Tb~(3 )在MO(M=Ca,Sr)中的长余辉发光

长余辉发光材料的研究与应用,已有近100年的历史,目前仍在许多领域中有着重要应用[1].此类材料与其他光致发光材料具有相同的发光性能,只是更注重其发光的衰减过程和热释光性能.如,ZnS:Cu作为黄绿色的长余辉发光材料,在1992年以前是余辉性能最好的长余辉发光材料,一直处于发光研究工作的中心.     

SrAl2O4∶Eu2+，Dy3+长余辉材料发光性能与温度依赖研究

对SrAl₂O₄∶Eu²⁺,Dy³⁺长余辉材料在100~500 K温度之间的发光性能进行研究。实验结果表明,材料的荧光及余辉强度在特定温度区间内呈线性变化,在热释峰所在温度范围具有较好的发光性能。其变化规律表明SrAl₂O₄∶Eu²⁺,Dy³⁺长余辉材料内部陷阱中电子的释放包括瞬时释放和延时释放两种类型,其中电子瞬时释放进而跃迁发光是荧光的组成部分,延时释放产生的跃迁则导致余辉发光。陷阱和电子的复合与陷阱中电子释放过程均随温度升高而增强,但温度过高时会发生热猝灭。材料荧光强度与余辉强度在特定温度区间内随温度呈线性变化关系表明其可以作为一种光纤温度传感材料。     

基于Eu~(2+)与Sm~(3+)的几种新型多色长余辉材料

长余辉发光材料因其节能环保的特点备受人们关注,目前能够满足实际应用的只有绿色长余辉发光材料,严重缺乏具备一定性能的红、黄色等长波长发射的长余辉发光材料。此外,长余辉发光机制尚未取得共识,所提出的相关机制模型均具有一定的局限性,无法为长余辉发光材料的开发和研究提供有力的理论指导。针对上述问题,主要介绍了近期研制的几种不同余辉颜色的新型长余辉材料,并根据材料发光、余辉等特性对余辉机制进行了探讨。     

长余辉发光材料研究进展

90年代发现和发展起来的铝酸盐体系长余辉发光材料是一类重要的新 型能源材料和节能材料。本文主要综述了最近几年来铝酸盐体系中长人科辉发光研究进展。指出了氧化物体系长余辉发光材料的特点和优势,总结了新型长余辉发光材料的基质和激活剂种类、性质及其对稀土 离子 长余辉发光性能的影响和作用,概括了长余辉发光模型,并提出了今后研究和应用的发展方向。     

基于过渡金属离子Mn~(4+),Cr~(3+)的长波长余辉发光材料的研究进展

区别于稀土离子掺杂长波长余辉发光材料,过渡金属离子掺杂长波(600～1300 nm)长余辉发光材料因其稳定高效的宽带发光被应用于生物成像和药物输送等领域,特别是在生物成像领域被广泛研究。近年来,这一领域的基础研究和应用探索取得了长足的进步,但余辉性能仍然有待提高。主要以发光中心离子为线索总结了近年来报道的过渡金属离子掺杂长波长余辉发光材料,讨论了其余辉性能的优化途径,并介绍了过渡金属离子掺杂长波长余辉发光纳米探针在生物医学领域的应用。最后,对目前相关研究的发展前景进行了展望。     

稀土红色长余辉发光材料研究进展

综述了稀土元素掺杂红色长余辉发光材料的研究进展，总结了硫化物、钛酸盐、硫氧化物、硅酸盐、氧化物和磷酸盐等基质体系的红色长余辉发光，并指出硫氧化物和磷酸盐等基质是最具有发展前景的红色长余辉发光体系，讨论了Eu^2 在硫化物、Pr^3 在钛酸盐以及Eu^3 和Sm^3 等稀土离子在硫氧化物和硅酸盐等体系中的红色长余辉发光机制。介绍了传统的高温固相法以及溶胶．凝胶法、微波合成法等稀土红色长余辉材料的制备技术。提出了从基质材料、制备技术和稀土离子发光机制入手是稀土红色长余辉发光材料今后研究与开发的发展方向。     

一种新的橙红色长余辉荧光材料Y2O2S∶Sm3+

铜激活的硫化锌(ZnS∶Cu)和铕激活的硫化钙(CaS∶Eu)是最早获得应用的蓝色和红色长余辉材料. 随后, 相继发现了铝酸盐体系和硅酸盐体系两大类长余辉荧光材料[1～3]. 这两类长余辉荧光材料在发光亮度、余辉时间、稳定性方面都较前述硫化物系列长余辉荧光材料有很大提高, 从而具有非常广阔的应用前景和应用范围[4～6]. 但这两类长余辉荧光材料的发光颜色一般为蓝紫、蓝或黄绿, 没有红色发光现象. 随着研究的深入, 人们发现了稀土元素激活的碱土钛酸盐红色长余辉荧光材料, 这种荧光材料在发光亮度及余辉上都有明显的提高[7,8], 而且解决了硫化物不稳定的缺点. 近年来才发展起来的以碱土金属氧化物为发光基质, 以Eu3+为激活剂的红色长余辉荧光材料进一步提高了余辉亮度及时间[9].     

长余辉发光材料在陶瓷行业的应用研究

长余辉发光材料和陶／搪瓷材料的结合始于80年代,当时采用的是传统的硫化物体系长余辉发光材料。20世纪90年代,随着多种新型长余辉材料的发现,使性能更佳的长余辉陶／搪瓷制品的开发成为可能。本文介绍新型铝酸盐体系、硅酸盐体系及新型红色长余辉材料应用于低温陶／搪瓷釉料（800－900℃）、中温陶瓷釉料（980－1100℃）,及将低温陶／搪瓷釉料、中温陶瓷釉料应用于陶／搪瓷制品的研究,以及将各种新型长余辉材料应用于花纸、玻璃行业中。这种长余辉陶／瓷制品性能稳定、发光强度达到发光粉的80％,发光时间可达12h以上;而且应用工艺简单,可直接用传统的陶／搪瓷制品工艺进行生产。     

蓝色长余辉材料CaAl2O4:Eu2+,Nd3+的合成及其发光性能

采用高温固相法合成了系列单相Ca(1-x-y)Al2O4:Eu2+x,Nd3+y(0≤x≤0.045,0≤y≤0.0037)粉末样品,并表征了其发光特性.研究结果表明,样品的发射光谱为最大发射峰位于440nm的宽带谱,属于Eu2+的4f65d→4f7跃迁.通过对Eu2+,Nd3+掺杂量与样品发光性能之间关系的研究发现,Eu2+和Nd3+最佳掺杂量分别为x=0.00125和y=0.0025,并且Nd3+对改善蓝色长余辉材料CaAl4:Eu2+的余辉性能具有重要的作用.在最佳掺杂条件下,样品的余辉时间可达1000min,初始亮度大于1200mcd/m2,60min后发光粉的亮度仍然在10mcd/m2以上.利用正电子湮灭技术和热释光技术,研究了Eu2+和Nd3+对CaAl2O4:Eu2+,Nd3+材料的发光性能的影响.     

新型红色荧光粉Sr3Al2O6的合成和发光性能研究

稀土金属离子激活的多铝酸盐发光材料，在可见光区具有较高的量子效率犤１～４犦，充分显示出这类荧光发光材料，在高效节能、环保、电光源与新一代可见光显示器领域的应用前景犤４～９犦。特别是SrAl２O４∶Eu２＋的持续发光现象的发现犤２，３犦，激起了对以稀土金属离子为激活剂，碱土铝酸盐为基质的长余辉无机发光材料体系的兴趣。研究表明其发光强度和余辉时间是传统硫化物发光材料的十倍以上，利用其长余辉储光－发光特性，有望开发新型发光油漆、涂料、发光陶瓷、发光塑料、薄膜、发光纸、发光纤维犤４犦。早在七十年代，荷兰菲利…     

ZnO-B2O3∶Tb3+长余辉玻璃的发光性质

通过还原方法制备了Tb³⁺离子掺杂的硼酸锌玻璃，并观察到在254 nm紫外光激发后有明亮的绿色长余辉发光现象，余辉时间达6 h。通过激发与发射光谱、余辉光谱、余辉衰减曲线、热释光谱、热释光释出速率衰减曲线等得到的信息，研究了Tb³⁺离子掺杂的硼酸锌玻璃的发光性质。     

M5(PO4)3F (M=Ca, Sr, Ba)中Sm3+的电荷迁移态及Sm3+和Eu3+的电荷迁移能量关系

采用高温固相反应合成了M_5-2xSm_xNa_x(PO₄)₃F(M=Ca,Sr,Ba)荧光体,研究了其在真空紫外-可见光范围的发光特性。发现在Ca₅(PO₄)₃F中Sm³⁺的电荷迁移带约在191 nm,在Sr₅(PO₄)₃F中约在199 nm,而在Ba₅(PO₄)₃F中约在204 nm,随着被取代碱土离子半径的增大电荷迁移能量逐渐减小。比较了M₅(PO₄)₃F (M=Ca,Sr,Ba)中Sm³⁺和Eu³⁺电荷迁移能量的关系。     

Inter-conversion of Tb3+ and Tb4+ states and its fluorescence properties in MO–Al2O3: Tb (M = Mg,Ca, Sr,Ba) phosphor materials

Terbium ion doped MO–Al₂O₃ (M = Mg, Ca, Sr and Ba) series phosphors have been synthesized through combustion technique and their luminescence properties have been studied and compared. Terbium ion in different phosphors has shown different fluorescence properties due to the presence of different ratios of Tb³⁺ and Tb⁴⁺ states in different samples. The UV/Visible absorption and XPS techniques have been used to probe the existence of Tb³⁺ and Tb⁴⁺ states. The host sensitive 4f–5d and the charge transfer transitions enabled the use of terbium ion as an indicator of the structure.     

NaBaPOM4:Tb3+绿色荧光粉制备及其发光特性

采用高温固相法合成了NaBaPOM₄:Tb³⁺绿色荧光粉, 并研究了材料的发光性质. NaBaPOM₄:Tb³⁺材料呈多峰发射, 发射峰位于437、490、543、587和624 nm, 分别对应Tb³⁺的⁵D₃→⁷F₄和⁵D₄→⁷F_{J=6, 5, 4, 3}跃迁发射, 主峰为543 nm; 监测543 nm发射峰, 所得激发光谱由4f⁷5d¹宽带吸收(200-330 nm)和4f-4f 电子吸收(330-400 nm)组成, 主峰为380 nm. 研究了Tb³⁺掺杂浓度, 电荷补偿剂Li⁺、Na⁺、K⁺和Cl^-, 及敏化剂Ce³⁺对NaBaPOM₄:Tb³⁺材料发射强度的影响. 结果显示: 调节激活剂浓度、添加电荷补偿剂或敏化剂均可以在很大程度上提高材料的发射强度.     

Bright Infrared-to-Ultraviolet/Visible Upconversion in Small Alkaline Earth-Based Nanoparticles with Biocompatible CaF2 Shells

Upconverting nanoparticles (UCNPs) are promising candidates for photon-driven reactions, including light-triggered drug delivery, photodynamic therapy, and photocatalysis. Herein, we investigate the NIR-to-UV/visible emission of sub-15 nm alkaline-earth rare-earth fluoride UCNPs (M_1−xLn_xF_2+x, MLnF) with a CaF₂ shell. We synthesize 8 alkaline-earth host materials doped with Yb³⁺ and Tm³⁺, with alkaline-earth (M) spanning Ca, Sr, and Ba, MgSr, CaSr, CaBa, SrBa, and CaSrBa. We explore UCNP composition, size, and lanthanide doping-dependent emission, focusing on upconversion quantum yield (UCQY) and UV emission. UCQY values of 2.46 % at 250 W cm⁻² are achieved with 14.5 nm SrLuF@CaF₂ particles, with 7.3 % of total emission in the UV. In 10.9 nm SrYbF:1 %Tm³⁺@CaF₂ particles, UV emission increased to 9.9 % with UCQY at 1.14 %. We demonstrate dye degradation under NIR illumination using SrYbF:1 %Tm³⁺@CaF₂, highlighting the efficiency of these UCNPs and their ability to trigger photoprocesses.     

Terbium sensitized luminescence for the determination of fexofenadine in pharmaceutical formulations

A sensitive and specific luminescence method for the determination of Fexofenadine (FEX), in pharmaceutical formulations is reported. The method is based on the sensitization of terbium (Tb³⁺) by complex formation with FEX. The luminescence signal for Tb–FEX complex is greatly enhanced by the addition of triethylamine (ET₃N) and zinc nitrate in methanol solution. Monitoring of the signal is accomplished when the instrument is in the phosphorescence mode with the excitation and emission wavelengths set at λ_ex = 220 nm and λ_em = 550 nm respectively. Optimum conditions for the formation of the complex in methanol were 2.25 × 10^?6 M of Tb³⁺, 5.00 × 10^?6 M of Et₃N and Zn²⁺ which allows for the determination of 10–800 ppb of FEX in the batch mode with a detection limit of 0.3 ppb. The proposed method was successfully applied for the determination of FEX in pharmaceutical formulations.     

A new BaB2Si2O8:Eu/Eu, Tb phosphor - Synthesis and photoluminescence properties

In the present work, we have synthesized maleevite mineral phase BaB₂Si₂O₈ for the first time, which is isostructural with the pekovite mineral SrB₂Si₂O₈. In these europium doped host lattices, we observed the partial reduction of Eu³⁺ to Eu²⁺ at high temperature during the synthesis in air. Tb³⁺ co-doping in MB₂Si₂O₈:0.01(Eu³⁺/Eu²⁺) [M=Sr, Ba] improves the emission properties towards white light. The emission color varies from bluish white to greenish white under UV lamp excitation when the host cation changes from Sr to Ba.     

White-light-emitting long-lasting phosphorescence in Dy-doped SrSiO3

We report on a luminescent phenomenon in Dy³⁺-doped SrSiO₃ long-lasting phosphor. After irradiation by a 254-nm UV lamp for 5 min, the Dy³⁺-doped SrSiO₃ phosphor emits white light-emitting long-lasting phosphorescence for more than 1 h even after the irradiation source has been removed. Photoluminescence, long-lasting phosphorescence and thermoluminescence (TL) spectra are used to explain this phenomenon. Photoluminescence spectra reveal that the white light-emitting long-lasting phosphorescence originated from the two mixtures of Dy³⁺ characteristic luminescence, the 480-nm blue emission (⁴F_9/2→⁶H_15/2) and the 572-nm yellow emission (⁴F_9/2→⁶H_13/2). TL spectra shows that the introduction of Dy³⁺ ions into the SrSiO₃ host produces a highly dense trapping level at 377 K (0.59 eV), which is responsible for the long-lasting phosphorescence at room temperature. A possible mechanism of the long-lasting phosphorescence based on the experimental results is proposed. It is considered that the long-lasting phosphorescence is due to persistent energy transfer from the electron traps to the Dy³⁺ ions, which creates the persistent luminescence of Dy³⁺ to produce the white light-emitting long-lasting phosphorescence.     

Facile and Controllable Synthesis of Monodisperse CaF2 and CaF2:Ce3+/Tb3+ Hollow Spheres as Efficient Luminescent Materials and Smart Drug Carriers

Highly uniform and well‐dispersed CaF₂ hollow spheres with tunable particle size (300–930 nm) have been synthesized by a facile hydrothermal process. Their shells are composed of numerous nanocrystals (about 40 nm in diameter). The morphology and size of the CaF₂ products are strongly dependent on experimental parameters such as reaction time, pH value, and organic additives. The size of the CaF₂ hollow spheres can be controlled from 300 to 930 nm by adjusting the pH value. Nitrogen adsorption–desorption measurements suggest that mesopores (av 24.6 nm) exist in these hollow spheres. In addition, Ce³⁺/Tb³⁺‐codoped CaF₂ hollow spheres can be prepared similarly, and show efficient energy transfer from Ce³⁺ to Tb³⁺ and strong green photoluminescence of Tb³⁺ (541 nm, ⁵D₄→⁷F₅ transition of Tb³⁺, the highest quantum efficiency reaches 77 %). The monodisperse CaF₂:Ce³⁺/Tb³⁺ hollow spheres also have desirable properties as drug carriers. Ibuprofen‐loaded CaF₂:Ce³⁺/Tb³⁺ samples still show green luminescence of Tb³⁺ under UV irradiation, and the emission intensity of Tb³⁺ in the drug‐carrier system varies with the released amount of ibuprofen, so that drug release can be easily tracked and monitored by means of the change in luminescence intensity. The formation mechanism and luminescent and drug‐release properties were studied in detail.     

Photoluminescence properties of La(PO3)3:Tb under VUV excitation

La_1−x(PO₃)₃:Tb_x³⁺ (0<x0.6) were prepared using solid-state reaction. The vacuum ultraviolet (VUV) excitation spectrum of La_0.55(PO₃)₃:Tb_0.45³⁺ indicates that the absorption of (PO₃)₃³⁻ groups locates at about 163 and 174 nm and the absorption bands of (PO₃)₃³⁻ groups (174 nm) and La³⁺–O²⁻ (200 nm) and Tb³⁺ (213 nm) overlap each other. These results imply that the (PO₃)₃³⁻ groups can efficiently absorb the excited energy around 172 nm and transfer the energy to Tb³⁺. Under 172 nm excitation, the optimal photoluminescence (PL) intensity is obtained when Tb concentration reaches 0.45 and is about 71% of commercial phosphor Zn_1.96SiO₄:0.04 Mn²⁺ with chromaticity coordinates of (0.343, 0.578) and the decay time of about 4.47 ms.