货币、身份证件、有价证券及商品的伪造和仿制严重威胁国家政治安全、金融稳定,侵害社会团体及个人利益。防伪技术是防范和抑制造假和克隆行为的有效手段,基于发光材料的防伪标签是当前防伪领域的研究热点。本文主要介绍近年来用于防伪标签的发光材料的研究进展,包括用于防伪标签发光材料的种类、防伪材料的发光机理、实现防伪鉴别所使用的激励源、发光防伪标签的设计方法及制作技术和防伪标签的鉴别方法等。此外,本文还对当前发光防伪材料存在的问题,以及未来发展趋势作了系统分析。
1 宁波大学 光电子功能材料重点实验室, 宁波 315211
2 大连海事大学 物理系, 大连 116026
采用改进的坩埚下降法成功生长了Ce 3+/Yb 3+离子双掺杂LiLuF4单晶, Ce 3+的初始离子掺杂浓度为0.1mol%, Yb 3+离子浓度从0变化到2.0mol%。在波长291 nm激发时观察到Yb 3+在1020 nm( 2F5/2→ 2F7/2)附近的强近红外发射以及Ce 3+在300~350 nm(5d→4f)的紫外发射。通过吸收光谱、荧光光谱研究了Yb 3+离子掺杂浓度对Ce 3+/Yb 3+共掺杂LiLuF4单晶光谱性质的影响及Ce 3+到Yb 3+离子的能量转移机理。通过变温光谱的研究发现, 当环境温度从298 K增加到443 K时, 其荧光发射强度不断降低。Ce 3+/Yb 3+共掺杂LiLuF4单晶发光波长主要位于紫外和近红外, 这种独特的发光属性可望用于防伪技术和公共安全事务中。
Ce
3+/Yb
3+ 紫外和近红外发射 LiLuF4单晶 能量转移 Ce
3+ and Yb
3+ ultraviolet and infrared emissions LiLuF4 single crystal energy transfer
1 宁波大学 光电子材料重点实验室, 浙江 宁波 315211
2 山东大学晶体材料研究所 晶体材料国家重点实验室, 山东 济南 250100
3 大连海事大学 物理系, 辽宁 大连 116026
用坩埚下降法生长了Tm3+掺杂浓度分别为0.8%和1.3%的优质大尺寸LiYF4(LYF)单晶体。测定了单晶体的吸收光谱、发射光谱, 并计算了3F4能级的的最大吸收截面与最大发射截面分别为0.25×10-20 cm2和0.33×10-20 cm2。以796 nm半导体激光器(LD)为泵浦源, 采用短平板腔结构模型研究了Tm掺杂LYF单晶体在~2.0 μm波段的激光输出性能。当LD泵浦功率为3.4 W时, Tm∶YLF晶体的最大激光输出功率为1.88 W, 相应的光光转换效率和斜率效率分别为51%和57%。使用半导体可饱和吸收镜抽运Tm掺杂LYF单晶体, 测试其在~2.0 μm波段连续波锁模激光运转。当最大抽运功率为3.5 W时, 获得锁模激光的最大平均输出功率为200 mW, 此时锁模脉冲宽度~20 ps, 对应的重复频率63.86 MHz, 中心谱线为1.88 μm。结果表明, Tm掺杂LYF单晶体是一种具有较好物理性能的~2 μm波段超快激光晶体。
Tm离子 连续波 连续波锁模 thulium ion 2.0 μm 2.0 μm continuous-wave(CW) continuous-wave(CW) mode-locked
Author Affiliations
Abstract
1 Key Laboratory of Photo-Electronic Materials, Ningbo University, Ningbo 315211, China
2 State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering and College of Physics, Jilin University, Changchun 130012, China
3 Department of Physics, Dalian Maritime University, Dalian 116026, China
Yb3+/Er3+ co-doped Na5Lu9F32 single crystals used as a spectral up-converter to improve the power conversion efficiency of perovskite solar cells are prepared via an improved Bridgman approach. Green and red up-conversion (UC) emissions under the excitation of near-infrared (NIR) bands of 900–1000 nm and 1400–1600 nm can be observed. The effectiveness of the prepared materials as a spectral converter is verified by the enhancement of power conversion efficiency of perovskite solar cells. The sample with a UC layer is 15.5% more efficient in converting sunlight to electricity compared to the UC layer-free sample due to the absorption of sunlight in the NIR range. The results suggest the synthesized Yb3+/Er3+ co-doped Na5Lu9F32 single crystals are suitable for enhancing the performance of perovskite solar cells.
160.4670 Optical materials 260.1180 Crystal optics 260.2510 Fluorescence 350.6050 Solar energy Chinese Optics Letters
2019, 17(9): 091601
1 宁波大学 光电子功能材料重点实验室, 浙江 宁波 315211
2 大连海事大学 物理系, 辽宁 大连 116026
应用坩埚下降法生长了Pr3+离子掺杂的Na5Lu9F32单晶体.系统地研究了Pr3+掺杂的Na5Lu9F32单晶的吸收光谱、荧光光谱和荧光衰减曲线.应用Judd-Ofelt理论分析计算了其光学强度等参数, 结果表明Pr3+离子处于Pr-F强共价键的高对称环境中.在440 nm光的激发下观察到以482、523和605 nm为中心的尖锐的强荧光发射带.研究了Pr3+掺杂浓度对上述发光强度的影响规律, 实验发现当Pr3+掺杂浓度达到~0.5 mol%时, 其荧光发射强度达到最大.分析了环境温度从298 K到443 K变化时对荧光强度的影响, 随着温度的增加, 荧光强度逐步变弱, 且其523 nm的绿光受温度影响要小于482 nm的蓝光和605 nm的红光.
光学材料 Na5Lu9F32单晶体 变温 能量传递 光学性能 Optical materials Na5Lu9F32 single crystals Temperature dependent Energy transfer Optical properties
Author Affiliations
Abstract
1 Key Laboratory of Photo-Electronic Materials, Ningbo University, Ningbo 315211, China
2 College of Physics and Electronic Engineering, College of Chemistry and Pharmaceutical Engineering, Nanyang Normal University, Nanyang 473061, China
3 Department of Physics, Dalian Maritime University, Dalian 116026, China
A 0.1 mol.% CoF2-doped Na5Lu9F32 single crystal with high quality in the size of ~ 10 mm×100 mm was grown by the Bridgman method. Three peaks located at 504, 544, and 688 nm and a broad band in the range of 1200–1600 nm centered at 1472 nm were observed in the absorption spectra. The absorption peak position suggests cobalt ions in the divalent state in the grown crystal. Moreover, the cobalt ions are confirmed to locate in the distorted cubic crystal structure. Upon excitation of 500 nm light, a sharp emission peak at 747 nm ascribed to the T22(H1)→4A2(F) transition was observed for the crystal. The Co2+-doped Na5Lu9F32 crystal shows a potentially promising material for the application of a passively Q-switched laser operating in the near-infrared range.
160.4670 Optical materials 140.3380 Laser materials Chinese Optics Letters
2018, 16(6): 061601
1 宁波大学 光电子功能材料重点实验室, 浙江 宁波 315211
2 大连海事大学 物理系, 辽宁 大连 116026
采用改进过的布里奇曼法成功地生长了Tm3+离子浓度从0.5~4 mol%变化的高质量Na5Lu9F32单晶.在790 nm LD激发下, 研究了不同Tm3+掺杂晶体在1.86 μm波段的荧光发射性能、衰减曲线以及Tm3+离子之间的能量传递过程.当Tm3+离子掺杂浓度增加到~1.95 mol%时, 晶体在1.86 μm处的荧光发射强度达到最大.然后, 随着Tm3+离子浓度进一步的增大, 发射强度迅速下降.然而, Tm3+离子在3F4能级处的荧光寿命随着Tm3+掺杂浓度从0.5增加到4 mol%, 逐渐降低.同时计算了1.86 μm处最大的受激发射截面为0.80×10-20 cm2.Tm3+离子的浓度猝灭效应和离子之间的交叉弛豫能量传递过程是造成1.86 μm荧光发射变化的主要原因.
Tm3+离子 Na5Lu9F32单晶 1.8 μm发射 布里奇曼法 交叉弛豫过程 Tm3+ ion Na5Lu9F32 single crystal 1.8 μm emission Bridgman method Cross relaxation process
采用均匀沉淀法,通过改变稀土离子与尿素的量比成功合成了粒径分别为80,55,40 nm的Y2O3∶Eu3+纳米球样品。通过X射线衍射(XRD)、场发射扫描电镜(FE-SEM)和发光光谱对不同尺寸纳米球的晶体结构、微观形貌和发光性质做了分析,对Y2O3∶Eu3+纳米球的生长过程进行了研究。根据Judd-Ofelt理论,利用Eu3+的发射光谱和荧光衰减等数据,计算了5D0→7FJ能级的辐射跃迁速率和荧光分支比,计算得到Y2O3基质材料的折射率为1.80以及不同粒径样品的光学跃迁强度参数。最后分析了5D0能级荧光发射与温度之间的依赖关系,结果证明了荧光温度猝灭行为符合Crossover过程,并通过阿伦尼乌斯公式非线性拟合获得了激活能,粒径为80,55,40 nm的Y2O3∶Eu3+纳米球样品的活化能分别为0.201,0.193,0.200 eV。
Y2O3∶Eu3+纳米球 发光性质 Judd-Ofelt理论 Y2O3∶Eu3+ nanoparticles luminescence properties Judd-Ofelt theory
Author Affiliations
Abstract
1 Key Laboratory of Photoelectronic Materials, Ningbo University, Ningbo 315211, China
2 Ningbo Institute of Materials Technology and Engineering, the Chinese Academy of Sciences, Ningbo 315211, China
3 Department of Physics, Dalian Maritime University, Dalian 116026, China
A Ce3+ ion-doped α-NaYF4 single crystal of high quality is grown successfully by an improved flux Bridgman method under the conditions of taking the chemical raw composition of NaF:KF:YF3:CeF3 in the molar ratio of 30∶18∶48∶4, where the KF is shown to be an effective assistant flux. The x ray diffraction, absorption spectra, excitation spectra, and emission spectra of the Ce3+-doped α-NaYF4 single crystal are measured to investigate the phase and optical properties of the single crystals. The absorption spectrum of the Ce3+:α-NaYF4 shows a strong band that peaks at the wavelength of 300 nm. The emission spectrum of the Ce3+:α-NaYF4 emits an intense ultraviolet (UV) band at the wavelength of 332 nm under the excitation of 300 nm light. Two separated luminous bands of 330 and 350 nm, which correspond to the transitions 5d→F5/22 and 5<
160.0160 Materials 230.0230 Optical devices 260.1180 Crystal optics 300.0300 Spectroscopy Chinese Optics Letters
2016, 14(6): 061601