescence,Er3+/Yb3+,Down-conversion,Plasma electrolytic oxidation
更新于2025-09-23 15:23:52
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Optical, structural and luminescence properties of oxyfluoride phosphate glasses and glass-ceramics doped with Yb3+
摘要： The impact of Al2O3 and Y2O3 addition on the structure, Yb3+ luminescence and crystallization is investigated for glasses in the P2O5-SrO-Na2O system. Although the addition of Al2O3 and Y2O3 leads to a more connected phosphate network as evidenced using IR and Raman spectroscopies and increases the glass transition temperature, it does not affect strongly the site of the Yb3+. The addition of Al2O3 and Y2O slightly decreases the rate of the glass crystallization. Surface crystallization occurs upon heat treatment. Crystallization was confirmed by the presence of sharp peaks in the XRD patterns of the glasses. Independently of the glass composition, multiple different crystalline phases precipitate in the glasses upon heat treatment. The precipitation of the Na1O7P2Yb1 crystal phase leads to an increase of the excited state 2F5/2 lifetime of Yb3+ and also of the bandwidth of the Yb3+ emission band centered at 1μm.
关键词： nucleation and growth,Yb3+ doped phosphate glasses,Raman & Infrared spectroscopies,Yb3+ luminescence properties,heat treatment
更新于2025-09-23 15:22:29
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Apparent self-heating of individual upconverting nanoparticle thermometers
摘要： Individual luminescent nanoparticles enable thermometry with sub-diffraction limited spatial resolution, but potential self-heating effects from high single-particle excitation intensities remain largely uninvestigated because thermal models predict negligible self-heating. Here, we report that the common “ratiometric” thermometry signal of individual NaYF4:Yb3+,Er3+ nanoparticles unexpectedly increases with excitation intensity, implying a temperature rise over 50 K if interpreted as thermal. Luminescence lifetime thermometry, which we demonstrate for the first time using individual NaYF4:Yb3+,Er3+ nanoparticles, indicates a similar temperature rise. To resolve this apparent contradiction between model and experiment, we systematically vary the nanoparticle’s thermal environment: the substrate thermal conductivity, nanoparticle-substrate contact resistance, and nanoparticle size. The apparent self-heating remains unchanged, demonstrating that this effect is an artifact, not a real temperature rise. Using rate equation modeling, we show that this artifact results from increased radiative and non-radiative relaxation from higher-lying Er3+ energy levels. This study has important implications for single-particle thermometry.
关键词： upconverting nanoparticles,NaYF4:Yb3+,Er3+,thermometry,luminescence,self-heating
更新于2025-09-23 15:21:21
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The effect of Yb3+ ion substitution on dielectric and microstructural properties of Y3Al5O12 ceramics
摘要： The electrical and dielectric properties of Y3Al5O12 (yttrium aluminum garnet, YAG) ceramics are investigated in detail. YAG:(Yb)x (0.01 ≤ x ≤ 0.09) was synthesized by a solid state reaction and characterized by X-ray powder diffraction, field emission scanning electron microscopy, and high-resolution transmission electron microscopy. The electrical and dielectric properties have been intensively studied under certain bias voltages up to a frequency of 10 MHz. These properties are dependent on the substitution rates, independent of the bias voltages. The experimental result shows that Yb3+ ion substitution into YAG ceramics significantly influences the conductivity, dielectric constant, and lossy mechanisms, which is probably owing to the 3d-Al ions and 4f-Yb ions incorporated at different positions of structural symmetries in Y3?xYbxAl5O12 (0.00 ≤ x ≤ 0.09) ceramics.
关键词： ceramics,Yb3+ ion substitution,Y3Al5O12,dielectric properties,microstructural properties
更新于2025-09-23 15:21:01
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Microwave Sol-Gel Derived PbY2(MoO4)4:Er3+/Yb3+ Double Molybdate and Their Up-Converted Optical Properties
摘要： PbY2-x(MoO4)4:Er3+/Yb3+ double molybdate phosphors with the correct doped concentrations of Er3+ and Yb3+ (x = Er3+ + Yb3+, Er3+ = 0, 0.05, 0.1, 0.2 and Yb3+= 0, 0.2, 0.45) were precisely prepared using the sol-gel method assisted by the microwave technique; their up-converted optical properties were studied. The particles showed well-crystallized morphology after heat-treated at 900 °C for 16 h. They had a homogeneous and fine morphology with grain sizes of 2-5 μm. After excitation at 980 nm, the PbY1.7(MoO4)4:Er0.1/Yb0.2 and PbY1.5(MoO4)4:Er0.05/Yb0.45 double molybdates provided a strong up-converted emission band of 525 nm, a weak up-converted emission band of 550 nm in the green region and a very weak up-converted emission band of 655 nm in the red region. The spectroscopic spectra of Raman for the doped molybdates showed the presence of strong peaks at higher and lower frequencies. It was induced by highly modulated structures of PbY2-x(MoO4)4 by the incorporation of the Er3+ and Yb3+ ions into the crystal lattice. These results were attributed to the unit cell shrinkage as well as the anion deficient of the MoO4-x group.
关键词： PbY2-x(MoO4)4:Er3+/Yb3+,Sol-gel,Up-converted photoluminescence,Raman spectroscopy,Microwave
更新于2025-09-23 15:21:01