高效蓝光芯片(LED)的问世，使得白光LED成为获得白光的重要方式，并发展为第四代照明光源。稀土荧光粉作为白光LED的中重要的光转换材料，成为研究领域的热点。随着蓝光LED的发射波段进一步向近紫外区域拓展，相匹配的荧光粉也要不断进行研发。大部分的三价稀土离子(Re³⁺)的发光源自4f-4f的组内跃迁，由于4f外层电子的屏蔽作用，其激发和发射峰位受基质影响相对较小，光谱特性相对固定。所以，本论文定位于f-d组间跃迁的过渡金属离子Cr³⁺和稀土离子Ce³⁺，研究其所处晶体场影响而体现出的光学特性的变化，也通过对其晶体场环境的强弱判断来推断其所处的具体格位。相互印证，不仅能完善理论对实践的指导，还能更好地探索新的基质材料来拓展荧光粉的类型。另外，也对目前高功率白光LED照明领域所缺失的绿光荧光陶瓷，进行了制备工艺的探索。本论文主要从以下四个方面进行展开： (1)在过去的近几年里，近紫外激发的三基色荧光粉成为获得白光LED的研究热点。发射位于400nm附近的芯片，是目前已有的效率最高的近紫外芯片(near-UV LED)。但是，目前大部分的蓝光荧光粉在400nm的激发并不十分有效。我们开发了新型蓝色荧光粉SrLu₂O₄:Ce³⁺，能够很好地与400nm近紫外LED匹配，且热稳定性优秀。在405nm激发下，发射出峰值为于460nm的，半高宽为90nm的宽带蓝光发射。优化得到的最佳离子掺杂浓度的样品，其内量子效率为76％。在150℃工作温度下，其发射强度仍然能保持室温下发射强度的86％。通过与商业黄光荧光粉和红光荧光粉混合，涂覆在405nm近紫外芯片上获得白光LED器件。通过调节组分的比重，能够在保持高显色指数(Ra≥90)的情况下，色温控制在3094-8990K范围内可调。以上这些特性都表明， SrLu₂O₄:Ce³⁺是有前景的近紫外激发的白光LED光转换用发光材料。 (2)先前关于在Ce³⁺掺杂的SrLn₂O₄类型荧光粉(Ln=Y,Lu,Sc等)中，只表现出一个发光中心，且为蓝光发射。在本章中，我们观察到了在SrLu₂O₄:Ce³⁺中的Ce³⁺的第二个发光中心。该发光中心可以在485nm激发下，发射出峰值位于600nm的宽带红光发射。我们认为，这个新的发光中心(Ce(II))是占据了Lu³⁺格位，而蓝光发光中心(Ce(I))是源自Sr²⁺格位的占据。光谱学分析表明，在低掺杂浓度下，优先形成Ce(I)发光中心，且发光中心的数量比Ce(I)／Ce(II)随着Ce³⁺掺杂浓度增加而明显减小，直到x达到0.004。两个发光中心的荧光寿命随着掺杂浓度的变化也进行了测量，可以观察到Ce(I)向Ce(II)的能量传递。当温度升高从83K到350K时，Ce(II)的发光强度的减弱的速度要明显快于Ce(I)中心，说明可以利用其相对发光强度比率来反映温度的变化，且在283K时，计算得相对敏感度高达2.28％K⁻¹。 (3)Cr³⁺掺杂的石榴石结构的Ca₂LuZr₂Al₃O₁₂(CLZA)荧光粉，是有前景的宽带近红外荧光粉，其激发峰能够与460nm蓝光芯片完美匹配。使用该荧光粉同460nm蓝光LED封装，获得750-850nm范围的近红外光的输出。而且，其电光效率为4.1％，要优于目前常规的钨灯的效率(2.9％)。在CLZA基质结构中，Cr³⁺占据Ca²⁺／Lu³⁺和Zr⁴⁺格位，分别形成两个发光中心Cr1、Cr2。对于CLZA:xCe³⁺,yCr³⁺系列样品，Ce³⁺和Cr³⁺分别占据正十二面体格位和正八面体格位，并对两种激活离子所处格位的晶体场强进行计算。由于Cr³⁺的吸收能力较弱这一固有属性，通过引入Ce³⁺作为敏化剂来提高荧光粉对近紫外光的吸收，并计算出Ce³⁺向Cr³⁺的高效的能量传递速率。在对CLZA:Cr³⁺样品的温度依赖性关系进行分析时，发现其升温过程有两个热过程，为低温热猝灭和高温热离化过程，并对两个过程的具体激活能进行了计算与分析。 (4)高功率白光LED／激光照明是照明领域的发展趋势，而荧光透明陶瓷又是高功率照明领域的重要光转换材料。针对目前荧光透明陶瓷的研究还是以黄光透明陶瓷为主，部分为红光氮化物陶瓷，而绿光透明陶瓷一直是研究的短板。所以，在前期关于黄光透明陶瓷(YAG:Ce³⁺)制备工艺的基础上，我们对Ca₃Sc₂Si₃O₁₂:Ce³⁺基绿光透明陶瓷的制备工艺进行了研究。首先对于结构更为复杂的Ca₃Sc₃Si₃O₁₂样品，采用先合成粉体再高温生长晶体的路径。先后从球磨介质、球磨时间和球磨转速等方面对粉体粒径分布的影响进行展开。得到了目前烧结条件下的“最优粒径分布”，以及直线透过率14％的绿光陶瓷样品。 关键词：稀土，荧光粉，镥酸锶，石榴石，透明陶瓷

 The advent of high-efficiency blue-light chips (LEDs) has made white LEDs an important way to obtain white light and developed into the fourth-generation lighting source. As a important optical conversion material in white LEDs, rare earth phosphors have become a hot topic in the research field. As the emission band of blue LEDs further expands to the near-ultraviolet region, matching phosphors are also being continuously developed. Most of the trivalent rare earth ions (Re³⁺) emit light from the intragroup transition of 4f-4f energy levels. Due to the shielding effect of the outer electrons of 4f orbits, the excitation and emission peaks are relatively less affected by the matrix, and the spectral characteristics are relatively fixed. Therefore, we locate the transition metal ion Cr³⁺ and rare earth ion Ce³⁺ in the transition between f-d groups, and study the change of optical properties reflected by the influence of the crystal field. It is also inferred the specific location by judging the strength of its crystal field environment. Mutual verification can not only improve the theoretical guidance of practice, but also explore new matrix materials to expand the type of phosphor. In addition, the preparation process of the green fluorescent ceramics missing in the field of high-power white LED is also explored. This paper is mainly carried out from the following four aspects: (1)We have developed a new blue phosphor SrLu₂O₄: Ce³⁺, which is well matched to 400nm near-ultraviolet LEDs and has excellent thermal stability. At 405 nm excitation, broadband blue light emission with a peak at 460 nm and a full width at half maximum of 90 nm is emitted. The optimized ion doping concentration of the sample obtained was optimized to have an internal quantum efficiency of 76%. At 150℃, its emission intensity can still maintain 86% of the emission intensity at room temperature. White LED devices were obtained by coating on a 405 nm near-ultraviolet chips by mixing with a commercial yellow phosphor and a red phosphor. By adjusting the specific gravity of the components, the color temperature control can be adjusted within the range of 3094-8990K while maintaining a high color rendering index (Ra ≥90). All of these characteristics indicate that SrLu₂O₄:Ce³⁺ is a promising near-ultraviolet-excited white LED light-converting luminescent material. (2)Previously, in the Ce³⁺ ion-activated SrLn₂O₄ type phosphor (Ln = Y, Lu, Sc, etc.), only one luminescence center was exhibited, and it was blue light emission. In this chapter, we observed the second luminescence center of Ce³⁺ in SrLu₂O₄: Ce³⁺. The illuminating center can emit a broadband red light emission with a peak at 600 nm under excitation of 485 nm. We believe that this new luminescent center (Ce(II)) occupies the Lu³⁺ position, while the blue illuminating center (Ce(I)) is derived from the Sr²⁺ position. Spectroscopic analysis shows that at low doping concentration, the Ce(I) luminescence center is preferentially formed, and the number of luminescence centers is significantly reduced compared with Ce(I)/Ce(II) as the Ce³⁺ ion doping concentration increases. x reached 0.004. The fluorescence lifetime of the two luminescent centers was also measured as the doping concentration was changed, and the energy transfer from Ce(I) to Ce(II) was observed. When the temperature rises from 83K to 350K, the luminescence intensity of Ce(II) decreases at a faster rate than the Ce(I) center, indicating that the relative luminescence intensity ratio can be used to reflect the temperature change, and at 283K, The relative sensitivity is calculated to be as high as 2.28 % K⁻¹. (3)The Ca₂LuZr₂Al₃O₁₂ (CLZA) phosphor with Cr³⁺ ion doped garnet structure is a promising broadband near-infrared phosphor with an excitation peak that perfectly matches the 460nm blue chip. Using this phosphor with a 460 nm blue LED package, an output of near-infrared light in the 750-850 nm range is obtained. Moreover, its electro-optic efficiency is 4.1%, which is better than the current conventional tungsten lamp efficiency (2.9%). In the CLZA matrix structure, Cr³⁺ occupies the Ca²⁺/Lu³⁺ and Zr⁴⁺ sites, forming two luminescent centers Crl and Cr2, respectively. For the CLZA:xCe³⁺, yCr³⁺ series of samples, Ce³⁺ and Cr³⁺ occupy the regular dodecahedral and regular octahedral positions, respectively, and calculate the crystal field strength of the two activated ions. Due to the inherent property of the weak absorption capacity of Cr³⁺, the absorption of near-ultraviolet light by the phosphor is increased by introducing Ce³⁺ ions as a sensitizer, and the efficient energy transfer rate of Ce³⁺ to Cr³⁺ is calculated. When analyzing the temperature dependence of CLZA:Cr³⁺ samples, it is found that there are two thermal processes in the heating process, which are low temperature thermal quenching and high temperature thermal ionization process, and the specific activation energy of the two processes is calculated and analysis. (4)High-power white LED/laser illumination is the development trend in the field of illumination, and fluorescent transparent ceramic is an important light conversion material in the field of high-power illumination. In view of the current research on fluorescent transparent ceramics, yellow light transparent ceramics are mainly used, and green light transparent ceramics has been a short board for research. Therefore, based on the previous preparation process of yellow transparent ceramic (YAG:Ce³⁺), we studied the preparation process of Ca₃Sc₂Si₂O₁₂:Ce³⁺-based green light transparent ceramics. First, for the more complex Ca₃Sc₂Si₂O₁₂ sample, the path of first synthesizing the powder and then growing the crystal at a high temperature is adopted. The effects of the particle size distribution on the particle milling medium, ball milling time and ball milling speed were developed. The "optimum particle size distribution" under the current sintering conditions and the green ceramic sample with a linear transmittance of 14% were obtained. Key Words: Rare earth, Phosphor, Strontium lutetite, Garnet, Transparent ceramics