不同掺杂浓度Tm3+∶LiLuF4单晶的1800 nm荧光发射

采用坩埚下降法生长了Tm3+掺杂浓度为0.45％,0.90％,1.63％与3.25％(摩尔分数,x)的LiLuF4单晶.测试了样品的电感耦合等离子体原子发射光谱(ICP-AES)、X射线衍射(XRD)谱、吸收光谱(1400-2000 nm),并且分析比较了808 nm半导体激光器(LD)激发下荧光光谱.结果表明:当Tm3+的浓度从0.45％变化到3.25％时,1800 nm处的荧光强度呈现了先增后减的趋势,当掺杂浓度约为0.90％时达到最大值,而位于1470 nm处的荧光强度则呈现了相反的趋势.Tm3+∶3F4能级的荧光衰减寿命随着掺杂浓度的增加不断减小.1800 nm处的这种荧光强度变化归结于Tm3+离子间的交叉驰豫效应(3H6,3H4→3F4,3F4)和自身的浓度猝灭效应.同时计算得到了浓度为0.90％的样品在1890 nm处的最大发射截面为0.392x 10-20 cm2.并且根据Judd-Ofelt理论所得寿命和测定的荧光寿命计算得到了3F→3H6的最大量子效率约为120％.     

不同掺杂浓度Tm3+：LiLuF4单晶的1800 nm荧光发射

采用坩埚下降法生长了Tm³⁺掺杂浓度为0.45%,0.90%,1.63%与3.25%（摩尔分数,x）的LiLuF₄单晶.测试了样品的电感耦合等离子体原子发射光谱（ICP-AES）、X射线衍射（XRD）谱、吸收光谱（1400-2000 nm）,并且分析比较了808 nm半导体激光器（LD）激发下荧光光谱. 结果表明：当Tm³⁺的浓度从0.45%变化到3.25%时,1800 nm处的荧光强度呈现了先增后减的趋势,当掺杂浓度约为0.90%时达到最大值,而位于1470 nm处的荧光强度则呈现了相反的趋势. Tm³⁺：³F₄能级的荧光衰减寿命随着掺杂浓度的增加不断减小. 1800 nm处的这种荧光强度变化归结于Tm³⁺离子间的交叉驰豫效应（³H₆,³H₄→³F₄,³F₄）和自身的浓度猝灭效应. 同时计算得到了浓度为0.90%的样品在1890 nm处的最大发射截面为0.392×10^-20 cm². 并且根据Judd-Ofelt 理论所得寿命和测定的荧光寿命计算得到了³F₄→³H₆的最大量子效率约为120%.     

Tm3+掺杂锗镓酸盐玻璃的2 μm中红外光谱特性

用高温熔融法制备了Tm2O2掺杂浓度分别为1.526%,3.006%,5.836%,11.028%,15.678%(质量分数,以下同)的65GeO2-12Ga2O3-10BaO-8Li2O-5La2O3(摩尔比)玻璃.从其吸收光谱特性出发,应用Judd-Ofelt理论,计算了Tm3+离子的J-O强度参数(Ω2,Ω4,Ω6)及Tm3+离子各激发态能级的自发跃迁几率、荧光分支比以及辐射寿命等光谱参量.在808 nm波长光的激发下,研究了不同Tm3+掺杂浓度玻璃在～1.47 μm与～1.8 μm的荧光特性,发现当Tm2O3掺杂浓度约达到～3.006%时,在1.8 μm处的荧光强度达最大;然后随着掺杂浓度的增大,其荧光强度反而降低.本文从Tm3+离子间的能量交叉弛豫效应与浓度猝灭效应解释了这一荧光强度变化的现象.同时,根据Mc-Cumber理论,计算了Tm3+离子能级3F4→3H6(1.8 μm)跃迁的吸收截面和受激发射截面,该荧光的受激发射截面峰值比氟锆铝酸盐玻璃大.由于该玻璃材料表现出较好的光谱性能,因此该材料可望成为～2.0 μm波段中红外光纤激光器的候选基质材料.     

绿色荧光粉Ba2-xB2O5:xTb3+的制备及发光性能研究

采用高温固相法合成了Ba2-xB2O5:xTb3+绿色荧光粉。XRD图谱表明合成物质为纯相的Ba2B2O5晶体。该样品在256 nm(4f8→4f75d1)处有最强激发;有4个发射峰,分别位于489 nm(5D4→7F6),545 nm(5D4→7F5),585 nm(5D4→7F4)和622 nm(5D4→7F3);其中在545 nm处有最强发射。随着Tb3+掺杂浓度的不同,激发峰与发射峰的强度先增大后减小,当x=0.7时最佳。研究了电荷补偿剂Na+对发光性能的影响,样品的发射光谱强度随Na+掺杂浓度的增大而增大,当掺杂浓度达到或超过Tb3+浓度后发射光谱强度下降。     

Dy~(3+)掺杂Ge-Ga-Se-KBr硫卤玻璃近红外和中红外发光特性研究

用熔融淬冷法制备了系列掺杂浓度的Dy3+∶Ge-Ga-Se-KBr硫卤玻璃样品,测试了样品的折射率、吸收光谱、近红外及中红外荧光谱。应用Judd-Ofelt理论计算了Dy3+离子的强度参数(Ωi,i=2,4,6)、自发辐射跃迁几率(A)、荧光分支比(β)和辐射寿命(τrad)等光谱参数。研究了810 nm激光泵浦下样品中红外荧光特性与掺杂浓度之间的关系,利用McCumber(MC)和Futchbauer-Ladenburg(FL)理论分别计算了常温Dy3+:6F5/2→6H9/2(2.17μm),6F11/2(6H9/2)→6H13/2(2.47)和6H13/2→6H15/2(2.86μm)中红外荧光的受激发射截面。     

近紫外激发Sm3+与Sr2+,Ba2+,Bi3+共掺杂的La1/3NbO3的发光性质

通过高温固相反应合成了La1/3NbO3∶Sm3+荧光粉.样品的荧光光谱表明,La1/3NbO3∶Sm3+荧光粉最强的激发带在406 nm,对应于Sm3+的6H5/2→4K11/2跃迁,属于近紫外区(365～410 nm).当激发波长为406nm时,样品的最强发射峰位于596 nm,是由Sm3+的4G5/2→6H7/2跃迁而产生的.因此,La1/3NbO3∶Sm3+可以作为基于近紫外激发的白光发光二极管(LED)的红光材料.而且,La位共掺杂Sr2+,Ba2+和Bi3+使样品的荧光强度大大增加,在最佳掺杂浓度时的量子产率分别为5.4%,7.5%和5.3%.     

YVO_4:Eu~(3+),Al~(3+)荧光粉的制备及荧光性能研究

用高温固相法制备了Al3+掺杂的YVO4:Eu3+荧光粉。采用X射线粉末衍射(XRD)、环境扫描电镜(SEM)、荧光光谱(FL)等对样品进行了表征。分析了Al3+掺杂对YVO4:Eu样品晶体结构、晶胞参数和荧光性能的影响,并探讨了烧结温度对光谱性能的影响。研究结果表明:当Eu3+的浓度x(摩尔百分比)为4%,Al3+的浓度为1.5%时,在1100℃下烧结的样品其荧光性能最好,5D0→7F2处的发光强度约为未掺Al3+的2.5倍。由于Eu3+的7F2→5L6跃迁吸收,YVO4:Eu3+,Al3+荧光粉可在395 nm被有效激发。因此,YVO4:Eu3+,Al3+可以作为近紫外激发的白光LED红色荧光粉。     

铕掺杂硅钛柱撑蒙脱土的合成及发光性能研究

采用溶胶凝胶法制备了Eu3+掺杂的硅钛柱撑蒙脱土(Si-Ti-MT),运用XRD,SEM-EDX和FT-IR对其结构进行了表征。结果表明,Eu3+掺杂的硅钛柱撑剂插入蒙脱土层之间,保持了蒙脱土层状结构。经荧光发射光谱和激发光谱分析可知,Si-Ti-MT是Eu3+发光的有效基体,其发射能级主要为Eu3+613 nm(5D0→7F2);激发光谱中表现了Eu3+的5个特征激发带,分别为363 nm(7F0→5D4),382 nm(7F0→5G2),395 nm(7F0→5L6),415 nm(7F0→5D1)和465 nm(7F0→5D2);热处理促进了Eu3+掺杂的硅钛柱撑蒙脱土的发光,且样品的荧光强度随着Eu3+掺杂量的增加而增强,不会发生浓度猝灭现象。     

一种上转换白光荧光粉的制备与发光性能研究

采用高温固相法制备了上转换白光荧光粉AlF3-YbF3:Er3+/Tm3+。通过XRD物相分析可知:上转换白光荧光粉AlF3-YbF3:Er3+/Tm3+是由三方AlF3相和正交YbF3相组成;利用发射光谱研究了该荧光粉的上转换发光性能,并且分析了当固定Er3+离子掺杂浓度时,Tm3+离子掺杂浓度对上转换白光荧光粉AlF3-YbF3:Er3+/Tm3+色度的影响,进而提出其上转换能量传递机制。结果表明:在980 nm激光激发下,波长为410 nm的紫光峰、550 nm的绿光峰和660 nm的红光峰分别对应于荧光粉中Er3+离子的2H9/2→4I15/2,4S3/2→4I15/2和4F9/2→4I15/2能级的跃迁,而波长为360 nm的紫外光峰、450 nm的蓝光峰、700 nm的红光峰,分别对应于荧光粉中Tm3+离子的1D2→3H6,1G4→3H6和1G4→3F4能级的跃迁,Er3+离子发出的光与Tm3+离子发出的光最终混合成色坐标为x=0.32,y=0.36的白光。此外,通过980 nm半导体激光器和EPM 2000 Dual-channel Joulemeter/Power meter测得该荧光粉最大上转换效率为6.90%。     

新型单基质白光荧光粉Sr3La1-x（PO4）3:xDy3+制备及发光性能

采用高温固相法合成了Sr3La1-x(PO4)3:xDy3+荧光粉,并对其结构和发光特性进行了研究。样品发射光谱呈多峰发射,主峰位于482,576和666 nm,分别对应Dy3+的4F9/2→6H15/2,4F9/2→6H13/2和4F9/2→6H11/2特征跃迁。监测不同发射峰,激发光谱峰位置不变,主激发峰位于348,362和385 nm,可以被InGaN管芯有效激发。分析了Dy3+掺杂浓度对样品发光强度的影响,确定Dy3+的最佳掺杂摩尔分数为10%。根据Dexter理论分析其浓度猝灭机理为电偶极-电偶极相互作用。不同Dy3+掺杂浓度样品发射光谱的色坐标均在白光区域内。     

Highly efficient blue up-conversion of Tm in Nd–Yb–Tm co-doped ZrF4-based fluoride glass

Up-conversion luminescence and energy-transfer processes in Nd³⁺, Yb³⁺ and Tm³⁺ co-doped ZrF₄-based fluoride glasses have been studied under 800 nm light excitation. Blue up-converted emission around 478 nm which can be assigned to the Tm³⁺:¹G₄→³H₆ transition, was strongly observed. Up-conversion luminescence intensity exhibited an YbF₃-concentration dependence. Among the Nd³⁺, Yb³⁺ and Tm³⁺, Nd³⁺ and Tm³⁺ have ground state absorption bands due to the (²H_9/2,⁴F_5/2)←⁴I_9/2 and ³F₄←³H₆ transitions, respectively, which can be directly pumped by 800 nm radiation. However, no emissions were observed in Tm³⁺ singly-doped and Tm³⁺–Yb³⁺ doubly-doped glasses under 800 nm excitation. Therefore, a possible up-conversion mechanism may be proposed as follows: energy-transfer firstly occurs from Nd³⁺ to Yb³⁺ when Nd³⁺ is excited by 800 nm light, then the energy is transferred from Yb³⁺ to Tm³⁺ which is in the excited state and, finally, blue up-conversion emission of Tm³⁺ is observed through the Tm³⁺:¹G₄→³H₆ transition.     

Effect of Zn2+ Ions on Upconversion Emission of Er3+ in Zn/Er:LiNbO3 Crystal

The effect of Zn2+ ions codoped on the upconversion emission of Er3+ ions in Er:LiNbO3 crystal under different excitation wavelength was reported.The upconversion emission spectra of Zn/Er:LiNbO3 follo...     

Ba3LaNa(PO4)3F:Tm3+, Dy3+: A tunable blue-white color emitting phosphor via energy transfer for UV white LEDs

A series of Tm^3+/Dy^3+co-doped Ba3 LaNa(PO4)3 F(BLNPF) phosphors were synthesized successfully via a high-temperature solid-reaction,and luminescence properties were investigated.Upon near violet excitation,BLNPF:Tm^3+,Dy^3+ phosphors exhibit Tm^3+:^1D2-^3 F4 and Dy^3+:^4 F(9/2)-^6 HJ(J=15/2,13/2,11/2)transitions with diffe rent luminescence intensity.The emitting color of the obtained products was found to shift from blue to white as a result of efficient energy transfer(ET) from Tm^3+to Dy^3+ions.According to photoluminescence emission intensity,the positive effect of activator on ET efficiency was calculated and the maximum ET efficiency was found around 72.6% with Dy^3+ concentration was 0.04.By means of Dexter's theoretical model,furthermore,dipole-dipole interaction was confirmed as the mechanism of energy transfer from Tm^3+ to Dy^3+ ions.The results suggested that BLNPF:Tm^3+,Dy^3+ phosphor might be a promising single-phased white-light-emitting phosphor for UV white-light LED.     

High-temperature High-pressure Hydrothermal Synthesis of Dy3＋-doped YNbO4 Single Crystal and Its Luminescence Properties

Single crystal Dy3＋ doped YNbO4phosphors were prepared via a high-temperature high-pressure hydrothermal procedure. Under excitation at 270 nm, the Dy3＋-doped YNbO4 phosphor shows bright white emission, which is composed of two strong bands at 492 and 576 nm corresponding to the characteristic 4F9/2→6H15/2 and aF9/2→6H13/2 transitions of Dy3＋, respectively. The dominant band was observed at 352 nm, which corresponds to the 6H15/2→6p7/2 transition of Dy3＋. Nearly white light was achieved at 2ex 270, 310 and 388 nm and the CIE（International Commission on Illumination） values were （0.3135, 0.3421）, （0.3088, 0.3380） and （0.3146, 0.3296）, respectively.     

单一基质白光荧光粉Na3Sc2(PO4)3∶Tm3+,Dy3+的合成及发光性质

采用高温固相法成功制备了Na₃Sc_2-x-y(PO₄)₃∶xTm³⁺,yDy³⁺荧光粉,利用X射线衍射仪、扫描电子显微镜和荧光光谱仪对荧光粉进行了物相、形貌和发光性能进行了表征。 在Na₃Sc₂(PO₄)₃∶0.06Tm³⁺,yDy³⁺荧光粉中,物质的量分数6%的Tm³⁺和6%的Dy³⁺在360 nm激发下呈现出白光发射,其发射光谱在460~685 nm范围内存在Tm³⁺位于457 nm的特征发射峰,对应于Tm³⁺的³H₆→¹D₂跃迁,以及Dy³⁺位于483、577和672 nm处的3个特征发射峰,分别对应于Dy³⁺的⁴F_9/2→⁶H_15/2、⁴F_9/2→⁶H_13/2和⁴F_9/2→⁶H_11/2的跃迁。 观测到Na₃Sc₂(PO₄)₃∶Tm³⁺荧光粉的发射光谱与Na₃Sc₂(PO₄)₃∶Dy³⁺的激发光谱有较好的重叠,且Tm³⁺的荧光寿命随Dy³⁺浓度的增加逐渐降低,因此在Na₃Sc₂(PO₄)₃∶Tm³⁺,Dy³⁺荧光粉中存在Tm³⁺向Dy³⁺的能量传递。 利用Dexter和Reisfeld近似分析了能量转移机制,发现从Tm³⁺到Dy³⁺的能量传递临界距离为1.6 nm,能量传递过程是通过偶极-偶极相互作用进行的。 Na₃Sc₂(PO₄)₃∶0.06Tm³⁺,0.06Dy³⁺荧光粉具有较好的耐受热猝灭性能,在423、473和523 K时的发射强度分别为298 K时发射强度的97.6%、89.2%和78.6%。 随着Dy³⁺浓度的增加,Na₃Sc₂(PO₄)₃∶0.06Tm³⁺,yDy³⁺荧光粉的发光颜色由蓝色转变为白色,再由白色变黄色。 Na₃Sc₂(PO₄)₃∶Tm³⁺,Dy³⁺荧光粉作为一种可调色或单相白光荧光粉在发光二极管上具有潜在的应用前景。     

La_(2.4)Mo_(1.6)O_8∶Yb~(3+),Er~(3+)材料的制备及其上转换发光性质

采用高温固相法制备了La_(2.4)Mo_(1.6)O_8∶Yb~(3+),Er~(3+)荧光粉。通过X射线衍射(XRD)和上转换发射光谱对样品进行了相结构和发光性质表征。XRD实验结果表明:合成的样品为面心立方萤石结构(Fm-3m)的La_(2.4)Mo_(1.6)O_8相。在980 nm红外光激发下,La_(2.4)Mo_(1.6)O_8∶Yb~(3+),Er~(3+)荧光粉发出分别来自Er~(3+)离子的~2H1_(1/2)→~4I_(15/2)、~4S_(3/2)→~4I_(15/2)跃迁的绿光(主峰为548和529 nm)和~4F_(9/2)→~4I_(15/2)跃迁的红光(主峰为670 nm)。进一步地,对样品中可能的上转换发光机制进行了讨论。     

Yb ion as a sensitizer for the upconversion luminescence in nanocrystalline Gd3Ga5O12:Ho

The effect of Yb³⁺ co-doping on the upconversion luminescence in nanocrystalline Gd₃Ga₅O₁₂:Ho³⁺ was examined. Strong and efficient NIR to green anti-Stokes luminescence was noted in nanocrystalline Gd₃Ga₅O₁₂:Ho³⁺, Yb³⁺ after excitation into the ²F_5/2 level of Yb³⁺ with 978 nm radiation. Weaker blue, red and NIR anti-Stokes luminescence was also observed after 978 nm excitation. An enhancement of the red ⁵F₅ → ⁵I₈ luminescence was observed in the anti-Stokes spectrum compared to the Stokes emission spectrum. This enhancement was attributed to two distinct energy transfer upconversion (ETU) mechanisms which preferentially populate the (⁵F₄, ⁵S₂) and ⁵F₅ levels.     

水杨酸盐敏化BaF2∶Tb3+纳米粒子中的Tb3+离子发光

采用水热法制备了均匀、单分散的BaF₂∶Tb³⁺纳米粒子,并采用离子交换法制备了水杨酸钠敏化的BaF₂∶Tb³⁺纳米粒子(SS-BaF₂∶Tb³⁺)。 系统地研究了样品的结构、形貌和光致发光性质。 结果表明,监测Tb³⁺离子在547 nm的⁵D₄→⁷F₅跃迁,SS-BaF₂∶Tb³⁺纳米粒子获得了从200 nm到385 nm波长范围宽的激发带;激发SS的π-π^*电子跃迁吸收,由于SS到Tb³⁺的能量传递(“天线效应”),SS-BaF₂∶Tb³⁺纳米粒子产生了增强的Tb³⁺离子绿光发射;敏化纳米粒子中Tb³⁺离子光致发光寿命比未敏化纳米粒子中Tb³⁺离子寿命长。     

Preparation and Luminescence Properties of Color-tunable Single-phased LaPO4: Eu3+/Tb3+ Phosphors

A novel series of color-tunable single-phased phosphors La_1-x-yPO₄:xEu³⁺/yTb³⁺(x=0, 0.01, 0.02, 0.03, 0.04, 0.05; y=0, 0.05, 0.10, 0.15, 0.20) was synthesized via microwave-assisted co-precipitation method with diammonium hydrogen phosphate as precipitant. The morphology, crystal structure and photoluminescence properties of the as-prepared samples were characterized by means of X-ray diffraction(XRD), scanning electron microscopy(SEM) and fluorescence spectrophotometer. The results reveal that the as-synthesized samples calcined at 1100℃ display spherical morphology with uniform distribution. Upon excitation with 350 nm ultraviolet radiation, the LaPO₄:Eu³⁺/Tb³⁺ phosphors showed a green light peaking at 543 nm assigned to the characteristic ⁵D₄-⁷F₅ emission of Tb³⁺ and a red light peaking at 591 nm corresponding to the characteristic ⁵D₀-⁷F₁ emission of Eu³⁺ simultaneously. For the Eu³⁺/Tb³⁺ co-activated phosphors, Tb³⁺ acts as an efficient sensitizer to enhance the emission intensity of Eu³⁺ ions. The energy transfer mechanism and the emission color tunability of LaPO₄:Eu³⁺/Tb³⁺ have been studied. The results indicate that a color-tunable luminescence(from green to white to red) can be achieved by adjusting the Eu³⁺/Tb³⁺ doping ratio in the LaPO₄ host matrix.