Er3+/Yb3+掺杂氟硅铅酸盐微晶玻璃的上转换发光

制备了微晶体尺寸大约在10—12 nm范围内的Er³⁺,Yb³⁺共掺杂透明氟硅铅酸盐微晶玻璃.相同功率激发下,纳米微晶玻璃中Er³⁺离子的²H_11/2,⁴S_3/2→⁴I_15/2的绿色上转换荧光和⁴F_9/2→关键词： 3+')" href="#">Er³⁺ 3+')" href="#">Yb³⁺ 能量传递 纳米微晶玻璃     

Infrared and visible emission of Er in combustion-synthesized CaAl2O4 phosphors

New near-infrared luminescent, monoclinic CaAl₂O₄:Er³⁺ phosphor was prepared by using the combustion route at furnace temperatures as low as 500 °C in a few minutes. Combustion synthesized phosphor has been well characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive analysis of X-ray (EDAX) mapping studies. The luminescence spectra of Er³⁺-doped calcium aluminate were studied at UV (380 nm), vis (488 nm) and IR (980 nm) excitation. Upon UV and vis excitation, the CaAl₂O₄:Er³⁺ phosphor exhibits emission bands at ~523 nm and at ~547 nm, corresponding to transitions from the ²H_11/2 and ⁴S_3/2 erbium levels to the ⁴I_15/2 ground state. A strong luminescence at 1.55 μm in the infrared (IR) region due to ⁴I_13/2→⁴I_15/2 transition has been observed in CaAl₂O₄:Er³⁺ phosphor upon 980 nm CW pumping. In the spectrum of IR-excited up-conversion luminescence, green (~523 and ~547 nm) and red (662 nm) luminescence bands were present, the latter associated with the ⁴F_9/2→⁴I_15/2 transitions of Er³⁺ ions. Both excited state absorption and energy transfer may be proposed as processes responsible for the population of the ⁴S_3/2 and ⁴F_9/2 erbium levels upon IR excitation. The mechanisms responsible for the up-conversion luminescence are discussed.     

Effects of Ce on the spectroscopic properties of transparent phosphate glass ceramics co-doped with Er/Yb

We have prepared Er³⁺/Yb³⁺ co-doped transparent phosphate glass ceramics by the high-temperature melting technique, and demonstrated the influence of energy acceptors Ce³⁺ ions on the up-conversion and 1.54 μm emission properties of Er³⁺. The energy transfer mechanism is discussed based on the energy matching and the energy level structure. The phonon-assisted energy transfer between Er³⁺ and Ce³⁺ favors population feeding from the ⁴I_11/2 to the ⁴I_13/2 level, and therefore drastically decreases the up-conversion emission intensity of Er³⁺. Meanwhile, 1.54 μm fluorescence enhances greatly with the introduction of Ce³⁺ ions at the proper concentration.     

Erbium-doped lead silicate glass for near-infrared emission and temperature-dependent up-conversion applications

Erbium-doped lead silicate glass has been investigated for near-infrared emission and up-conversion applications. Near-infrared emission due to ⁴I_13/2 → ⁴I_15/2 transition of Er³⁺ is relatively broad (70.5 nm) and long-lived (3.7 ms). Also, up-conversion luminescence spectra of Er³⁺ ions in lead silicate glass have been examined as a function of temperature. The relative intensities of luminescence bands corresponding to ²H_11/2 → ⁴I_15/2 and ⁴S_3/2 → ⁴I_15/2 transitions of Er³⁺ were determined with temperature. The fluorescence intensity ratio and temperature sensitivity were calculated. The maximum sensitivity for Er³⁺ doped lead silicate glass is close to 26.4 × 10^?4 K^?1 at T = 590 K.     

The effect of Y co-doping on the persistent up-conversion luminescence of the ZrO2:Yb,Er nanomaterials

The effect of the defects due to the charge compensation obtained with the yttrium co-doping to the ZrO₂:Yb³⁺,Er³⁺ up-converting phosphors was studied. The materials were prepared with the combustion method. The materials purity was analyzed with the FT-IR spectroscopy. The crystal structure was studied with the X-ray powder diffraction and the crystallite sizes were estimated with the Scherrer formula. Up-conversion luminescence was excited at room temperature with an IR-laser at 970 nm. The up-conversion luminescence spectra showed red (650-685 nm) and green emission (520-560 nm) due to the ⁴F_9/2→⁴I_15/2 and (²H_11/2,⁴S_3/2)→⁴I_15/2 transitions of Er³⁺, respectively. Persistent up-conversion luminescence was observed both in the Yb³⁺,Er³⁺ and Y³⁺,Yb³⁺,Er³⁺ doped materials.     

Spectroscopic properties of new luminescent system based on vanadate(V) crystal doped with erbium ions

Er³⁺-doped KCaY(VO₄)₂ microcrystalline samples were synthesized using a high temperature solid-state reaction technique. Spectroscopic properties of Er³⁺: KCaY(VO₄)₂ are studied and the nature of emissions is discussed. A strong green and infrared luminescence were observed under excitation at 314 nm in the O²⁻→V⁵⁺ charge-transfer transitions and direct excitation of Er³⁺ ions at 435 nm. A strong emission lines in the blue region are due to the transitions of VO₄³⁻ ions have been observed at 77 K. The Judd-Ofelt parametrization scheme has been applied to the analysis of the room temperature absorption spectra in order to evaluate the intensity parameters, the branching ratios and the radiative lifetimes of the ⁴I_13/2, ⁴I_11/2, ⁴F_9/2 and ⁴S_3/2 emitting levels. The effective cross-section has been calculated for the ⁴I_13/2→⁴I_15/2 transition, indicating that the title compounds is a promising active medium for application in the three-level laser system. The up-conversion emission in Er³⁺: KCaY(VO₄)₂ was investigated at 300 K. The decay profiles of the Stokes and anti-Stokes emissions were measured and the mechanism of up-conversion luminescence is discussed.     

Improvement of thermal and spectroscopic behavior of Er<Superscript>3+</Superscript>/Ce<Superscript>3+</Superscript> co-doped tellurite glass for lasing materials

Tellurite glasses (TeO₂–ZnO–Nb₂O₅) mono-doped Er³⁺ and co-doped Er³⁺/Ce³⁺ have been prepared using the melt-quenching technique. To evaluate the effect of Ce³⁺ on the structural, thermal stability of glass hosts and fluorescence properties of Er³⁺, X-ray diffraction patterns, Ftir spectra, differential scanning calorimeter curves, absorption spectra, fluorescence emission spectra, fluorescence lifetimes, up-conversion emission spectra of glass samples were measured and investigated. Using Judd–Ofelt theory, we calculated intensity parameters (Ω₂, Ω₄ and Ω₆), spontaneous emission probabilities, the radiative lifetime, luminescence branching factors and the quantum yield of luminescence for ⁴I_13/2 → ⁴I_15/2 transition. The co-doping with Ce³⁺ was effective on the suppression of up-conversion emission of Er³⁺ owing to the phonon-assisted energy transfer: Er³⁺:⁴I_11/2 + Ce³⁺:²F_5/2 → Er³⁺:⁴I_13/2 + Ce³⁺:²F_7/2 which contributed the effective enhancement of 1.53 µm fluorescence emission. The change in optical properties with the addition of Ce³⁺ ions have been discussed and compared with other glasses. Using the Mc Cumber method for the ⁴I_13/2 → ⁴I_15/2 transition, absorption cross-section, calculated emission cross-section, and gain cross-section values support that TZNEr1Ce1 glass is a potential material for developing broad-band and high-gain erbium-doped fiber amplifiers applied for 1.53 µm.     

Up-conversion luminescence of Er/Yb/Nd-codoped tellurite glasses

Up-conversion luminescence and energy transfer (ET) processes in Nd³⁺-Yb³⁺-Er³⁺ triply doped TeO₂-ZnO-Na₂O glasses have been studied under 800 nm excitation. Intense green up-conversion emissions around 549 nm, which can be attributed to the Er³⁺: ⁴S_3/2→⁴I_15/2 transition, are observed in triply doped samples. In contrast, the green emissions are hardly observed in Er³⁺ singly doped and Er³⁺-Yb³⁺ codoped samples under the same condition. Up-conversion luminescence intensity exhibits dependence of Yb₂O₃-concentration and Nd₂O₃-concentration. Up-conversion mechanism in the triply doped glasses under 800 nm pump is discussed by analyzing the ET among Nd³⁺, Yb³⁺ and Er³⁺. And a possible up-conversion mechanism based on sequential ET from Nd³⁺ to Er³⁺ through Yb³⁺ is proposed for green and red up-conversion emission processes.     

Er3+-doped sol–gel SnO2 for optical laser and amplifier applications

Erbium-doped tin dioxide (SnO₂:Er³⁺) was obtained by the sol–gel method. Spectroscopic properties of the SnO₂:Er³⁺ are analyzed from the Judd–Ofelt (JO) theory. The JO model has been applied to absorption intensities of Er³⁺ (4f¹¹) transitions to establish the so-called Judd–Ofelt intensity parameters: Ω₂, Ω₄, and Ω₆. With the weak spectroscopic quality factors Ω₄/Ω₆, we expect a relatively prominent infrared laser emission. The intensity parameters are used to determine the spontaneous emission probabilities of some relevant transitions, the branching ratios, and the radiative lifetimes of several excited states of Er³⁺. The emission cross section (1.31×10^-20 cm²) is evaluated at 1.54 μm and was found to be relatively high compared to that of erbium in other systems. Efficient green and red up-conversion luminescence were observed, at room temperature, using a 798-nm excitation wavelength. The green up-conversion emission is mainly due to the excited state absorption from ⁴ I _11/2, which populates the ⁴ F _3/2,5/2 states. The red up-conversion emission is due to the energy transfer process described by Er³⁺ (⁴I_13/2)+Er³⁺(⁴I_11/2)→Er³⁺(⁴F_9/2)+Er³⁺ (⁴ I _15/2) and the cross-relaxation process. The efficient visible up-conversion and infrared luminescence indicate that Er³⁺-doped sol–gel SnO₂ is a promising laser and amplifier material. PACS 71.20.Eh; 74.25.Gz; 78.55.-m     

Defect Structure and Up-conversion Luminescence Properties of ZrO<Subscript>2</Subscript>:Yb<Superscript>3+</Superscript>,Er<Superscript>3+</Superscript> Nanomaterials

The up-converting ZrO₂:Yb³⁺,Er³⁺ nanomaterials were prepared with the combustion and sol–gel methods. FT-IR spectroscopy was used for analyzing the impurities. The crystal structures were characterized with X-ray powder diffraction and the mean crystallite sizes were estimated with the Scherrer formula. Up-conversion luminescence measurements were made at room temperature with IR-laser excitation at 977 nm. The IR spectra revealed the conventional and OH⁻ impurities for the combustion synthesis products. The structure of the ZrO₂:Yb³⁺, Er³⁺ nanomaterials was cubic except for the minor monoclinic and tetragonal impurities obtained with the sol–gel method. The materials showed red (650–700 nm) and green (520–560 nm) up-conversion luminescence due to the ⁴F_9/2→⁴I_15/2 and (²H_11/2, ⁴S_3/2)→⁴I_15/2 transitions of Er³⁺, respectively. The products obtained with the combustion synthesis exhibited the most intense luminescence intensity and showed considerable afterglow.     

Effect of heat treatment on the structural and optical properties of tellurite glasses doped erbium

The 75TeO₂–20ZnO–4Na₂CO₃–1Er₂O₃ (in molar ratio) glass system was prepared by the conventional melt-quenching method. As such, the samples prepared were investigated by differential scanning calorimetry (DSC), X-ray diffractrometry (XRD), Raman spectroscopy and infrared luminescence. DSC analyses were carried out on our glass at different heating rates between 5 and 20 °C/min. The result of the annealing temperature on the spectroscopic properties of Er³⁺ in tellurite glasses was discussed. The activation energy, for surface crystallization, was determined graphically from a Kissinger-type plot and had a value about 897.2 kJ/mol. Crystalline phases for both α-TeO₂, γ-TeO₂ and Zn₂Te₃O₈ system were determined by the XRD method and were confirmed by Raman spectroscopy characterizations after heat treatment. The effect of heat treatment on absorption spectra and luminescence properties in the tellurite glass was also investigated. With heat treatment, the ultraviolet absorption edge presented a redshift. As a result, the Judd–Ofelt (J–O) intensity parameters (Ω₂, Ω₄, Ω₆) were determined. The spontaneous emission probabilities of some relevant transitions, the branching ratio and the radiative lifetimes of several excited states of Er³⁺ were predicted using intensity J–O parameters. The near infrared emission that corresponds to Er³⁺: ⁴I_13/2→⁴I_15/2 can be significantly enhanced after heat treatment. Notably, it is found that the luminescence lifetime in the present system is much longer than that in most other glasses and glass ceramics. A comparative study on luminescence performance suggests that the obtained glass ceramic is a promising material for Er³⁺ doped fiber amplifiers.     

Er3+及Er3+/Yb3+掺杂ZrO2-Al2O3的制备及发光性质

采用共沉淀法制备了纳米晶ZrO₂-Al₂O₃∶Er³⁺发光粉体.所制备的粉体室温下具有Er3+离子特征荧光发射,主发射在绿光,其中位于547 nm、560 nm的绿光最强,并得出稀土离子与基质之间有能量传递.对不同煅烧温度下的样品研究表明:因不同温度下所制得的样品晶相不同.研究了纳米晶ZrO2-Al2O3∶Er3+及ZrO₂-Al₂O₃∶Er³⁺/Yb³⁺的上转换发光,并分析了上转换的跃迁机制.发现ZrO₂-Al₂O₃∶Er³⁺的绿光为双光子过程,而ZrO₂-Al₂O₃∶Er³⁺、Yb³⁺的上转换光谱中,红光和绿光也为双光子过程,而极弱的蓝光为三光子过程.讨论了Er³⁺的浓度猝灭现象.最适宜掺杂浓度的原子分数为2%（Er³⁺/Zr⁴⁺）.     

Structural and Upconversion Studies of Er3+ Codoped with CdS Nanoparticles in Sol-Gel Glasses

The Er³⁺ codoped with CdS nanoparticles in sol-gel glass with an average particle size of about 10 nm have been synthesized by sol-gel method. The green and red up-conversion emissions centered at about 534, 560 and 680 nm, corresponding to the ²H_11/2→⁴I_15/2, ⁴S_3/2→⁴I_15/2 and ⁴F_9/2→⁴I_15/2 transitions of Er³⁺, respectively; were detected by a 800 nm excitation. The two-photon absorption process is involved in the green and red up-conversion emissions.     

Er,Yb:YAG微晶玻璃发光特性的研究

高温熔制Er³⁺，Yb³⁺离子掺杂CaO-Y₂O₃-Al₂O₃-SiO₂系统玻璃，并进行微晶化处理，研究了微晶玻璃中Er³⁺离子的发光及上转换发光特性，分析了微晶玻璃上转换发光机理.结果表明：原始玻璃经热处理得到了Er,Yb:YAG微晶玻璃，微晶玻璃中Er³⁺离子在室温下⁴I_13/2→⁴I_15/2跃迁产生横盖1450—1650nm区间的超宽带荧光，荧光半高宽达180nm，这可能由于YAG微晶相中Er³⁺离子与玻璃相中残留Er³⁺离子的共同发光；Er³⁺与Yb³⁺离子局域基质声子能量的降低使微晶玻璃Er³⁺离子上转换发光强度与原始玻璃相比显著提高，绿光、红光上转换荧光强度比玻璃样品分别增强约7和3倍；微晶化后Er³⁺，Yb³⁺离子局域环境发生变化也导致微晶玻璃中Er³⁺离子绿光、红光上转换发光相对强度发生变化. 关键词： 铒 镱:钇铝石榴石 微晶玻璃 荧光光谱     

Avidin conjugation to up-conversion phosphor NaYF4:Yb3+, Er3+ by the oxidation of the oligosaccharide chains

NaYF₄:Yb³⁺, Er³⁺ nanoparticles were successfully prepared by a polyol process using diethyleneglycol (DEG) as solvent. After being functionalized with SiO₂–NH₂ layer, these NaYF₄:Yb³⁺, Er³⁺ nanoparticles can conjugate with activated avidin molecules (activated by the oxidation of the oligosaccharide chain). The as-formed NaYF₄:Yb³⁺, Er³⁺ nanoparticles, NaYF₄:Yb³⁺, Er³⁺ nanoparticles functionalized with amino groups, avidin conjugated amino-functionalized NaYF₄:Yb³⁺, Er³⁺ nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), atomic force microscopy (AFM), Fourier transform infrared (FT-IR), UV/Vis absorption spectra, and up-conversion luminescence spectra, respectively. The biofunctionalization of the NaYF₄:Yb³⁺, Er³⁺ nanoparticles has less effect on their luminescence properties, i.e., they still show the up-conversion emission (from Er³⁺, with ⁴S_3/2 → ⁴I_15/2 at ~540 nm and ⁴F_9/2 → ⁴I_15/2 at ~653 nm), indicative of the great potential for these NaYF₄:Yb³⁺, Er³⁺ nanoparticles to be used as fluorescence probes for biological system.     

Synthesis and luminescence properties of Gd6MoO12:Yb3+, Er3+ phosphor with enhanced photoluminescence by Li+ doping

Yb³⁺/Er³⁺ co-doped Gd₆MoO₁₂ and Yb³⁺/Er³⁺/Li⁺ tri-doped Gd₆MoO₁₂ phosphors were prepared by adjusting the annealing temperature via the high temperature solid-state method. Under the excitation of 980 nm semiconductor, the upconversion luminescence properties were investigated and discussed. In the experimental process, we get the optimum Yb³⁺ concentration and the concentration quench effect will happen while the concentration extends the given region. According to the Yb³⁺ concentration quenching effects, the critical distance between Yb³⁺ ions had been calculated. The measured UC luminescence exhibited a strong red emission near 660 nm and green emission at 530 nm and 550 nm, which are due to the transitions of Er³⁺(⁴F_9/2, ²H_11/2, ⁴S_3/2) → Er³⁺(⁴I_15/2). Then the effect of excitation power density in different regions on the upconversion mechanisms was investigated and the calculated results demonstrate that the green and red upconversion is a two-photon process. A possible mechanism was discussed. After Li⁺ ions mixing, the upconversion emission enhanced largely, and the optimum Li⁺ concentration was obtained while fixed the Yb³⁺ and Er³⁺ on the above optimum concentration. This enhancement owns to the decrease of the local symmetry around Er³⁺ after Li⁺ ions doping into the system. This result indicates that Li⁺ is a promising candidate for improving luminescence in some case.     

Enhancement of upconversion luminescence in Tm/Er/Yb-codoped glass ceramic containing LiYF4 nanocrystals

A transparent Er³⁺–Tm³⁺–Yb³⁺ tri-doped oxyfluoride glass ceramics containing LiYF₄ nanocrystals were prepared. Under 980 nm laser diode (LD) pumping, intensive red, green and blue upconversion (UC) was obtained. The blue, green, and red UC radiations correspond to the transitions ¹G₄→³H₆ of Tm³⁺, ²H_11/2/⁴S_3/2→⁴I_15/2, and ⁴F_9/2→⁴I_15/2 of Er³⁺ ions, respectively. This is similar to that in Tm³⁺–Yb³⁺ and/or Er³⁺–Yb³⁺ co-doped glass ceramics. However, the blue UC radiations of the Er³⁺–Yb³⁺ co-doped glass ceramics is two-photon process due to cooperative energy transfer. The UC mechanisms were proposed based on spectral, kinetic, and pump power dependence analyses.     

Intense Upconversion Luminescence of Yb<Superscript>3+</Superscript>-Er<Superscript>3+</Superscript> in Li<Subscript>2</Subscript>O Content Tungsten-tellurite Glasses

The Er³⁺ -Yb³⁺ codoped in Li₂O content tungsten -tellurite (TWL) transparent glasses are synthesized and measured the absorption, Raman and upconversion luminescence (UPL) spectra. At room temperature intense green emission peak at 560 nm ( ⁴S_3/2→⁴I_15/2) and red emission peak at 670 nm ( ⁴F_9/2→⁴I_15/2) of Er³⁺ observed even at minimum 86 mW pumping power of infrared 980 nm excitation. For structure of the TWL glass, Raman spectrum result revealed that an important role of WO₃ in the formation of glass network linkage with Li₂O. Under this influence estimated lifetime of the ⁴I_11/2 of Er³⁺ was 1.89 μs and due to lower phonon energy of the glass produce strong upconversion signal. The effect of Er₂O₃ concentration on emission intensity result indicated that green emission intensity initially increase in compare to red emission. Under the 980 nm pump power variation measured the relatively increases the red emission to the green emission intensity and analyze the possible upconversion mechanism and process.     

Comparative Investigation on Nanocrystal Structure and Luminescence Properties of Gadolinium Molybdates Codoped with Er<Superscript>3+</Superscript>/Yb<Superscript>3+</Superscript>

This paper reports on the comparative investigation of nanocrystal structure and luminescence properties of Er³⁺/Yb³⁺-codoped gadolinium molybdate nanocrystals Gd₂(MoO₄)₃ and Gd₂MoO₆ synthesized by the Pechini method with citric acid and ethylene glycol. Their crystallization, structure transformation, and morphologies have been investigated by X-ray diffraction, thermogravimetric/differential scanning calorimetry, and transmission electron microscopy. It is noticed that Er³⁺/Yb³⁺-codoped monoclinic Gd₂(MoO₄)₃ nanocrystals have shown an intense upconversion through a sintering of the organic complex precursor at 600°C. Furthermore, it transforms to orthorhombic Gd₂(MoO₄)₃ when the precursor is sintered at 900°C. In counterpart of monoclinic Gd₂MoO₆, however, the monoclinic structure remains unchanged when the precursor is sintered at a temperature ranging from 600°C to 900°C. Intense visible emissions of Er³⁺ attributed to the transitions of ²H_11/2, ⁴S_3/2–⁴I_15/2 at 520 and 550 nm, and ⁴F_9/2–⁴I_15/2 at 650 nm have been observed upon an excitation with a UV source and a 980 nm laser diode, and the involved mechanisms have been explained. It is quite interesting to observe obvious differences both in the excitation and the upconversion emission spectra of Er³⁺/Yb³⁺-codoped Gd₂(MoO₄)₃ respectively with monoclinic and orthorhombic structure. The quadratic dependence of fluorescence on excitation laser power has confirmed that two-photons contribute to upconversion of the green–red emissions.     

Optical temperature sensor based on up-conversion fluorescence emission in Yb3+:Er3+ co-doped ceramics glass

Yb3+:Er3+co-doped oxy-fluoride ceramics glass has been prepared.The mechanism of up-conversion emissions about Er3+was discussed,and the temperature properties of green up-conversion fluorescence between 303 and 823 K were investigated.The results show that the sensitivity of this sample reaches its maximum value,about 0.0047 K 1,when the temperature is 383 K,indicating that this kind of sample can be used as high temperature and high sensitivity optical temperature sensor.