Er3+-doped Multicomponent Silicate Glass Planar Waveguides Prepared by Sol-Gel Processing

Erbium doped silica-titania planar waveguides, co-doped with ytterbium and aluminum, have been prepared by sol-gel processing, using multilayer spin-coating deposition on silicon or silica glass substrates. The Er3+ doping level varied between 0 and 2 at.%, while Yb3+ varied from 0 to 3 at.%. Aluminum was incorporated up to 15 at.% Al and it was found to have no significant effect on the refractive index of the silica-titania (80 : 20 mol%) matrix. The Er3+ fluorescence emission was flat within ±0.5 dB, between 1520 and 1560 nm. The corresponding 4I13/2 metastable level lifetime was found to decrease from 6.1 to 3.5 ms, as the Er concentration increased from 0.1 to 0.5 at.%, for films co-doped with 0.5 at.% Yb and 10 at.% Al and the fluorescence decay was essentially single exponential below a Er quenching concentration of 0.5 at.% (1.1 × 1020 ions/cm3). The lifetime appears to be limited by Er-Er interactions at higher rare-earth ion concentrations and by residual OH species in the sol-gel derived waveguides. Vacuum heat treatment at a temperature near 570°C was somewhat effective in increasing the Er fluorescence lifetime, whereas reactive atmosphere processing in CCl4 or Cl2 at a similar temperature appeared to be less effective.     

Synthesis of hexagonal-phase core-shell NaYF4 nanocrystals with tunable upconversion fluorescence

Hexagonal-phase core-shell-structured NaYF 4:Yb,Tm@beta-NaYF 4:Yb,Er and beta-NaYF 4:Yb,Tm@beta-NaYF 4:Yb,Er@beta-NaYF 4:Yb,Tm nanocrystals were synthesized by a seeded growth approach. beta-NaYF 4:Yb,Tm nanocrystals with 20 nm diameter were used as seed crystals to induce the growth of beta-NaYF 4:Yb,Er and then beta-NaYF 4:Yb,Tm crystals, resulting in the formation of core-shell-structured nanocrystals with upconverting lanthanide ions Tm and Er doped in the core and shell, respectively.     

Ga2O3-La2O3-Yb2O3-Er2O3(HO2O3)体系光谱性质的研究

根据稀土离子能级的特点,对Ga2O3-La2O3-Yb2O3-Er2O3(HO2O3)体系的光谱性质进行了探讨,发现它们有二类发光性质:Stokes发光和反Stokes发光,研究了发光强度和发射波长与掺杂离子的依赖关系,观察到由能量的共振转移引起的荧光浓度猝灭现象,并取得了最大发光强度时的掺杂离子浓度和一些规律性结果.     

铋酸盐铒玻璃在1.54 μm处的荧光特性研究

The bismuth glasses with Er3+ and Er3+/Yb3+ co doped were fabricated by the technique of high temperature melting. The absorption and fluorescence spectra, fluorescence lifetime and FWHM were measured. The explanation of concentration quenching in case of high level Er3＋ doped the bismuth glasses is given. The sensitizing of Yb3＋ to Er3＋ in Er3＋/Yb3＋ co doped bismuth glasses is discussed. The explanation of the influence on absorption and fluorescence spectra, fluorescence lifetime and FWHM in case of the change of Er3+ or Yb3+ in bismuth glasses with Er3+/Yb3+ co doped is given. It is found that the change of Er3+ content has obviously influenced the fluorescence lifetime and FWHM while the change of Yb3+ content has remarkably influenced the absorption and fluorescence intensity. The band at around 1.54 μm in Er3+/Yb3+ co doped bismuth glass reaches 76 nm and the fluorescence lifetime is 0.55 ms.     

稀土掺杂Ba0.6Sr0.4TiO3薄膜的介电及发光性能

以钛酸锶钡和稀土氧化物粉末靶为靶材, 用离子束溅射法在MgO(100)和Si(100)基片上组合制备了不同掺杂浓度的Ba0.6Sr0.4TiO3:Re(BST:Re)薄膜样品阵列. 沉积得到的多层无定形薄膜经低温扩散、高温晶化, 形成BST:Re多晶薄膜. 以扫描近场微波显微镜测定BST:Re/MgO(Re=Er, Eu, Pr/Al)样品的介电常数, 研究掺杂种类及掺杂浓度对BST薄膜介电常数的影响. 结果表明, 稀土离子的适量掺杂使BST薄膜介电常数有所提高, 其中, Er3+和Eu3+的最佳掺杂浓度分别为4.5%及5.7%(原子分数) 左右时, 介电常数值达到最高. 而共掺杂Pr3+和Al3+的样品则在n(AL):n(Pr)为4-8之间介电性能最佳. 另外, 测量了BST:Re/Si(Re=Er, Eu)样品的光致发光谱, 发现Er3+和Eu3+在BST薄膜样品中的发光猝灭浓度分别为4.20%和8.95%(原子分数).     

Tuning of the structure and emission spectra of upconversion nanocrystals by alkali ion doping

Recently, lanthanide based nanocrystals with upconversion fluorescence emission have attracted a lot of interest and the nanocrystals have been used for bioimaging, biodetection, and therapeutic applications. Use of the nanocrystals for multiplexed detection has also been explored; however, nanocrystals with multicolor emission are required. Some efforts have been made to tune the emission spectra of the nanocrystals based on manipulation of upconverting lanthanide ions doped in the crystals or creation of core/shell structures. In this work, alkali ions with an ionic radius slightly larger or smaller than Na such as Li and K were doped into NaYF(4):Yb,Er nanocrystals and their effect on the crystal structure and subsequently the upconversion emission spectra were studied. It was found that the phase transition occurs in the nanocrystals when a different amount of Li and K was doped. Furthermore, the intensity ratios between the blue, green, and red emission peaks changed accordingly, and make it possible to tune the upconversion fluorescence of the nanocrystals by Li and K doping.     

Yb:Er:Tm:LiTaO3的上转换发白光性能研究

980 nm脉冲激光激发下,首次通过高温固相法制备Yb(10%):Er(1%):Tm(1%):LiTaO3(摩尔分数)多晶粉并实现室温上转换白光.X射线粉末衍射测试结果表明,Yb:Er:Tm:LiTaO3中的掺杂离子并没有改变晶格结构,以取代的方式存在于钽酸锂晶格中.结合功率曲线测试结果和上转换机制研究发现,产生上转换蓝光的Tm3+离子1G4态的布居主要来自双光子同时吸收过程.而单光子上转换输出的红光,则由Tm3+和Er3+离子之间的交叉弛豫过程产生,即3F2/3(Tm3+)+4I15/2(Er3+)→3H6(Tm3+)+4I9/2(Er3+).上转换绿光来源于Yb/Er离子对的二次能量传递.     

Photoluminescent Property Effect of Sc3+ on Er3+/y3+/yb3+ Doped Al2O3 Powders

The photoluminescence (PL) property effect of Sc3+ on the Er3+/Y3+/Yb3+ doped Al2O3 powders prepared by sol-gel method has been investigated. The X-ray diffraction (XRD) and transmission electron microscopy (TEM) implied that the distribution of dopants (Er3+ , Y3+ , Yb3+ , Sc3+) was improved effectively with the rise of Sc3+ concentration. The Fourier transform infrared spectra (FTIR) results demonstrated that the ligand around the quenching center -OH and the population of -OH were altered by introducing different amounts of Sc3+ . The PL intensity centered at 1530 nm was increasingly improved with the rise of Sc3+ concentration, as well as the corresponding full widths at the half maximum (FWHM) and lifetime. The optimized PL intensity was 4.7 times higher than that non-Sc3+ doped sample for the Al2O3 powders codoped with 10mol% Sc3+ . This material can be promising candidates for optical fiber amplifier.     

Er3+-Yb3+共掺纳米TiO2上转换光催化杀菌作用研究

采用溶胶凝胶法合成了稀土离子Er^3＋-Yb^3＋共掺杂的纳米TiO2晶体粉末,利用XRD,UV-VIS吸收光谱及上转换发射光谱对其结构和光学特性进行了表征．以致病性嗜水气单胞菌为实验菌株,以980nm激光为激发光源,考察了室温下Er^3＋-Yb^3＋共掺杂纳米TiO2的光催化杀菌性能．结果表明,稀土离子掺杂的纳米TiO2可以通过上转换发光的途径增加TiO2对可见光的利用率,从而实现TiO2在可见光和近红外光范围的光催化氧化杀菌作用．     

Mn~(2+)掺杂NaBiF_4∶Yb/Er体系的可调控上转换发光

采用溶剂热法制备了不同Mn~(2+)掺杂量的NaBiF_4∶Yb/Er/Mn上转换发光体系,研究了其形貌、晶相、上转换发光性能随Mn~(2+)掺杂量的变化,并探讨了该体系的能量传递机理.实验结果表明,Mn~(2+)的掺杂不会引起NaBiF_4从六方相转变为立方相,但会增大其尺寸;同时在NaBiF_4体系中,Mn~(2+)可以与Er~(3+)进行能量传递,使红光发射得到增强,并且随着Mn~(2+)浓度的增加,红/绿光发射强度比也会随之增大.此外,还考察了NaBiF_4∶Yb/Er/Mn体系的变温发射光谱,发现当温度升高时,红/绿光强度比以及520 nm绿光与540 nm绿光发射强度比都总体上呈增大趋势.     

La0.67Ca0.33Mn1-xAlxO3体系的结构和输运特性研究

研究了Al离子的Mn位替代对巨磁阻材料La0.67Ca0.33MnO3体系的结构和输运特性的影响。结果表明,随Al3 替代量的增加,在整个替代范围内,晶胞体积表现出单调减小的规律。体系的电阻率急剧增加,绝缘体 金属转变温度TIM向低温方向移动,且与Al3 替代量存在线性关联。对少量Al3 替代量,在T>TIM的高温区域体系的输运特性满足热激活模型,在T相似文献   

Formation Enthalpy Calculation of Oxygen Vacancy Defect in Doped Lithium Niobate Crystals

The relationship between temperature and oxygen vacancy concentration is deduced in this paper. Based on the data of thermal weight-loss experiment, the formation enthalpies of congruent and several doped LN crystals have been calculated. It was found that the formation enthalpy of oxygen vacancies can be decreased evidently by doping valence-changeable ions. The experimental results were discussed and a new reduction process of the photorefractive LN crystal at a relatively low temperature was proposed, and the reduced crystals showed a good effect in practical use.     

Color tuning by co-doping of Er doped TiO2 phosphors within a fixed Er concentration

In this paper, we report the color tuning of Er doped TiO₂ upconversion phosphors within a fixed Er concentration using 976 nm semiconductor laser diode excitation. By codoping with Mo, Yb or Li ions in the Er doped TiO₂, the green and red upconversion emissions from the ²H_11/2/⁴S_3/2 → ⁴I_15/2 and ⁴F_9/2 → ⁴I_15/2 transitions of Er ions were enhanced selectively and the color output of Er doped TiO₂ could be tuned by different intensity ratios of green to red emissions. The two-photon absorption processes were responsible for the green and red upconversion emissions of Er–Mo, Er–Yb and Er–Li codoped TiO₂ phosphors, and the corresponding enhanced mechanisms were discussed. It is expected that these color tuned phosphors within a fixed Er concentration have great potential for applications in biology, displays and other optical technology.     

Dual energy converting nano-phosphors: upconversion luminescence and X-ray excited scintillation from a single composition of lanthanide-doped yttrium oxide

We report an upconverting nanomaterial composition, [Y(2)O(3); Yb (2%), Er (1%)], that converts both X-ray and high-fluence NIR irradiation to visible light. This composition is compared to a higher Yb(3+) doped composition, [Y(2)O(3); Yb (10%), Er (1%)], that displays diminished visible X-ray scintillation, but shows enhanced red wavelength centered upconversion emission. These nanocrystals have been characterized by TEM, X-ray diffraction, power-dependent upconversion luminescence, and X-ray scintillation spectroscopy. We further demonstrate that lithium ion doping of the [Y(2)O(3); Yb (2%), Er (1%)] nanoscale composition leads to enhanced X-ray and NIR excited emission intensities through the production of nanoparticles that feature slightly enhanced sizes and increased crystallinity.     

Nanoparticle enabled thermal control of ions in liquid crystals

Typically, ionic species in thermotropic liquid crystals are nearly fully ionised. Therefore, the concentration of mobile ions practically does not depend on the temperature. Interestingly, the same liquid crystals doped with nanoparticles exhibit totally different behaviour. The concentration of mobile ions become temperature dependent. This paper reports the effects of the temperature on the concentration of ions in liquid crystal nanocolloids. Liquid crystals doped with both 100% pure and contaminated nanoparticles are considered. Regardless the ionic purity of nanodopants, the concentration of mobile ions in liquid crystal nanocolloids increases towards the saturation as their temperature goes up. The magnitude of this saturation level equals the initial concentration of ions in liquid crystals doped with 100% pure nanoparticles. The temperature induced release of ions by contaminated nanoparticles in liquid crystals increases the above-mentioned saturation level. While the dispersion of 100% pure nanoparticles in liquid crystals leads to the temperature-dependent purification only, the use of contaminated nanoparticles results in the temperature-driven switching between the purification and contamination regimes enabling thermal control of ions.     

YAG∶Ce体系中稀土离子掺杂对Ce3+的光谱性能的影响

采用高温固相法合成了一系列的(Y0.95Ln0.01Ce0.04)3Al5O12(简称YAG∶Ce,Ln), 系统地研究了此体系中的Ln3+对Ce3+的发光强度的影响. 结果表明, 在YAG∶Ce的体系中, La3+, Gd3+, Lu3+等光学透明离子的少量掺杂对Ce3+的发光强度的影响不大; 掺入少量的Pr3+, Sm3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+等稀土离子, 由于它们的能级与Ce3+的能级有交叠, 使它们之间存在着竞争吸收或能量转移, 对Ce3+的发光有较明显的变化, 其中, Pr3+和Sm3+的掺入使其在红光区有发射峰, 可以增加YAG∶Ce的红色成分以提高显色性; Nd3+, Eu3+和Yb3+对Ce3+的发光有严重的猝灭作用.     

Ag/Yb掺杂对Ca_3Co_(3.9)Cu_(0.1)O_(9-δ)热电性能的影响

采用溶胶凝胶及冷压方法,通过在Ca_3Co_(3.9)Cu_(0.1)O_(9-δ)体系中引入不同量的Ag~+或Yb~(3+)离子来调控体系的热电性能,制备了可在300~880 K下稳定存在且热电性能优良的陶瓷材料Ca_(3-x)Ag_xCo_(3.9)Cu_(0.1)O_(9-δ)(x=0.1,0.15,0.2,0.3)和Ca_(3-y)Yb_yCo_(3.9)Cu_(0.1)O_(9-δ)(y=0.05,0.1,0.2,0.3).通过X射线衍射(XRD)和扫描电子显微镜(SEM)等测试手段对产物进行了表征,结果显示所制备的样品纯度较高,晶粒均匀,晶粒间较致密.适量的Ag~+,Yb~(3+)离子取代Ca~(2+)离子固溶到晶体中使制备的双掺杂材料晶胞体积发生了变化,但并未引起晶体对称结构的变化.电阻率和Seebeck系数的表征结果说明双掺杂优化了载流子的浓度,随着温度的升高电阻率不断减小,Seebeck系数不断增大.经过计算可知Seebeck系数的增大还有电子有效质量的贡献.热导率表征结果显示双掺杂体系的热导率随着温度的升高而减小,其中声子热导依然起主要作用,这与单掺杂体系的结果一致.随着温度的升高,双掺杂样品Ca_(2.7)Ag_(0.3)Co_(3.9)Cu_(0.1)O_(9-δ)在880 K下ZT值达到最大,为0.2.     

Ag~+,Sr~(2+),Yb~(3+)双掺杂对Ca_3Co_4O_(9-δ)热电性能的影响

采用溶胶-凝胶和冷压方法,在Ca3Co4O9-δ体系中引入不同量的Ag~+,Sr~(2+)或Yb~(3+)离子制备了可在300~870 K下稳定存在且热电性能优良的陶瓷材料Ca_(3-x-y)Ag_xSr_yCo_4O_(9-δ),Ca_(3-x-z)Ag_xYb_zCo_4O_(9-δ)和Ca_(3-y-z)Sr_yYb_zCo_4O_(9-δ)(x,y,z=0.1,0.15,0.2).通过X射线衍射(XRD)、傅里叶变换红外光谱(IR)和扫描电子显微镜(SEM)等手段对产物进行表征.结果显示,所制备的样品纯度较高,晶粒均匀,晶粒间较致密,适量的Ag~+,Sr~(2+),Yb~(3+)离子取代Ca~(2+)离子固溶到晶体中使制备的双掺杂材料晶胞体积发生了变化,但并未引起晶体对称结构的变化.电阻率和Seebeck系数结果表明,双掺杂优化了样品载流子的浓度,使样品电阻率不断减小,并使Seebeck系数的值不断增大.经过计算可知,Seebeck系数随电子有效质量的增大而增大.热导率结果表明,双掺杂的样品热导率随掺杂元素的不同而变化,计算结果显示声子热导依然在样品中占据主体贡献,这与Ca_3Co_4O_(9-δ)单掺杂Ag~+,Sr~(2+)或Yb~(3+)的结果吻合.随着温度的升高,双掺杂样品Ca_(2.7)Ag_(0.2)Yb_(0.1)Co_4O_(9-δ)在870 K下热电优值(ZT)值达到最大(0.18).     

Controllable synthesis and up-conversion properties of tetragonal BaYF5:Yb/Ln (Ln=Er, Tm, and Ho) nanocrystals

The nanocrystals (NCs) of tetragonal barium yttrium fluoride (BaYF(5)) doped 1 mol% Ln(3+) (Ln=Er, Tm, Ho) and 20 mol% Yb(3+) with different morphologies and sizes have been successfully synthesized through a facile hydrothermal method. The influences of pH values of the initial solution and fluorine sources on the final structure and morphology of the products have been well investigated. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM) were used to characterize the size, structure and morphology of these samples prepared at different conditions. And it is found that BaYF(5):Yb/Ln NCs prepared at pH value of 10 using NaBF(4) as F(-) source have a uniform spherical morphology with average diameter of 25 nm. Additionally, the up-conversion (UC) properties of Yb/Er, Yb/Tm, and Yb/Ho doped BaYF(5) nanoparticles were also discussed. Under 980 nm laser excitation, the BaYF(5):Yb/Er, BaYF(5):Yb/Tm, and BaYF(5):Yb/Ho NCs exhibit green, whitish blue, and yellow green UC luminescence, respectively. The luminescence mechanisms for the doped lanthanide ions were thoroughly analyzed.     

Local order around rare earth ions during the devitrification of oxyfluoride glasses

Erbium L(3)-edge extended x-ray absorption fine structure (EXAFS) measurements were performed on rare earth doped fluorosilicate and fluoroborate glasses and glass ceramics. The well known nucleating effects of erbium ions for the crystallization of cubic lead fluoride (based on x-ray diffraction measurements) and the fact that the rare earth ions are present in the crystalline phase (as indicated by Er(3+) emission spectra) seem in contradiction with the present EXAFS analysis, which indicates a lack of medium range structural ordering around the Er(3+) ions and suggests that the lead fluoride crystallization does not occur in the nearest neighbor distance of the rare earth ion. Molecular dynamics simulations of the devitrification process of a lead fluoride glass doped with Er(3+) ions were performed, and results indicate that Er(3+) ions lower the devitrification temperature of PbF(2), in good agreement with the experimental results. The genuine role of Er(3+) ions in the devitrification process of PbF(2) has been investigated. Although Er(3+) ions could indeed act as seeds for crystallization, as experiments suggest, molecular dynamics simulation results corroborate the experimental EXAFS observation that the devitrification does not occur at its nearest neighbor distance.