Mn^(2+)掺杂对YAG∶Ce^(3+)荧光陶瓷发光性能的影响

过渡族金属Mn^(2+)掺杂的石榴石荧光陶瓷被认为是实现高显色激光照明的候选材料。然而,由于Mn^(2+)在不同配位环境下离子半径的多样性,Mn^(2+)掺杂石榴石陶瓷体系设计方案尚不明确。本文采用真空烧结技术制备得到不同浓度Mn^(2+)掺杂的YAG∶Ce^(3+)荧光陶瓷,并将Mn^(2+)分别设计进入八面体(OC)和十二面体(DO)格位。通过表征样品物相和显微结构、光致发光、荧光寿命、量子效率等,并通过LD激光器激发对荧光陶瓷的发光性能进行研究。实验结果表明,在添加电荷与体积补偿剂SiO_(2)的前提下,相比Mn^(2+)进入十二面体格位,Mn^(2+)进入八面体后石榴石的晶体结构更加稳定。因此,当Mn^(2+)的浓度控制在0.5%^(6)%(at)范围内,OC系列样品的量子效率高于DO系列样品。此外,OC系列样品的PL谱中位于588 nm和725 nm处的发射峰分别对应于Mn^(2+)占据八面体和十二面体格位的^(4)T_(1)→^(6)A_(1)电子跃迁,而DO系列样品中位于572 nm处的发射峰则源于Mn^(2+)占据扭曲的十二面体格位产生的电子跃迁。得益于Ce^(3+)→Mn^(2+)间高效的能量传递,将浓度为6%(at)的Mn^(2+)设计进入YAG∶Ce^(3+)中八面体格位制得荧光陶瓷,封装得到的激光白光光源的显色指数为70.8,相对色温为5117 K。本文对于Mn^(2+)掺杂的石榴石发光材料的开发研究是有力补充,也为提升YAG∶Ce^(3+)荧光陶瓷光谱中的红光成分,进而提高医疗、显示等领域的激光光源的显色性能提供借鉴。

Continuous wave and active Q-switched operation of Watt-level LED-pumped two-rod Nd,Ce:YAG laser

A high-performance LED-side-pumped two-rod Nd,Ce:YAG laser with continuous-wave(CW) and acousto–optical(A-O) Q-switched operation is demonstrated in this work. A symmetrically shaped flat–flat cavity with two identical LEDside-pumped laser modules is employed for power scalability. In the CW regime, the maximum output average power of laser at 1064 nm is 4.41 W, corresponding to a maximum optical conversion efficiency of 5.3% and a slope efficiency is 12.4%. In the active Q-switched regime, the pulse energy of laser reaches as high as 0.89 m J at a repetition rate of 800 Hz with a pulse width of 457.2 ns, the corresponding highest peak output power is 1.94 k W and the M~2 factor is measured to be about 8.8. To the best of the authors' knowledge, this is the first demonstration and the highest performance of a CW LED-side-pumped two-rod laser Nd,Ce:YAG with Watt-level output reported so far.

激光照明用YAG∶Ce-CaF_(2)荧光陶瓷的冷烧结制备

荧光陶瓷是激光照明的关键材料。为探究低温制备荧光陶瓷的可行性,采用冷烧结工艺在425℃成功制备了致密度高、晶粒尺寸均匀、相界分明的YAG∶Ce-CaF_(2)复合荧光陶瓷。结果表明:发光相与基体之间没有可检测到的界面反应;制备的荧光陶瓷具有较高的量子效率(74.3%)、较好的热导率(室温可达9.4 W·m^(-1)·K^(-1))、优异的热稳定性(在400 K时发光强度仅损失4.3%);在蓝光激光(451 nm)激发下,复合荧光陶瓷表现出良好的黄光发射,并展现出光通量为910.7 lm和流明效率为91.07 lm·W^(-1)的高亮度白色激光照明,其荧光寿命无衰减(66 ns),相关色温为4483~8247 K,显色指数为73.4~83.6。冷烧结工艺是低温条件下制备性能优良荧光陶瓷的新方法。

高亮度固态照明用LuYAG∶Ce荧光陶瓷

实现高发光效率、高亮度和良好的热稳定性是固态照明的迫切要求。因此,用于高功率发光二极管或激光二极管(LED/LD)的高性能荧光转换材料具有重要的研究意义。在这项工作中,通过将Lu^(3+)离子引入YAG∶Ce荧光陶瓷中方法作为有效策略来改善YAG∶Ce荧光材料的发光性能。采用固相反应和真空烧结法制Article ID:1000-7032(2023)06-0964^(-1)1收稿日期:2022^(-1)2-31;修订日期:2023-01-30基金项目:中国科学院战略性先导科技专项(XDA22010301)Supported by The Strategic Priority Research Program of The Chinese Academy of Sciences(XDA22010301)第6 HUANG Xinyou期,et al.:LuYAG∶Ce Transparent Ceramic Phosphors for High-brightness Solid-state…备了不同Lu^(3+)含量的(Lu,Y)_(3)Al_(5)O_(12)∶Ce荧光陶瓷(LuYAG∶Ce荧光陶瓷)。随着Lu^(3+)含量的增加,LuYAG∶Ce荧光陶瓷中的Y^(3+)位点被Lu^(3+)位点取代,Ce^(3+)的发射峰呈现从573 nm到563 nm的蓝移现象。当Lu^(3+)含量为60%时,通过将LuYAG∶Ce荧光陶瓷与蓝光LED组合,其发光强度达到最大值,流明效率达到114 lm∙W^(-1)。使用450 nm激光源与LuYAG∶Ce荧光陶瓷构建了透射模式下的激光驱动照明装置。随着功率密度从2.2 W·mm^(-2)增加到39 W·mm^(-2),Lu^(3+)含量为60%的荧光陶瓷光通量从128 lm增加到1874 lm,且没有发光饱和的迹象,最佳发光效率达到128 lm·W^(-1)。因此,LuYAG∶Ce荧光陶瓷有望成为高功率LED/LD照明的潜在荧光转换材料。

NaYSiO_(4)∶Ce^(3+)蓝色荧光粉的发光性质及其在白光发光二极管上的应用

采用高温固相法合成了NaYSiO_(4)∶xCe^(3+)(0.01≤x≤0.05)系列蓝色荧光粉。NaYSiO_(4)∶xCe^(3+)荧光粉在250~360 nm之间的宽带吸收能与紫外LED芯片很好地匹配。NaYSiO_(4)∶xCe^(3+)荧光粉中存在多个Ce^(3+)离子荧光中心,且在紫外光激发下表现出峰值波长位于414 nm附近的宽带蓝光发射。NaYSiO_(4)∶0.02Ce^(3+)荧光粉在300~350 nm紫外光激发下量子效率在25%以上。NaYSiO_(4)∶0.02Ce^(3+)荧光粉表现出优良的化学稳定性,在水中浸泡14 d后荧光强度和量子效率几乎不变。将NaYSiO_(4)∶0.02Ce^(3+)蓝色荧光粉、商用(Sr,Ba)_2SiO_(4)∶Eu^(2+)绿色荧光粉和商用(Ca,Sr)AlSiN_(3)∶Eu^(2+)红色荧光粉涂覆于310 nm紫外LED芯片上制备得到了显色指数高达95的LED器件。当驱动电流从50 mA逐渐增大到300 mA时,制备的LED器件表现出稳定的暖白光发射,其色坐标几乎不变。上述结果说明,本研究报道的NaYSiO_(4)∶0.02Ce^(3+)蓝色荧光粉在紫外LED芯片驱动的白光发光二极管照明上有着潜在应用价值。

YAG∶Ce Phosphors for WLED via Nano-Pesudoboehmite Sol-Gel Route

The sub-micron sized YAG ： Ce phosphors were synthesized via a modified sol-gel method by peptizing nano-pesudoboehmite particulate. It is found that YAG phase from the dried gel powders appears at 1000 ℃ then the pure YAG phase exists at a relatively lower sintering temperature of 1400 ℃. The smaller sizes of phosphors in the ranges of 1 - 3 μm are obtained due to the contribution of seeding effects of nano-sized alumina particles to strengthen each step of the processes. Both the excitation and emission spectra of photoluminescence of the phosphor obtained at 1400 ℃ meet well with the spectroscopic requirements of the WLED phosphors.

Synthesis of Ce:YAG Phosphor via Homogeneous Precipitation under Microwave Irradiation

Ultra-fine Ce:YAG phosphors were prepared by homogeneous precipitation under microwave irradiation method . The formation of Ce: YAG was investigated by means of XRD and DTA/TG. The purified YAG crystallized phase was obtained at a lower temperature (1100℃). Basically spherical Ce:YAG powders were indicated from TEM images, and the size of the particles is about 80 nm. Two peaks of 436 and 473 nm can be seen from the excitation spectrum in the range of 402 -510 nm. A broad emission band located at 480 ~ 630 nm shows the phosphors prepared by this method have good emission properties.

Synthesis of YAG∶Ce^(3+) Phosphor by Polyacrylamide Gel Method and Promoting Action of α-Al_2O_3 Seed Crystal on Phase Formation

YAG： Ce^3 ＋ phosphor particles were prepared using polyacrylamide gel method. The structure evolution of powders during annealing process was followed by X-ray diffraction determination. It is found that some intermediate phases, including θ-Al2O3, YAM and YAP, are formed when calcining polyacrylamide gel, however, the pure YAG phase can be formed directly when calcining polyacrylamide gel with α-Al2O3 as seed crystal. These facts show that the existence of α- Al2O3 seed crystal can block the formation of θ-Al2O3, YAM and YAP, and accelerate its reaction with Y2O3 to form YAG phase directly at lower temperature. The emission peak of prepared YAG ： Ce^3 ＋ phosphor is wide with maximum at 550 nm and the exitation band has two peaks, the major one is around at 460 nm, which matches the blue emission of GaN LED and is suitable for the assemble of white LED. Some fluxes can enhance the photoluminescence intensity of phosphor particles, that can be attributed both to the improvement of crystallization processes of YAG and to the stabilization of trivalence cerium ion in YAG：Ce^3 ＋.

Spherical YAG∶Ce^(3+) Phosphor Particles Prepared by Spray Pyrolysis

Spherical YAG：Ce^3＋ phosphor particles with narrow size distribution were prepared by spray pyrolysis. The effects of the concentration of solution, the flow rate of cartier gas and the annexing temperature on the phosphor morphology were studied. The productivity of precursor particles shows a trend of drop after rising with the increase of concentration Raising the flow rate of nitrogen can improve the productivity of the precursor particles. Phosphor prepared by spray pyrolysis has obviously higher emission intensity than that synthesized by solid state reaction, spray pyrolysis makes Ce^3＋ ions well distributed in the crystal lattice as the luminescent centers, and phosphor particles have regular sphericity and narrow size distribution.

A novel method for the synthesis of YAG:Ce phosphor

YAG:Ce phosphor was synthesized by a novel simple method,wherein the admixture of three raw materials(Y2O3,α-Al2O3 and CeO2) were first acidified by diluted nitric acid to prepare a precursor,followed by a high temperature heating treatment of the obtained precursor under reductive atmosphere.Through XRD measurement and SEM observation,it was found that Y2O3,one of the raw material,was firstly dissolved into the diluted nitric acid,and then recrystallized on the surface of both α-Al2O3 and CeO2 to form a no...

Spectral Property and Thermal Quenching Behavior of Tb^(3+)-Doped YAG:Ce Phosphor

A series of YAG：Ce,Tb phosphors were synthesized by vacuum sintering method.Moreover,their spectral properties,thermal quenching behaviors and color rendering properties were investigated systematically.The photoluminescence emission spectra of YAG：Ce,Tb show a great red shift compared with that of YAG：Ce.Direct energy transfer from Tb^（3＋） to Ce^（3＋） ions is verified based on the analysis of different photoluminescence spectra.The quenching temperature for Tb^（3＋）-doped YAG：Ce phosphors is about 490 K.The thermal activation energy is estimated to be 0.18 and 0.291 eV for Tb^（3＋）-doped YAG：Ce and YAG：Ce phosphors,respectively.The smaller activation energy for Tb^（3＋）-doped YAG：Ce means a more rapid nonradiative transition from 5d to 4f state,thus resulting in the lower quenching temperature.In addition,white LEDs with improved color rendering properties are achieved by using modified YAG：Ce,Tb phosphors.

Temperature effects on photoluminescence of YAG:Ce^(3+) phosphor and performance in white light-emitting diodes

The well crystalline YAG：Ce^3＋ phosphor was synthesized by sold-state method, and the temperature dependence of excitation and emission spectra of YAG：Ce^3＋ phosphor were investigated in the temperature range from room temperature to 573 K. With temperature increasing, it was noted that the emission intensity of as-repared phosphors decreased considerably more rapidly when pumped by 460 nm than by 340 nm. The temperature-intensity curves under different excitation wavelengths were obtained using an Arrhenius function, and the corresponding activation energies were also obtained respectively. Thus, the experimental phenomenon was discussed in terms of nonradiative decay rate. The effects of as-prepared phosphors on the performance of the white LED with changing temperature were also studied.

放电等离子烧结Ce、Yb共掺钇铝石榴石稀土荧光粉及其在光伏电池中的应用

通过多场耦合实现快速低温烧结的放电等离子技术具有快速、节能和环保等显著优势,在诸多工业领域中得到广泛应用。利用该技术合成Ce^(3+)、Yb^(3+)共掺钇铝石榴石稀土荧光粉,通过物相结构、形态和光谱特性对稀土荧光粉进行综合分析。结果表明,放电等离子烧结工艺有利于Ce^(3+)和Yb^(3+)嵌入钇铝石榴石的晶格中,晶格常数为1.2005 nm。经研磨后的稀土荧光粉颗粒粒径为1~2μm,YAG:Ce^(3+),Yb^(3+)稀土荧光粉的发射光谱峰值为552 nm和720 nm。具有光转换功能的光伏电池的测试结果表明,光伏电池相对外量子响应在500~1000 nm波长范围内有明显改善,同时短路电流密度高达35.95 mA/cm^(2),增益达0.51 mA/cm^(2),光电转换效率相对提高1.91%。

Crystallization, morphology and luminescent properties of YAG:Ce^(3+) phosphor powder prepared by polyacrylamide gel method

A novel synthesis process, based on the polyacrylamide gel method, was used to prepare Ce-doped YAG phosphor powders. Effects of heat treatment parameters, temperature and holding time, the fluxes, and atmosphere on microstructure and particle morphology as well as luminescent properties of YAG:Ce3+ phosphor powders were studied by X-ray powder diffractometry, scanning electron microscopy, and fluorescence spectrophotometry. The results show that the formation temperature (1 000 ℃) of pure YAG phase is significant low when being synthesized by the polyacrylamide gel method, compared with solid-state reaction. For luminescent properties, the intensity of emission of YAG:Ce3+ phosphor increases steadily with increasing temperature from 900 ℃ to 1 300 ℃ and prolonging holding time from 100 min to 400 min. But blue shift phenomenon is observed for 400 min calcination. Fluxes as BaF2 and H3BO3 can enhance the intensity of emission of phosphor due to the improvement of crystallization of YAG and the stabilization of trivalence cerium ion in YAG host lattice at high temperature. Weak reduction atmosphere can contribute to improvement of the emission intensity of YAG:Ce3+ phosphor powders.

Local Structure Mediation and Photoluminescence of Ce^(3+)-and Eu^(3+)-Codoped YAG Nanophosphors

Cerium and europium codoped yttrium aluminum garnet（YAG：Ce,Eu） nanophosphors were prepared by sol-gel method.We systematically explored the structure,composition,morphology and photoluminescence（PL） properties by using X-ray diffraction,scanning electron microscope,high resolution transmission electron microscope,energy dispersive spectrometer,photoluminescence emission and excitation spectra techniques,and focused on clarifying the change of local structure surrounding Ce^3＋ ions by utilizing advanced quantitative ^27Al magic angle spinning nuclear magnetic resonance spectroscopy.The results show that the lattice constant slightly increases as the Ce^3＋ and Eu^3＋ ions incorporate,and the geometric distortion of local structure surrounding Ce^（3＋） activator introduced by the incorporated Eu^（3＋） coactivator causes the variation of crystal field,which results in red shift of Ce^3＋ PL emitting in YAG：Ce,Eu nanophosphor.Furthermore,the YAG：Ce,Eu nanophosphors could exhibit several sharp and narrow ^5D0 → ^7FJ（J = 1-4） emissions of Eu^3＋ ion besides the classic broad ^5d1 → ^4f（^2F（5/2）,^2F（7/2）） emissions of Ce^3＋ ion under near ultraviolet（UV） excitation.

Semi-Quantitative Estimation of Ce³⁺/Ce⁴⁺Ratio in YAG:Ce³⁺Phosphor under Different Sintering Atmosphere

In order to confirm the relationship between the luminescence and the ratio of Ce3+/Ce4+ more clearly, a series of YAG:Ce3+ (Yttrium Aluminum Garnet, Y2.94Al5O12:0.06Ce3+) phosphors were pre- pared under different sintering atmosphere. A semi-quantitative analysis based on X-ray photoe-lectron spectroscopy (XPS) was introduced to study the mole ratio of Ce3+/Ce4+ in the as-synthesized YAG:Ce3+ phosphors. The results indicated that the percentage of Ce3+/(Ce3+ + Ce4+) reached 88.46% under the reduction atmosphere. The emission intensity of YAG:Ce3+ phosphors was in-creased significantly with the increasing of Ce3+ concentration.

YAG∶Ce发光材料合成的助熔剂研究

采用高温固相法合成YAG：Ce荧光粉时，传统的以硼酸为助熔剂的产物硬度很大，处理过程中容易破坏晶体形貌，影响发光性能。采用氟化物助熔剂（MgF2、CaF2、SrF2、BaF2、AlF3）及它们与H3BO3混合助熔剂来制备YAG：Ce，研究了助熔剂种类及其浓度对制得的粉体发光性能的影响，比较了它们的晶体形貌与物相组成。结果表明，采用不同助熔剂合成的YAG：Ce的激发光谱及发射光谱基本相同，而BaF2、AlF3、SrF2及它们与H3BO3的混合助熔剂系列，可在一定程度上降低产品硬度、提高产品发光亮度；其中H3BO3-SrF2系列、H3BO3～BaF2系列的晶化程度与粒度分布均有改善；H3BO3～BaF2系列的物相组成比较纯，除Y3Al5O12：主相外基本无杂相。

白光LED用YAG：Ce^3＋荧光粉的温度猝灭性质

荧光粉的温度猝灭性质是影响白光LED的光效、光色参数和可靠性的关键因素之一。研究了不同激活剂浓度,不同元素掺杂的Y3-xCexAl5O12(YAG∶Ce3+)荧光粉在460nm光激发下的变温亮度和发射光谱。结果表明温度显著影响YAG∶Ce3+荧光粉的发光性能,随着温度的升高,发光强度下降,同时发射光谱红移。Ce含量为0.07(原子数分数)的YAG∶Ce3+荧光粉,150℃下亮度值约为室温时的89%,200℃时的发射光谱相对室温的红移了约10nm。Ce含量的改变对YAG∶Ce3+荧光粉的热猝灭性质影响较小。Lu的掺杂使YAG∶Ce3+荧光粉的发射波长蓝移,同时会显著改善荧光粉的热猝灭性能。Gd的掺杂使荧光粉的发射波长红移,同时也会导致热猝灭性能的劣化。

白光LED用新型Ce,Pr掺杂的YAG单晶荧光材料的光谱性能研究

为了改善白光LED用荧光材料效率低、均匀性差、光衰大、寿命短及物化性能差等不足,本文采用单晶荧光材料取代荧光粉来制备白光LED,并对白光LED用新型YAG单晶荧光材料的制备和光谱性能进行了研究.采用提拉法生长了白光LED用Ce∶YAG及Pr,Ce∶YAG晶体,并通过吸收光谱,激发、发射光谱对晶体材料的光谱特性进行表征.研究表明,Ce∶YAG单晶荧光材料可以被发射波长460 nm左右的蓝光芯片有效激发,产生一个范围为480~650 nm宽峰发射.通过Pr3＋,Ce3＋离子共掺杂可以有效补偿Ce3＋离子单掺杂YAG荧光材料发光中的红色发光成分.

YAG∶Ce荧光粉的柠檬酸-凝胶法合成与表征

采用柠檬酸-凝胶法合成技术制备YAG∶Ce荧光粉,研究了Ce3+掺杂量、煅烧温度对荧光粉的光谱强度的影响。结果表明:当Ce3+掺杂量x≤0.07时,光谱强度随x增大而增强;当x>0.07时,光谱强度随x增大而减弱。随着煅烧温度的提高,粉体的结晶度不断提高,YAG∶Ce荧光粉的光谱相对强度逐渐增强。光谱的峰形和峰值不受温度和x的影响,主激发峰位于469nm,发射峰位于529nm。