镱掺杂钼酸铅的光谱和EPR谱的理论研究

该文表达了一个研究Yb³⁺掺杂PbMoO₄晶体的光谱和电子顺磁共振谱(EPR)的理论方法. 采用晶体场理论,推导了有关光谱和电子顺磁共振谱的公式. 基于这些理论公式,构建了4f¹³电子组态在D_2d晶体对称下包括Zeeman磁相互作用的14阶能量矩阵. 通过对角化这一能量矩阵,研究了Yb³⁺掺杂PbMoO₄晶体的光谱和电子顺磁共振谱. 所得的理论结果与实验值很好符合. 而且,相关的晶体场参量也在研究中确定.     

Li+共掺杂GdTaO4:Eu3+发光增强效应的研究

测量了不同浓度Li+共掺杂下GdTaO4:Eu3+荧光粉材料的X射线衍射谱(XRD)、发射光谱以及红外透射谱,并应用Judd-Ofelt理论,由发射光谱得到Eu3+的光谱跃迁强度参数Ω2.发现Li+共掺杂有助于提高GdTaO4:Eu3+的发光强度,当x=0.06和0.10时,612 nm处的发光强度分别被提升了1.7倍和1.5倍.发光增加的原因是因为Li+的助熔剂效应有效提高了GdTaO4材料的结品性能,并抑制了Cd2O3和Ta2O5杂相的产生,而非所推测的掺Li+引起了配位场对称性降低,从而导致宇称禁戒的放宽.此时Gd0.92-xLixTaO4:Eu3+0.08材料不仪结晶性能较好,而且Gd2O3和Ta2O5杂相也相对较少,故而发光增强最为明显.     

Influence of Yb~(3+) concentration on the upconversion luminescence of oxyfluoride material doped with Er~(3+)

In this paper,a new upconversion luminescent material co-doped with Erbium and Ytterbium is reported. The upconversion luminescence transition routes and related properties are studied. The results show that the absorption and emission intensities under excitation of 980 nm laser increase with the increase of the Yb3+ concentration. The red emission is stronger than the green emission. The energy transfer process plays an important role in the upconversion mechanism.     

Optical Properties of Yb~(3 ) Doped Bi_2O_3-3B_2O_3 Glass

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Er~(3+)和Yb~(3+)/Er~(3+)掺杂对石英光纤中倍频的影响

实验研究了掺Er~(3+)和Yb~(3+)/Er~(3+)石英光纤中的倍频过程.测量了不同Er~(3+)和Yb~(3+)/Er~(3+)掺杂量的光纤倍频转换效率和光纤倍频预处理前后Er~(3+)发射可见荧光的强度,探讨了Er~(3+)和Yb~(3+)掺杂对光纤中倍频过程的影响.     

Yb~(3+)/Er~(3+)掺杂氟氧化物微晶玻璃的制备与发光性能

采用高温熔融法制备了Yb3+/Er3+掺杂的氟氧化物发光微晶玻璃,确定了最佳熔化温度(1 100℃)和退火温度(440℃,480℃)。测定得到基质玻璃的透过率为85%,掺入稀土后,透过率有所下降,并出现了稀土离子的特征吸收峰。980 nm半导体激光器(LD)激发下样品的上转换发射光谱存在4个明显的发射峰,分别为410,532,546和656 nm,对应于2H9/2→4I15/2,2H11/2→4I15/2,4S3/2→4I15/2和4F9/2→4I15/2跃迁。研究了不同Yb3+/Er3+(摩尔分数)和Er3+浓度对上转换发光强度的影响,当Yb3+∶Er3+=4∶1、Er3+摩尔分数为1.5%时,上转换发光强度达到最高。根据发光强度与泵浦功率之间的关系,确定了上转换发射均为双光子过程。讨论了Yb3+,Er3+离子间的能量传递,建立了上转换发光机制。     

YLiF4:Er3+,Yb3+中敏化剂浓度对发光的影响

用水热法合成了YLiF4：Er^3＋,Yh^3＋,Er^3＋的浓度固定为2mol％,Yb^3＋浓度变化范围是0～7mol％。在这个浓度范围内,980nm附近的吸收随着Yb^3＋浓度的增大而增强。用980nm激发得到的上转换发光强度随Yb^3＋浓度的增大而增强。在Yb^3＋浓度低于6mol％时,上转换发光强度随Yb^3＋浓度的增大变化的比较缓慢,当Yb^3＋浓度超过6mol％时,上转换发光突然增强。以Yb^3＋浓度是2mol％的样品为代表,研究了Er^3＋对应红光、绿光发射的激发光谱,并测试了不同波长激发下的红光发射和绿光发射,证明红光发射是来源于^4F9/2→^2I15/2,绿光是来自^4S3/2→^2I15/2和^2H11/2→^2I15/2。它们的上转换过程都是双光子过程。     

掺镱氟铅硅酸盐玻璃光谱性质研究

采用高温熔融法制备了组成为(80-x)SiO2·xPbO·(17~19)( R2O+RF) ·(1~3)Yb2O3（R=Li、Na、K）（mol%）的掺镱氟铅硅酸盐玻璃,测量了样品的吸收光谱、荧光光谱和荧光寿命,利用McCumber理论计算了该玻璃系统中Yb3+离子2F5/2→2F7/2能级跃迁受激发射截面.结果表明,该玻璃在1 013 nm处的σemi为0.21×10－20 cm2,荧光有效线宽为94.8 nm,荧光寿命为2.36 ms.激光性能评价结果表明,该玻璃是实现大能量超短脉冲激光的理想材料.     

Up-conversion luminescence properties and energy transfer of Er~(3+)/Yb~(3+)co-doped oxyfluoride glass ceramic containing CaF_2 nano-crystals

The Er3+/Yb3+co-doped transparent oxyfluoride glass-ceramics containing CaF2nano-crystals were successfully prepared. After heat treatments, transmission electron microscopy(TEM) images showed that CaF2nano-crystals of 20–30 nm in diameter precipitated uniformly in the glass matrix. Comparing with the host glass, high efficiency upconversion luminescence of Er3+at 540 nm and 658 nm was observed in the glass ceramics under the excitation of 980 nm. Moreover,the size of the precipitated nano-crystals can be controlled by heat-treatment temperature and time. With the increase of the nano-crystal size, the intensity of the red emission increased more rapidly than that of the green emission. The energy transfer process of Er3+and Yb3+was convinced and the possible mechanism of Er3+up-conversion was discussed.     

Calculating Hamiltonian parameters for Yb~(3+) in a low-symmetry lattice site,and fitting the structure and levels of Yb~(3+) :TaO_4 (= Gd,Y,and Sc)

An iterative method is used to find the values of the Hamiltonian parameters for Yb3+ in a given low-symmetry crystalline site.Samples of Yb3+:RETaO4(RE = Gd,Y,and Sc) were prepared and their structures were determined.Based on the obtained structural data,their orbital-spin parameters and crystal field parameters were fitted by the superposition model(SM).Using the crystal field parameters obtained by the SM fitting as the initial parameters,the Hamiltonian parameters were fitted iteratively.The calculated and experimental energy levels for Yb3+:RETaO4 are consistent,and the maximal mean-root-square deviation is only 2.84 cm-1,indicating that the method is effective to determine the Hamiltonian parameters of Yb3+ in low-symmetry crystalline sites.     

NaLa(MoO4)2∶Eu3+的水热调控合成与发光特性研究

采用水热法合成了不同粒径的NaLa(MoO₄)₂∶Eu³⁺微晶.通过调节乙二醇浓度和反应时间,研究了NaLa(MoO₄)₂∶Eu³⁺微晶的形貌演变过程,在水热条件下180 ℃反应16 h获得了均一梭子形NaLa(MoO₄)₂∶Eu³⁺微晶,其晶粒长度约为2.0 μm.荧光光谱分析表明,Eu³⁺取代了NaLa(MoO₄)₂中La³⁺的格位, Eu³⁺在613 nm处红光发射(⁵D₀–⁷F₂跃迁)的浓度猝灭机理是电偶极-电四极相互作用,并发生了Eu³⁺( ⁵D₁ ) + Eu³⁺(⁷F₀ )→ Eu³⁺( ⁵D₀ ) + Eu³⁺(⁷F₃) 交叉弛豫,由此导致浓度猝灭. 关键词： 钼酸盐 水热法 稀土离子 发光     

Na2SrSiO4：Ce^3＋,Tb^3＋,Yb^3＋的制备及近红外量子剪裁发光性质

采用高温固相法制备了新型N a2SrS iO4：C e3＋,Tb3＋,Yb3＋的近红外发光材料。对样品可见和近红外激发光谱、发射光谱及荧光寿命的研究表明,N a2SrS iO4：C e3＋,Tb3＋,Yb3＋中存在高效的Tb3＋→Yb3＋的量子剪裁下转换效应,下转换量子效率约为182.4%。Ce3＋的共掺大大提高了样品的紫外光吸收,显著敏化了样品的近红外发光效率。研究了Ce3＋,Tb3＋和Yb3＋掺入量对其发光性质的影响。结果表明,当Ce3＋的浓度为2%,Tb3＋的浓度为13%和Y b3＋的浓度为16%时,样品的近红外发光最强。     

大模场面积掺镱双包层光纤研究

采用改进的化学汽相沉积工艺,沉积了光纤阻挡层和疏松层.结合溶液掺杂技术,研究了疏松层沉积温度、镱铝共掺工艺条件对掺镱浓度的影响,研究了大模场面积纤芯的制备工艺,实现了高浓度大模场面积掺镱双包层光纤的研制.测量并分析了光纤的光学性能参数及其激光特性,光纤芯径达到30 μm,纤芯摻镱浓度提高到4 000 ppm以上,芯数值孔径降至0.07,光纤的模场面积从113 μm2 提高到1 256 μm2,光纤的非线性效应阈值功率由12 W提高到大于128 W.     

可用于白光LED的红色荧光粉NaGdTiO4:Eu3+的制备及光学性质

采用高温固相反应法制备了NaGdTiO4∶Eu3+红色荧光粉.利用X射线衍射和荧光光谱对NaGdTiO4∶Eu3+粉末进行了表征,研究了TiO2含量和Eu3+掺杂摩尔分数对粉末晶体结构和发光性能的影响.当TiO2的量在当量反应基础上增加50%时,制得了单一正交相NaGdTiO4.荧光光谱测试结果显示,样品在紫外区存在强...     

LaPO4:Eu3+@SiO2核壳结构发光纳米棒的制备与表征

在不加任何表面活性剂的条件下,通过水热法直接合成了LaPO4:Eu3+纳米棒,并采用溶胶-凝胶法在其表面修饰了一层SiO2,得到了LaPO4:Eu3+@SiO2纳米棒.XRD分析表明,样品包覆前后均属于单斜晶系的独居石型的LaPO4.FTIR分析表明,LaPO4:Eu3+粒子与SiO2是以化学键的形式结合在一起.由TE...     

Nd3+掺杂GdTaO4的吸收光谱分析和晶场计算

采用提拉法生长出了钕掺杂钽酸钆重闪烁单斜激光晶体(Nd³⁺:GdTaO₄). 分别测试了该晶体a向、b向和c向的吸收光谱(波段为260-2000 nm), 对其中Nd³⁺ 的实验能级进行了分析指认. 确定了Nd³⁺:GdTaO₄的102个实验Stark能级, 拟合了其自由离子参数和晶体场参数, 均方根误差(拟合精度) σ 为12.66 cm^-1. 并将拟合得到的Nd³⁺:GdTaO₄实验结果与文献中已报道的Nd³⁺:Gd_xLu_1-xTaO₄ (x=0.85)的自由离子参数和晶体场参数进行了比较. 结果表明, 参数化Stark能级的拟合结果与实验光谱符合得较好.     

Er3+/Yb3+共掺碲酸盐玻璃陶瓷的光谱性质

利用熔融淬火法在900℃下成功制备出原料比为60TeO2 -10CaF2 -25 H3 BO3-1 Er2 O3-4Yb2 O3的Er3+/Yb3+共掺杂透明玻璃陶瓷.利用XRD和TEM验证了玻璃陶瓷中存在Er2Te5O13纳米微晶,并由Raman测试得知其声子能量为886 cm-1.分别测量了其上转换和下转换发射谱,...     

Tm~(3+)/Yb~(3+)共掺激光晶体的本征光学双稳特性分析与参数优化

理论研究了650nm激光雪崩抽运Tm3+/Yb3+共掺激光晶体的本征光学双稳态.基于系统的非线性耦合速率方程理论,数值分析了Tm3+/Yb3+离子能级布居数的本征光学双稳性、系统参数对光学双稳态的影响和双稳迟滞回线的动态变化.数值结果给出了光子雪崩机制下Tm3+/Yb3+共掺激光晶体的可见与红外光谱发光的本征光学双稳态;指出了通过优化Tm3+/Yb3+离子浓度比,选取低声子能晶体基质和采用晶体冷却技术,以及调谐抽运光与Tm3+离子激发态跃迁能隙满足共振频率匹配,可以有效地增强本征光学双稳效应;通过微调谐抽运光波长和控制抽运光强变化速率,可以实现动态调控的本征光学双稳态.     

碱金属氟化物对掺Yb3+氟磷酸盐玻璃析晶稳定性和光谱性质的影响

研究了碱金属氟化物对掺Yb3 氟磷玻璃的光谱性质和析晶稳定性能的影响.运用倒易法计算了Yb3 的发射截面.结果显示,LiF的引入对吸收和发射截面的提高作用较大并出现最佳引入量极值,其次为KF.碱金属氟化物的引入可提高二元体系的析晶稳定性能,使玻璃网络结构得到改善;拉曼光谱显示二元体系中引入YbF<,3>后玻璃网络结构得到增强,而在引入碱金属氟化物的三元体系中掺杂YbF<,3>后破坏了网络完整性,降低系统析晶稳定性能.     

Shape controllable synthesis and enhanced upconversion photoluminescence of β-NaGdF_4:Yb~(3+), Er~(3+) nanocrystals by introducing Mg~(2+)

Different concentrations of Mg~(2+) -doped hexagonal phase NaGdF_4:Yb~(3+), Er~(3+)nanocrystals(NCs) were synthesized by a modified solvothermal method. Successful codoping of Mg~(2+)ions in upconversion nanoparticles(UCNPs) was supported by XRD, SEM, EDS, and PL analyses. The effects of Mg~(2+)doping on the morphology and the intensity of the upconversion(UC) emission were discussed in detail. It turned out that with the concentration of Mg~(2+)increasing, the morphology of the nanoparticles turn to change gradually and the UC emission was increasing gradually as well. Notably the UC fluorescence intensities of Er~(3+)were gradually improved owing to the codoped Mg~(2+)and then achieved a maximum level as the concentration of Mg~(2+)ions was 60 mol% from the amendment of the crystal structure of β-NaGdF_4:Yb~(3+),Er~(3+)nanoparticles. Moreover, the UC luminescence properties of the rare-earth(Yb3+, Er~(3+)) ions codoped NaGdF_4 nanocrystals were investigated in detail under 980-nm excitation.