YVO4:Er3+/Yb3+纳米纤维的静电纺丝制备及表征

实验采用静电纺丝技术和高温煅烧法结合制备YVO_4∶Er~(3+)/Yb~(3+)纳米纤维,利用X-射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)对其物相结构、尺寸与形貌进行了基本的表征。并系统地研究了YVO_4∶Er~(3+)/Yb~(3+)纳米纤维的上转换发光性能。结果表明,YVO_4∶Er~(3+)/Yb~(3+)纳米纤维的红色发射与绿色发射,均随激光工作电流强度的增大而增大,都随着温度的升高呈现单调下降趋势。     

CaO对提高Er3+/Yb3+共掺ZrO2上转换发光效率的研究

采用固相反应法在1000℃烧结得到了Er3 +/Yb3共掺杂ZrO2-CaO粉末样品,样品在980 nm激发下发射较强的绿红光,发射光谱显示三个主要发射峰,中心波长依次为658nm、544 nm和530 nm,文中利用速率方程讨论了样品的上转换发光与抽运功率的关系,对绿红光的上转换发光途径进行了分析.通过XRD检测发现...     

基于Er3+/Yb3+掺杂的上转换玻璃陶瓷材料的制备和性能

采用熔融-晶化法在ZnO-Al2 O3-SiO2系玻璃陶瓷的基础上,用GeO2取代部分SiO2成功制备出Er3+/Yb3+共掺ZnO-Al2 O3-GeO2-SiO2系玻璃陶瓷,并通过对样品的硬度及上转换荧光测试分析确定了GeO2的最佳取代量为7.5wt％.研究发现在980 nm波长光的激发下,样品产生了绿色(524 nm、546 nm)和红色(659 nm)上转换发光,且当Er3+/Yb3+掺杂比为2.5:6.5时样品上转换荧光强度最强.     

LaF3:Ce3+荧光特性的研究

LaF3：Ce多晶中Ce^3 的荧光发射谱由双峰带结构组成。Ce^3 与其他稀土粒子共掺杂，Ce^3 发射强度均降低，原因是一部分稀土离子(如Eu^3 等)与Ce^3 产生了电子转移；一部分稀土离子(如Er^3 等)与Ce^3 产生了能量传递。     

BaWO4:Eu3+/Tb3+荧光粉的制备及其发光性能的研究

采用共沉淀法制备了Eu3+、Tb3+单掺或双掺的BaWO4荧光粉,探究了Eu3+的掺杂浓度、退火温度及Eu3+和Tb3+掺杂摩尔比对荧光粉发光性能的影响.实验结果表明,当反应温度为500℃、退火时间为2h、Eu3+掺杂浓度为5 mol％时,荧光粉发光强度最强.XRD结果表明,样品为立方晶系的BaWO4相.在掺杂Eu3+...     

Li~+掺杂对GdF_3:Ho~(3+)/Yb~(3+)纳米晶上转换发光影响的研究

本文采用水热法成功制取不同浓度的Gd F3:Ho3+/Yb3+纳米晶,并改变掺杂的Li+浓度、F源和EDTA-2Na量,研究其对上转换发光的影响。X射线衍射仪(XRD),傅立叶变换红外光谱(FT-IR),热重-差热分析仪(TG-DTA),场发射扫描电镜(FESEM)以及荧光分光光度计等对其结构和发光性能进行了表征。在980nm激发二极管激发下,发现位于520~560nm的绿光、630~670nm的红光两条可见光。结果证明,在其他条件一致情况下,Li+掺杂浓度为7.5mol%,EDTA-2Na为2mmol或NH4F为9mmol的发光效果最好。其中,Li+掺杂浓度为7.5mol%时,较未掺杂的绿、红光强度分别增强了5倍、2倍。     

Yb3+:Gd3Ga5O12激光晶体原料合成与生长的研究

采用溶胶-凝胶法合成了Yb：GGG多晶料.以XRD分析方法对合成料的前驱体及烧成的粉体的相结构进行了研究,XRD分析结果表明,950 ℃煅烧的粉体已是Yb:GGG纯相.采用提拉法,通过设计合理而稳定的温场、选择最佳工艺参数等生长了Yb:GGG晶体.荧光光谱测试结果表明,Yb:GGG晶体主要发射峰位于1030 nm,该荧光是由Yb3+激发态2F5/2向基态2F7/2能级跃迁产生的.     

β-NaYF4:Yb3+,Tm3+/g-C3N4复合水凝胶材料的制备及其应用

为了有效解决日益严重的水污染问题,本文研究了β-NaYF₄: Yb³⁺, Tm³⁺/g-C₃N₄复合材料的制备及其在可见光下催化降解亚甲基蓝模拟废水的最佳工艺条件。首先,利用溶剂热法合成了β-NaYF₄: Yb³⁺, Tm³⁺,再将煅烧法制备的 g-C₃N₄加入聚丙烯酸/聚乙烯醇水溶液,后滴入饱和硼酸溶液获得β-NaYF₄: Yb³⁺, Tm³⁺/g-C₃N₄/聚丙烯酸/聚乙烯醇复合水凝胶。利用X射线衍射仪、场发射扫描电子显微镜、紫外-可见分光光度计、热重分析仪、全自动比表面积微孔孔隙分析仪等进行表征;利用正交试验L₁₆(4⁵)考察复合材料的投加量、复合材料的比例、温度、亚甲基蓝溶液的pH、光照时间等因素,探索降解亚甲基蓝的最佳工艺条件。正交试验结果表明：光照时间为20.0h、pH为7.00、复合材料的投加量0.25g、温度20.0℃、复合材料活性组分β-NaYF₄: Yb³⁺, Tm³⁺与g-C₃N₄的比例为1∶4,此时对30.0mg/L亚甲基蓝降解率达到94.84%,循环降解亚甲基蓝模拟废水4次后的降解率仍高达为86.22%。     

纳米LaF3的介电性能

采用水溶液沉淀法制备了平均粒径17纳米的LaF3粉体,通过真空压结成形法制备了纳米LaF3块体,通过测量复阻抗谱研究了纳米LaF3块体材料的介电性能。     

Self-crystallized Ba2LaF7:Nd3+/Eu3+ glass ceramics for optical thermometry

Eu³⁺/Nd³⁺-codoped Ba₂LaF₇ transparent bulk glass ceramics were successfully fabricated by glass self-crystallization. The structure and morphology of the sample were investigated by X-ray diffraction, transmission electron microscopy (TEM), high-resolution TEM, and selected area electron diffraction. The fluorescence intensity ratios of Nd³⁺ emission at 800 nm to the Eu³⁺ emission at 699 nm (⁵D₀ → ⁷F₄) were measured under 578.3 nm laser excitation in a wide temperature range from 290 to 740 K. A relatively good temperature sensing performance was obtained with a maximum relative sensitivity of 1.02% K⁻¹ at 420 K. Both the emission peaks for temperature sensing were located in the optical window of biological tissue, which is favorable for biomedical applications. The results indicate that Ba₂LaF₇:Nd³⁺/Eu³⁺ glass ceramics have a potential application as temperature probes.     

Sc3+/Tm3+/Yb3+共掺六方NaYF4纳米粒子的上转换发光特性

稀土Tm3+和敏化剂(Yb3+)共掺NaYF4是目前发现的Tm3+上转换发光效率最高的材料,但还不能满足实际应用.实验中采用Sc3+/Tm3+/Yb3+共掺Na(Y1-x-y,Tmx,Yby)F4研究不同掺量Sc3+对Tm3+上转换发光效率的影响.用X射线多晶衍射仪和透射电子显微镜分析水热法合成样品的物相结构和晶粒尺寸...     

Upconverting luminescence based dual-modal temperature sensing for Yb3+/Er3+/Tm3+: YF3 nanocrystals embedded glass ceramic

Yb³⁺/Er³⁺/Tm³⁺ doped transparent glass ceramic containing orthorhombic YF₃ nanoparticles was successfully synthesized by a melt-quenching method. After glass crystallization, tremendously enhanced (about 5000 times) upconversion luminescence, obvious Start-splitting of emission bands as well as long upconversion lifetimes of Er³⁺/Tm³⁺ confirmed the incorporation of lanthanide activators into precipitated YF₃ crystalline environment with low phonon energy. Furthermore, temperature-dependent upconversion luminescence behaviors of glass ceramic were systematically investigated to explore its possible application as optical thermometric medium. Impressively, both fluorescence intensity ratio of Er³⁺: ²H_11/2 → ⁴I_15/2 transition to Er³⁺: ⁴S_3/2 → ⁴I_15/2 one and fluorescence intensity ratio of Tm³⁺: ³F_2,3 → ³H₆ transition to the combined Tm³⁺: ¹G₄ → ³F₄/Er³⁺: ⁴F_9/2 → ⁴I_15/2 ones were demonstrated to be applicable as temperature probes, enabling dual-modal temperature sensing. Finally, the thermal effect induced by the irradiation of 980 nm laser was found to be negligible in the glass ceramic sample, being beneficial to gain intense and precise probing signal and detect temperature accurately.     

Intense 2.85 μm mid-infrared emissions in Yb3+/Ho3+ codoped and Yb3+/Er3+/Ho3+ tridoped TBLL fluorotellurite glasses and their energy transfer mechanism

Yb³⁺/Ho³⁺ codoped and Yb³⁺/Er³⁺/Ho³⁺ tridoped TeO₂–BaF₂–LaF₃–La₂O₃ (TBLL) fluorotellurite glasses with low OH^? absorption (0.026 cm^-1), high glass transition temperature (434 °C) and low phonon energy (784 cm^-1) were prepared. Their mid-infrared fluorescence properties and related energy transfer (ET) mechanism were studied under 980 nm excitation. A strong emission at 2.85 μm was realized in Yb³⁺/Ho³⁺ codoped tellurite glass, which was attributed to the high-efficiency ET from Yb³⁺ ions to Ho³⁺, and the ET efficiency was 91.1%. Further introduction of Er³⁺ ions induced stronger 2.85 μm emission, and the ET efficiency was improved to 96.2%, ascribed to the establishment of more ET channels and Er³⁺ ions playing the role of ET bridge between Yb³⁺ and Ho³⁺ ions. These results indicate that the Yb³⁺/Er³⁺/Ho³⁺ tridoped tellurite glass could be a hopeful gain medium material for the ～3 μm fiber laser.     

Visible green upconversion luminescence of Er3+/Yb3+/Li+ co-doped CaWO4 particles

The upconversion (UC) luminescence of Li⁺/Er³⁺/Yb³⁺ co-doped CaWO₄ phosphors is investigated in detail. Single crystallized CaWO₄:Li⁺/Er³⁺/Yb³⁺ phosphor can be obtained, co-doped up to 25.0/5.0/20.0 mol% (Li⁺/Er³⁺/Yb³⁺) by solid-state reaction. Under 980 nm excitation, CaWO₄:Li⁺/Er³⁺/Yb³⁺ phosphor exhibited strong green UC emissions visible to the naked eye at 530 and 550 nm induced by the intra-4f transitions of Er³⁺ (²H_11/2,⁴S_3/2→⁴I_15/2). The optimum doping concentrations of Yb³⁺/Li⁺ for the highest UC luminescence were verified to be 10/15 mol%, and a possible UC mechanism that depends on the pumping power is discussed in detail.     

Tm~(3+)/Yb~(3+)共掺氟氧玻璃的光谱性质

制备了Tm3+/Yb3+共掺杂的20GaF3-15InF3-17CdF2-15ZnF2-10SnF2-3P2O5-(20-x-y)PbF2-xTmF3-yYbF3(x=0.2～2,y=1～4)系列玻璃。室温下,通过其吸收光谱,运用Judd-Ofelt理论计算了样品的强度参量Ωt(t=2,4,6)、自发辐射几率、荧光分支比和荧光寿命等光谱参数。研究发现,增加Tm3+掺入量对Ω2影响不大,Ω4、Ω6的值有增大的趋势。在980nm激发下的荧光光谱中,观察到5个上转换发射峰,其中发光较强的464nm的蓝光是三光子过程,650nm的红光和800nm的红外光是双光子过程,并讨论了其上转换发光机理和Tm3+、Yb3+掺杂浓度对发光强度的影响。     

Enhanced 2.0 μm Emission and Lowered Upconversion Emission in Fluorogermanate Glass‐Ceramic Containing LaF3:Ho3+/Yb3+ by Codoping Ce3+ Ions

Intense 2.0 μm emission of Ho³⁺ has been achieved through Yb³⁺ sensitization in fluorogermanate glass‐ceramic (GC) containing LaF₃ pumped with 980 nm laser diode (LD). The observation of concurrent emissions at 538, 650, and 1192 nm points to the additional deexcitation routes based on infrared‐to‐visible upconversion processes and Ho³⁺:⁵I₆ → ⁵I₈ radiative transition. Comparative investigations of photoluminescent spectra and decay curves have indicated the effective role of Ce³⁺ ions in enhancing the 2.0 μm fluorescence along with suppressing the occurrence of these concurrent emissions. This would offer a promising approach to develop compact and efficient 2.0‐μm laser systems.     

Effect of silica coating on the structural and luminescent properties of Sm3+/Yb3+ or Tm3+/Yb3+ co-doped TiO2 nanoparticles

The luminescent characteristics of spherical titanium dioxide (TiO₂) nanoparticles (NP's) doped with Sm³⁺/Yb³⁺ and Tm³⁺/Yb³⁺ with and without a silica coating were analyzed. These nanoparticles were synthesized using the spray pyrolysis technique and coated with silica through a wet chemical process. The Sm³⁺/Tm³⁺ and Yb³⁺ doping induces a triphasic poly-crystalline structure of rutile and anatase TiO₂ and a Sm₂Ti₂O₇/Tm₂Ti₂O₇ cubic phase. A Williamson-Hall analysis was used to monitor the tensions of the NP's crystallites at the various doping concentrations and with addition of the silica shell. The luminescent spectra presented the characteristic emission peaks for the electronic energy levels transitions of the Sm³⁺/Tm³⁺ and Yb³⁺ ions. The Sm³⁺/Yb³⁺ co-doped NP's showed a maximum emission peak in the visible region at 612 nm, associated with ⁴G_5/2 → ⁶H_7/2 transitions of the Sm³⁺ ions. The IR emission peak at 973 nm (²F_5/2 → ²F_7/2) pertaining to Yb³⁺. For the combination of Tm³⁺/Yb³⁺, two emissions associated with Tm³⁺ ions were observed at 440 nm (¹D₂ → ³F₄) and 806 nm (³H₄ → ³H₆). The emission at 973 nm (²F_5/2 → ²F_7/2) is correlated to the Yb³⁺ ions. Silica coating of the NP's resulted in luminescence emission intensity increase of about 4 times.     

BiLaWO6: Er3+/Tm3+/Yb3+ phosphor: Study of multiple fluorescence intensity ratiometric thermometry at cryogenic temperatures

Highly thermally stable Er³⁺/Tm³⁺/Yb³⁺ tri-doped bismuth lanthanum tungstate phosphors were prepared by high temperature solid-state reaction method. The structural and morphological properties of the prepared phosphors were analysed by X-ray diffraction (XRD), Raman spectroscopy and Scanning electron microscopy (SEM) coupled with energy dispersion spectrum (EDS). Visible upconversion (UC) luminescence was measured by exciting the phosphors with 980 nm laser radiation. The dependence of the UC intensity of each emission band of Er³⁺ and Tm³⁺ ions as a function of temperature in the range from 30 to 300 K was monitored. Fluorescence intensity ratios (FIR) of thermally coupled levels (TCL) and non-thermally coupled levels (NTCL) were analysed and verified with appropriate theoretical validation. The absolute (S_A) and relative sensitivities (S_R) were estimated and compared with the reported systems. In the present case of BiLaWO₆: Er³⁺/Tm³⁺/Yb³⁺, S_R (0.43 % K^?1) related to TCL of Er³⁺ UC is found to have maximum sensitivity compared to any of the NTCL combinations at 300 K. From this study we inferred that the S_R values estimated from NTCL are smaller than that of TCL involved in BLW: Er³⁺/Tm³⁺/Yb³⁺ phosphor. The temperature dependent CIE color coordinates were also evaluated in the cryogenic temperature region.