白光LED用YAG:Ce3+荧光粉制备技术的研究进展

简要论述了国内外对YAG:Ce3 荧光粉的研究现状,重点介绍了近年来用于高效蓝光LED激发形成白光的YAG:Ce3 荧光粉合成的新方法和新工艺,对高温固相反应法、溶胶-凝胶法、化学沉淀法、气相法等方法的优缺点进行了综合比较。最后,展望该领域的发展前景及今后的研究趋势。     

蓝光转换白光荧光粉YAG:Ce3+的研究进展

本文综述了YAG：Ce^3 发光粉合成的各种方法。对高温固相反应,溶胶—凝胶法,喷雾热解法和共沉淀法进行了比较,对该荧光粉的合成方法及今后的研究趋势进行了展望。     

YAG:Ce3+荧光粉的制备与发光性能

采用高温固相法制备Y3-xAl5O12:xCe3+(x=0.05～0.9)荧光粉,利用荧光光谱仪、X射线衍射仪和扫描电镜等对样品的发光性能、物相和形貌进行了测试分析.研究了Ce3+浓度、助熔剂、灼烧温度、灼烧时间等对样品发光性能的影响.结果表明,以Al(OH)3为原料,采用氟化物助熔剂可以获得颗粒细小均匀的荧光粉,研究结果对荧光粉的生产具有一定的意义.     

顺序共沉淀法制备Nd:YAG陶瓷

以NH4Al(SO4)2·12H2O、Y2O3、Nd2O3为原料,NH4 HCO3为沉淀剂,采用顺序共沉淀法制备Nd:YAG粉体.并研究了碳酸氢铵浓度对粉体性能的影响,研究结果表明:较佳的碳酸氢铵浓度为1.0 mol/L.制得的粉体颗粒尺寸小,粒度分布窄,分散性好,具有良好的烧结活性,在1800℃真空烧结15 h制备了Nd:YAG透明陶瓷,其近红外波段的透过率为78％.断面和表面形貌显示陶瓷晶粒尺寸均匀,晶界清晰,结晶性好,瓷体致密,平均晶粒尺寸约为15 μm.     

丙二酸溶胶-凝胶法合成亚微米级YAG:Ce,Gd黄色荧光粉

以丙二酸为络合剂,通过溶胶-凝胶法合成了亚微米级YAG:Ce,Gd黄色荧光粉.采用TG/DSC、XRD研究干凝胶热分解和YAG晶相形成的过程;通过荧光光谱分析了Gd~(3+)的掺杂对荧光粉的发光强度的影响规律;通过SEM观察粉体的微观形貌.结果表明:经1200 ℃煅烧3 h得到的荧光粉,粉体粒径为0.3～1 μm,颗粒规则接近球形;随着Gd~(3+)掺杂量的增加,荧光粉的发射光谱由525 nm红移到550 nm.     

不同燃烧剂对合成YAG:Ce3+黄色荧光粉的影响研究

本文采用燃烧法,分别选取尿素、甘氨酸和柠檬酸作为燃烧剂,成功合成了YAG:Ce3+黄色荧光粉.采用XRD和PL光谱分析,研究了不同燃烧剂对荧光粉结构及荧光性能的影响.结果表明,所有样品均为纯相的Y3Al5O12,以尿素作为燃烧剂时,合成的荧光粉的结晶性最好,荧光强度最强.YAG:Ce3+荧光粉可被450 nm的蓝光激发...     

化学共沉淀法制备Yb:YAG纳米粉体的研究

以碳酸氢铵或氨水为沉淀剂,采用化学共沉淀法制备Yb:YAG透明陶瓷纳米粉体,利用扫描电镜、X射线衍射对粉体的形貌和物相结构进行表征。研究表明:以碳酸氢铵为沉淀剂制备的前驱体在1 200℃煅烧后可制得无杂质的YAG(Y3Al5O12)粉体,以氨水为沉淀剂制备的前驱体在1 200℃煅烧后制得的YAG粉体中有杂质相YAM(Y4Al2O9);以碳酸氢铵为沉淀剂制备的YAG粉体的分散性好,碳酸氢铵溶液与母盐溶液中铝离子浓度最佳配比为10∶1,粉体粒度在100~250 nm。     

均相法和共沉淀法制备Nd：YAG透明陶瓷的对比研究

以Al(NO3)3·9H2O、Y2O3、Nd2O3、尿素和NH4HCO3为主要原料,分别采用均相法和共沉淀法制备了Nd:YAG纳米粉体和透明陶瓷。对比研究了两种方法的粉体的制备工艺,物相,形貌和陶瓷的透过率、形貌。结果发现,均相法制备的前驱体疏松,1200℃煅烧时先形成YAP相,后形成纯相粉体。共沉淀法制备的前驱体较硬,1000℃锻烧直接形成纯相粉体。最后,两种方法制备的陶瓷素坯经真空烧结、处理后,在1064 nm的透过率达80%。共沉淀法条件温和,易于得到纯相YAG,更适合于工业化开发。     

共沉淀法制备Al2O3:Eu红色荧光粉及其发光性能研究

用碳酸氢铵和氨水混合溶液作为复合沉淀剂制备了Al2O3：Eu红色荧光粉体。采用X射线衍射（XED）对粉体制备过程中的相变进行了研究。通过荧光分光光度计分析了Eu掺杂浓度和煅烧温度对Al2O3：Eu粉体发光性能的影响。研究结果表明：采用共沉淀法制备工艺，经过1050℃煅烧4h，可以得到发光强度高的荧光粉体。Eu^3＋离子的最佳掺杂浓度为1mol％，在波长为254nm紫外光激发下，最强的发射波长出现在614nm附近。     

煅烧气氛对均相沉淀法制备YAG∶Ce荧光粉性能的影响

按照化学计量比Y2.94Ce0.06 Al5O12,采用均相沉淀法制备了YAG∶ Ce荧光粉的前驱体,并将制得的前驱体分别在空气气氛,惰性气氛(N2)和还原性气氛(CO)下煅烧.采用热分析和X射线衍射图谱研究了产物在煅烧过程中相的演变过程以及最终产物相的组成.结果表明,当在空气中煅烧时,大量Ce3激活离子被氧化成Ce4并在基质中析出成为CeO2相;在CO气氛中煅烧的样品中存在中间相(YAM),证明在相同煅烧温度下该气氛不YAG晶相的形成.荧光光谱表明,YAG晶相的形成和Ce3离子的氧化对样品的发光性能有很大的影响.当在均相沉淀过程中添加聚乙二醇分散剂并在氮气气氛下煅烧后,产物的荧光性能得到大幅度提升.     

YAG：Ce荧光粉的撞击流共沉淀-熔盐煅烧法制备及性能

采用撞击流共沉淀法和直接共沉淀法制备掺铈钇铝石榴石（Y3Al5O12：Ce,YAG：Ce）前驱体,用熔盐法煅烧前驱体制备黄色YAG：Ce3＋荧光粉。用X射线衍射仪、热重-差热分析仪、扫描电镜、荧光分光光度计等测试设备研究前驱体制备方法和煅烧方法对粉体结构、形貌和发光性能等的影响。结果表明：以碳酸氢氨为沉淀剂,采用撞击流...     

Preparation and characterization of YAG:Ce thin phosphor films by pulsed laser deposition

We report the use of YAG:Ce phosphor as the raw material to make thin and transparent phosphor films with pulsed laser deposition including the effects of heating temperature, target–substrate distances, annealing times, and annealing atmosphere on the YAG:Ce³⁺ phosphor film crystal types and spectral properties. The results indicated that at a coating temperature of 350°C, the YAG:Ce³⁺ phosphor film had the best crystallinity with an intact film and maximum fluorescence emission. The crystallinity and fluorescence emission intensity of the film gradually decreased as a function of increasing target–substrate distances. As the annealing time increased, the crystallinity and the fluorescence emission intensity of the film first increased and then decreased. The film made with 5 h of annealing had the best crystallinity and the highest fluorescence emission intensity. The crystallinity of the film annealed under air was higher than that made under nitrogen; the fluorescence intensity of the film under air was slightly lower than the film under nitrogen. The emission peak of the prepared film was at 523 nm when excited at 450 nm. This is slightly blue‐shifted versus the emission of commercial phosphor powders. This study offers a theoretical basis for the development of transparent phosphor films.     

Fabrication of Ce:YAG,Ce,Cr:YAG and Ce:YAG/Ce,Cr:YAG dual-layered composite phosphor ceramics for the application of white LEDs

(Ce_0.001Y_0.999)₃Al₅O₁₂ and (Ce_0.001Y_0.999)₃(Cr_xAl_1−x)₅O₁₂ (x=0.001−0.005) transparent ceramics were synthesized by the solid state reaction and vacuum sintering and their optical properties were measured. High quality white light was obtained when the Ce:YAG/Ce,Cr:YAG dual-layered composite ceramic was directly combined with commercial blue LED chip. A maximum luminous efficacy exceeding 76 lm/W at a low correlated color temperature of 4905 K was obtained. The color temperature can be controlled by variations of Cr³⁺ concentration and the ceramic thickness. Hence, the Ce:YAG/Ce,Cr:YAG dual-layered composite phosphor ceramic may be a promising candidate for white LEDs.     

Porous Ce:YAG ceramics with controllable microstructure for high-brightness laser lighting

In order to meet the increasing demand for high-power laser diode lighting and displays, phosphor converters with high-brightness and high-directionality ought to be constructed to enhance the luminance and luminous efficacy. However, the pores formed during the sintering of phosphor ceramics affect the scattering effect and directionality of light. Therefore, porosity optimization and pore size regulation need to be explored. In this work, a series of Ce:YAG ceramics with various porosities and pore sizes were prepared. The influences of porosity and pore size on the microstructure, light confinement ability, and optical properties of Ce:YAG ceramics were studied. The ceramic phosphor with a porosity of 10 vol.% and a pore size of 3 μm exhibits a good spot confinement ability and shows a high luminous flux value of 3430 lm and a central luminance (1669 592 cd/m²) under blue laser excitation. The 10 vol.% Ce:YAG ceramic phosphor with a pore size of 5 μm has the highest emission intensity and gives a maximum luminous efficacy of 268 lm/W and a luminous flux of 4020 lm under 30 W/mm² blue laser excitation. Thus, the porous Ce:YAG ceramics are expected to be a promising candidate for high-brightness laser lighting and projection applications.     

Optical performances of mono‐dispersed spherical YAG:Ce3+ nano‐phosphor achieved by one‐pot synthesis

Mono‐dispersed spherical YAG:Ce³⁺ nano‐phosphors were successfully synthesized by a one‐pot glycol‐thermal process using aluminum isopropoxide, yttrium, and cerium acetate hydrates as the precursor, (1,4)‐butanediol as the solvent, ethidenediamine as the additive agent that can both control the morphology and improve the optical performances of the as‐achieved products. The as‐prepared YAG:Ce³⁺ nano‐phosphors displayed mono‐dispersed spheres of about 150 nm and an improved optical performance with a quantum yield (QY) of 41% and good photostability, indicating that they have a considerable potential to be applied in solid‐state lighting or used as coatings in other optical electronic devices.     

YAG：Ce3＋黄色荧光粉的高温固相法制备

采用高温固相法制备了Ce3＋激活的钇铝石榴石荧光粉Y3Al5O12：Ce3＋（YAG：Ce3＋）。采用X射线衍射法对所制备的样品进行结构分析,采用荧光光谱仪对样品进行发光分析。结果表明,在YAG：Ce3＋的高温固相法制备过程中原材料和助熔剂用量以及稀土离子掺杂量、研磨时间、灼烧温度和时间等,都会对所制备样品的成相和发光性能产生影响。     

Anomalous enhancement of photoluminescence intensity of sintered YAG:Ce particles‐embedded glasses

For high‐power white LED applications, YAG:Ce‐based yellow phosphors were embedded in a low‐T_g Bi₂O₃–B₂O₅–ZnO–Sb₂O₅ glass by sintering route. Effects of sintering temperature (325‐390°C) on the microstructure and photoluminescence properties were investigated. X‐ray diffraction was used to measure the retained fraction of YAG:Ce phase after sintering. Scanning electron microscope and transmission electron microscope, equipped with energy‐dispersive X‐ray spectrometry, were used to examine the microstructure, including the element distribution across the phosphor–glass interface. Photoluminescence properties of the samples before and after sintering were compared. With the increasing sintering temperature, the retained fraction of YAG:Ce decreased from 83.3% to 82%. This effect tends to reduce the luminescence intensity of the samples after sintering. The increasing sintering temperature also enhances the diffusion of cations (esp. Bi) from glass matrix to YAG:Ce. This effect tends to increase the luminescence intensity of the YAG:Ce particles after sintering. When the sintering temperature was lower (325°C), the effect of YAG:Ce loss was dominant, thus the luminescence intensity was reduced after sintering. When the sintering temperature was higher (350‐390°C), the effect of solute dissolution was dominant, resulting in luminescence intensity anomalously higher than that before sintering. Similar result has not been reported in literatures. The maximum luminescence intensity of the sintered samples is 1.57 times as high as that of the samples before sintering.     

溶剂热法合成YAG：Ce粉体及其表征

本文以Al（NO3）3·9H2O、Ce（NO3）3·6H2O和Y2O3为原料,碳酸氢铵为沉淀剂制备反应前驱体,乙二胺作为反应介质,采用溶剂热法在230℃下保温10h合成了YAG：Ce粉体。利用X射线衍射（XRD）、透射电子显微镜（TEM）和红外光谱分析（FT～IR）等测试手段,对所制备样品的结构和形貌进行了表征。