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稀土铕掺杂红色荧光粉的制备与性能研究
张杰强
学位类型硕士
导师陈朝阳
2015-05-24
学位授予单位中国科学院大学
学位授予地点北京
学位专业材料物理与化学
关键词荧光 红色荧光粉 Sio2-pmm 复合薄膜 Mg2++ 耐水性 Alo2 
摘要

稀土掺杂碱土硫化物荧光粉具有较高显色指数以及良好的光学性能等特点而被广泛研究。但由于硫化物基体极易与空气中湿气以及二氧化碳反应而失去活性,严重制约了该类荧光粉的发展与应用。钙钛矿型荧光粉优良的光学性能以及良好的化学稳定性,使其成为潜在的白光LED 用红色荧光粉。改善其发光效率是发展该红色荧光粉的关键。本文采用溶胶凝胶法将SiO2 包覆在荧光粉CaS:Eu,Sm颗粒的表面,制备得到SiO2 包覆改性的荧光粉CaS:Eu,Sm;通过沉积法将PMMA 包覆在SiO2 改性的荧光粉CaS:Eu,Sm 颗粒的表面,进而得到SiO2-PMMA 复合包覆改性的荧光粉CaS:Eu,Sm。对制得的样品进行XRD、FT-IR、EDS 以及TEM 表征分析,结果表明:二氧化硅和PMMA 被成功地包覆在了荧光粉颗粒的表面,形成了有一层均匀致密的非晶态复合薄膜。荧光测试结果表明:经过非晶态复合薄膜包覆后,样品的荧光发射强度略有下降,但其荧光减弱的程度小于单独包覆二氧化硅的样品。原因是SiO2 和PMMA 的折射率分别为1.46 和1.49,它们之间具有良好的折射率匹配,所形成的非晶态复合薄膜减弱了荧光粉颗粒表面对光的散射。复合薄膜改性样品经过50 小时浸水老化后,其荧光发射强度仍可维持初始发射强度的85.9%。结果表明:非晶态复合薄膜极大地提升了荧光粉CaS:Eu,Sm的耐水性。本文分别通过在荧光粉CaTiO3 :Eu 的基体中引入Mg2+和2 AlO  离子而得到钙钛矿结构固溶体型红色荧光粉。XRD 表征结果表明:Mg2+和2 AlO  离子的引入没有改变荧光粉基质的晶格结构。当镁离子浓度为40mol%时,该荧光粉颗粒具有良好的形貌,粒径均匀分布于600-800nm 之间。Mg2+的引入降低了材料的晶格活化能,使得原料的熔融速率与形成固溶体的消耗速率相平衡,从而形成具有良好形貌的荧光粉颗粒。在398nm 光的激发下,荧光粉Mg0.4Ca0.6TiO3:Eu3+具有最优的荧光发射强度,是荧光粉CaTiO3 :Eu3+荧光发射强度的4.26 倍;当2 AlO  离子浓度为20mol%时,荧光粉Ca(TiO3)0.89(AlO2)0.22:Eu3+具有最优的荧光发射强度。在398nm光的激发下, 荧光粉Ca(TiO3)0.89(AlO2)0.22:Eu3+ 的荧光发射强度是荧光粉CaTiO3 :Eu3+的4.19 倍;在467nm 光的激发下,荧光粉Ca(TiO3)0.89(AlO2)0.22:Eu3+的荧光发射强度是荧光粉CaTiO3 :Eu3+的3.08 倍。综上所述,镁离子和2 AlO  离子的引入都能较为明显的增强该荧光粉的荧光发射强度,因此钙钛矿结构固溶体型红色荧光粉是一种极具光明前景的,可用于制作白光LED 的红色荧光粉。

其他摘要
The rare earth doped alkaline-earth sulfides (RE-doped AES) are widely researched because their high color rendering index and superior optical performance characteristics. However, the AES are very instability when they are exposed to moisture or other atmospheric components, which results that the applications of phosphors have been limited seriously. Perovskite-type phosphor has excellent chemical stability and optical properties, indicating that it is the potential red phosphor in making white-LED. It is the key to improve the luminous efficiency of the phosphor. In the article, SiO2 is covered onto the surface of the phosphor particles via sol-gel method and PMMA is encapsulated onto the surface of the phosphor particles by deposition. Results of XRD、FT-IR、EDS and TEM show that SiO2 and PMMA are covered onto the surface of the phosphor particles successfully, forming a uniform layer of dense amorphous composite film. The PL intensity of sample decreased slightly when it coated with SiO2-PMMA. But the degree of decline is less than the sample coated with SiO2. The reason for that there is a good refractive index match between PMMA (1.49) and SiO2 (1.46), which decline the dispersion of light. PL emission intensity of the phosphor coated with SiO2-PMMA is kept at about 85.9% when the sample is soaked into water for 50 h, implying that the amorphous composite film has an effective on protecting the optical properties of the phosphor. Results demonstrate that water-resistance of red phosphor CaS:Eu,Sm is enhanced by forming an amorphous composite film onto the surface of the phosphor particles. Types of perovskite solid solution red phosphors are obtained by introducing Mg2+ ions or ions into CaTiO3 host, respectively. Seen from the SEM images, it can be well known that spherical particles appeared and size of the phosphor particles are uniformly distributed in the range of 600-800 nm when the concentration of Mg2+ ions is about 40 mol%. Reason for that the activation energy of the lattice is reduced due to introducing Mg2+ into CaTiO3 host lattice, leading to balancing melting and consumption rate of raw materials. Thus, the uniform particles are formed when the concentration of the Mg2+ ions is the optimal concentration. The PL emission intensity (617 nm) of phosphor Mg0.4Ca0.6TiO3:Eu3+ is 4.26 times that of CaTiO3:Eu3+, when the concentration of Mg2+ ions is 40 mol%. The optimal concentration for obtaining the strongest PL emission intensity of Ca(TiO3)1-x/2(AlO2)x:Eu3+ is about 20 mol% of ions. The PL emission intensity (617 nm) of phosphor Ca(TiO3)0.89(AlO2)0.22:Eu3+ is 4.19 and 3.08 times that of phosphor CaTiO3:Eu3+, monitoring at 398nm and 467nm, respectively. As a consequence, the PL emission intensity of phosphors can be enhanced by introducing and Mg2+ ions, showing that perovskite solid solution type red phosphor is one of the most promising red-emitting phosphors in making tricolor phosphor converted White-LEDs.
文献类型学位论文
条目标识符http://ir.xjipc.cas.cn/handle/365002/4257
专题材料物理与化学研究室
作者单位中国科学院新疆理化技术研究所
推荐引用方式
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张杰强. 稀土铕掺杂红色荧光粉的制备与性能研究[D]. 北京. 中国科学院大学,2015.
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