稀土离子掺杂msi2o2n2mcasrba荧光粉的制备和荧光性能.pdf

南京航空航天大学 博士学位论文 稀土离子掺杂MSi2O2N2(M=Ca,Sr,Ba)荧光粉的制备和荧光性能 姓名：宋秀峰 申请学位级别：博士 专业：材料加工工程 指导教师：傅仁利 2010-10 南京航空航天大学博士学位论文 I 摘 要 白光 LED 由于具有高效、节能、环保、绿色照明、长寿命等优点而受到人们广泛的关注， 被预言将取代传统的照明光源－白炽灯、荧光灯等，成为第四代照明光源目前技术上最成熟 的白光 LED 的制备技术是荧光粉涂覆的光转换法其中荧光粉对白光 LED 性能起着至关重要 的作用因此探求新型的可被紫外光或蓝光芯片激发的白光 LED 用荧光粉成为目前白光 LED 研究工作的热点 硅基氮氧化物由 SiX4 (X = O,N) 四面体形成的网络组成，具有很高的化学和热稳定性富 氮的晶体场环境引起较大的电子云重排效应(nephelauxetic effect)和能级劈裂使发光中心（Eu2+、 Ce3+等）的 5d 能级重心降低稀土离子掺杂的硅基氮氧化物荧光粉的激发带覆盖紫外光和蓝光 区，正好与近紫外和蓝光 LED 芯片的发射光匹配氮氧化物荧光粉可调制出蓝、绿、黄和红等 各种不同波长的发射光谱，可满足白光 LED 的各种需求。

硅基氮氧化物荧光粉因具有优良的荧 光性能，被视为新型的制备白光 LED 理想的发光材料，吸引越来越多的人的关注本文以氮氧 化物 MSi2O2N2(M=Ca,Sr,Ba)为基质，研究稀土离子掺杂 MSi2O2N2(M=Ca,Sr,Ba)荧光粉的制备方 法，光谱特性和光谱调控等内容，主要的研究工作如下几个方面： 1. 采用传统的固相反应法和以硅酸盐为先驱体的两步法制备 MSi2O2N2:Eu2+(M=Ca,Sr,Ba)荧光 粉，研究制备工艺参数对 MSi2O2N2的物相组成和荧光性能的影响固相反应合成的产物含 有杂相且发光强度低采用以硅酸盐为先驱体的两步法制备的样品杂相含量低，发光强度 可提高 1.5 倍 2. 系统地研究 Eu2+或 Ce3+离子掺杂的 MSi2O2N2(M=Ca,Sr,Ba)荧光性能MSi2O2N2:Eu2+ (M=Ca,Sr,Ba)的激发光谱覆盖 250- 500nm 的紫外- 可见光区， 可与蓝光 LED 芯片匹配制备白 光 LED发射光谱峰值分别位于 560nm、535nm 和 490nm，是由 Eu2+的 4f65d? 4f7跃迁造 成的MSi2O2N2:Ce3+(M=Ca,Sr,Ba)激发光谱覆盖 250- 370nm 的紫外光区，发射光谱峰值分 别位于 390nm、395nm 和 396nm。

随着激活离子浓度的增加，发射光谱出现“红移”和浓 度猝灭现象 3. 研究共掺离子对 MSi2O2N2:Eu2+(M=Ca,Sr,Ba)的荧光性能的影响，共掺 Mn2+,Ce3+和 Dy3+可 提高 MSi2O2N2:Eu2+(M=Ca,Sr,Ba)的发光强度发现 Ce3+- Eu2+之间存在能量传递，计算了 Ce3+- Eu2+之间存在能量转换效率以及临界传输距离，发现 Ce3+- Eu2+之间的能量传递的主要 机制是电偶极- 电偶极之间的相互作用 4. 系统地研究了 CaSi2O2N2- SrSi2O2N2- BaSi2O2N2体系的互溶性以及 Eu2+离子在基质中的发射 光谱的可调性CaSi2O2N2与 SrSi2O2N2具有相同的晶体结构，可形成连续固溶体，Eu2+的 稀土离子掺杂 MSi2O2N2(M=Ca,Sr,Ba)荧光粉的制备和荧光性能 II 发射光谱连续可调； SrSi2O2N2与 BaSi2O2N2和 CaSi2O2N2与 BaSi2O2N2之间晶体结构各不相 同，只能在某些成分范围内形成固溶体，Eu2+的发射光谱只能在某些范围内进行调制。

关键词： MSi2O2N2(M=Ca,Sr,Ba)，氮氧化物，荧光粉，荧光性能，白光 LED 南京航空航天大学博士学位论文 III Abstract White light- emitting diodes (LEDs) have drawn much attention owing to their excellent properties, such as high luminous efficiency, low power consumption, environment friendly, reliability, long life and so on. White LEDs show high potential for replacement of conventional lighting like incandescent and fluorescent lamps, and are considered as the fourth generation solid- state lighting. Today, commercial white LEDs are phosphor- converted- LEDs, which connect a blue LED chip and the phosphor. The phosphor plays an important role in white LEDs for improving the color rendering index and luminescence efficiency. So it is necessary to develop new phosphors for white LEDs. Silicon- based (oxy)nitrides are generally built up of networks of crosslinking Si(O,N)4 tetrahedra. The excited state of the 5d electrons of rare- earth elements is significantly lowered to low energy due to large crystal- field splitting and a strong nephelauxetic effect as a result of a high degree of crosslinking Si(O,N)4 tetrahedra in the structure of silicon- based (oxy)nitrides. This enables silicon- based (oxy)nitride to be excited efficiently by UV or blue- light irradiation. The structural versatility of (oxy)nitride phosphors makes it possible to attain all the emission colors of blue, green, yellow, and red; thus, they are suitable for using in white LEDs. This novel class of phosphors has been seemingly the most promising materials nowadays because of their high thermal and chemical stability and excellent photoluminescence properties. In present work, a systematic research was carried out on the processing methods, luminescence properties, spectral tuning of the rare earth doped MSi2O2N2(M=Ca,Sr,Ba). The main work contents and achievements can be summarized as the following: 1, MSi2O2N2:Eu2+(M=Ca,Sr,Ba) phosphors were prepared through a conventional solid state reaction method and a two step method with M2SiO4 as a precursor. The effect of formation processing on phase type and luminescence properties of samples was investigated. Low firing temperature leads to the sample including impurities and low luminescence intensity. Due to forming low content of the intermediate phase, the sample by the two step method shows luminescence intensity 1.5 times higher than that by the conventional method. 2, Luminescence properties of Eu2+ or Ce3+ doped MSi2O2N2(M=Ca,Sr,Ba) were systematically investigated. The excitation bands of MSi2O2N2:Eu2+ (M=Ca,Sr,Ba) cover the spectral region from UV to the visible part(250- 500nm), the emission spectra show a single intense board emission band centered at 560nm,535nm and 490nm for M=Ca, Sr, Ba, respectively, which is ascribed to the allowed 4f65d? 4f7 transitions of Eu2+. The excitation spectra of MSi2O2N2:Ce3+(M=Ca,Sr,Ba) cover a broad 稀土离子掺杂 MSi2O2N2(M=Ca,Sr,Ba)荧光粉的制备和荧光性能 IV band from 250 to 370nm. The emission bands of MSi2O2N2:Ce3+ center at 390,395 and 396nm for M=Ca, Sr, Ba, respectively. With increasing the concentration of Eu2+or Ce3+, red- shift and concentration quenching of emission spectra were observed. 3, The effect of co- activator (Mn2+, Ce3+, and Dy3+) on the luminescence behavior of Eu2+ activated MSi2O2N2(M=Ca,Sr,Ba) phosphor was discussed in d。