稀土离子掺杂的纳米LuAG粉体的制备及其发光性能研究

发布时间：2018-03-23 09:59

  本文选题：LuAG:Ce　切入点：荧光粉　出处：《山东大学》2017年硕士论文

【摘要】：能源和环境一直是制约社会发展的重要因素,半导体白光LED因其节能、环保、高效、响应快、寿命长等优势,被称为二十一世纪的绿色照明新光源,越来越受到人们的广泛关注。Ce掺杂的LuAG(Lu3Al5O12)黄色荧光粉具有较高的量子效率和良好的热稳定性等优点,是一种潜在的可用于蓝光芯片激发型白光LED的高效荧光粉,但是目前Ce掺杂的LuAG荧光粉面临着制备工艺复杂、颗粒分散性差、发光效率低、红光成分缺失等缺点。本论文采用微波燃烧技术合成了 Ce掺杂的LuAG纳米荧光粉,系统研究了制备技术对LuAG:Ce荧光粉的微观结构和光学性能的影响;研究了 Sm,Pr,Eu,Cr分别掺杂的LuAG荧光粉的光谱性能;系统研究了 Sm,Pr,Eu,Cr分别与Ce共掺杂LuAG黄色荧光粉的光学性能。具体研究内容如下:以 Lu_2O_3、HNO_3、Al(NO_3)3·9H2O、Ce(NO_3)3·6H2O、甘氨酸等为主要原料,采用微波辅助溶液燃烧法制备了 Ce掺杂的LuAG黄色荧光粉。研究结果表明:950℃煅烧后,粉体呈现单一立方相结构,晶粒大小在20～30 nm范围内,粒度分布均匀。荧光粉的激发光谱包含348 nm和445nm处的两个激发带,说明荧光粉可以被蓝光有效激发;发射光谱是从460 nm跨越到650 nm的不对称宽发射带,发射峰在505 nm附近。当金属离子与甘氨酸的比例为1:0.5时,粉体表面杂质和缺陷少,发光强度最高。当Ce~(3+)的掺杂浓度在0～3.0mol%范围内时,随着Ce~(3+)掺杂浓度的不断增大,发光强度先增大后减小,同时发射峰发生红移。Ce~(3+)离子的猝灭浓度为1.0mol%,其浓度猝灭机理是电偶极与电偶极之间的相互作用。掺杂3wt%LiF后,荧光粉的结晶温度降低至850℃,发光强度提高了约3.5倍。添加10 mol%(N4)2SO4缓解了粉体的团聚现象,改善了粉体的发光性能,但(NH4)2SO4的分解消耗了部分热量,反而提高了 LuAG相的结晶温度。采用微波辅助溶液燃烧法制备了不同浓度Sm~(3+),Pr~(3+),Eu~(3+),Cr~(3+)分别掺杂的LuAG荧光粉,研究了荧光粉的光谱性能。LuAG:Sm荧光粉在406nm,418nm和466nm等处有较强激发峰,最强发射峰出现在618nm处,Sm~(3+)的猝灭浓度为1.50 mol%;LuAG:Pr荧光粉在451nm,460nm和474nm等处有较强激发峰,发射峰位于487nm,564nm和610nm处,其中在610nm发射处Pr~(3+)的猝灭浓度为0.50 mol%;LuAG:Eu荧光粉在382nm,394nm和466nm等处出现较强激发峰,发射峰位于 592 nm,610nm和710nm等处,Eu~(3+)的粹灭浓度10.00mol%;LuAG:Cr荧光粉的激发峰位于458 nm和575 nm处,发射峰位于565 nm,677 nm和704 nm处,当Cr~(3+)掺杂时,没有出现明显的浓度猝灭现象。研究结果表明,Sm~(3+),Pr~(3+),Eu~(3+),Cr~(3+)四种离子分别掺杂的LuAG荧光粉在蓝光区域内均出现了较强激发峰,且在橙光和红光区域出现了较强的发射峰,说明荧光粉均可以与InGaN蓝光芯片相匹配,并能发射橙光和红光。通过微波辅助溶液燃烧法制备了不同浓度Sm~(3+),Pr~(3+),Eu~(3+),Cr~(3+)分别与Ce~(3+)共掺杂的LuAG荧光粉,其中,在Sm~(3+),Pr~(3+)和Cr~(3+)分别与Ce~(3+)共掺杂的LuAG荧光粉的发射光谱中,除了有Ce~(3+)离子的黄色特征发射峰外,在618nm,610nm和704 nm等处分别出现了Sm~(3+),Pr~(3+)和Cr~(3+)离子的特征发射峰。Ce~(3+)和Sm~(3+),Pr~(3+),Cr~(3+)之间存在以非辐射跃迁方式为主的能量传递,能量从Ce~(3+)的5d激发态分别传递给Sm~(3+)的4G5/2能级、Pr~(3+)的3P0能级和Cr~(3+)的4T2g能级。Sm~(3+),Pr~(3+)和Cr~(3+)离子的共掺杂增强了荧光粉的橙光和红光发射,降低了荧光粉的色温,当Sm~(3+),Pr~(3+)和Cr~(3+)离子的掺杂浓度分别为3.0 mol%,1.0 mol%和1.0 mol%时,荧光粉的色温降低幅度最大,分别从7221.94K降低至6772.77K,6837.40K和6785.31K。Eu~(3+)离子的掺杂虽然也增加了红光发射,但是使Ce~(3+)离子出现了严重的发光猝灭。本文采用微波辅助溶液燃烧法,简单高效地合成了颗粒分布均匀的稀土离子掺杂LuAG纳米荧光粉。通过改善制备工艺,增强了荧光粉的发光强度,同时通过离子共掺杂弥补了红光成分的缺失,降低了荧光粉的色温,所制备的荧光粉在发展高效高显色白光LED照明光源等方面有着潜在的应用前景。
[Abstract]:Energy and environment is an important factor that restricts the development of society, semiconductor white light LED because of its energy saving, environmental protection, high efficiency, fast response, long life and other advantages, known as the green lighting a new light source in twenty-first Century, more and more people pay close attention to.Ce doped LuAG (Lu3Al5O12) yellow phosphor with high quantum efficiency and good thermal stability and other advantages, is a potential for blue chip excited white LED efficient fluorescent powder, but the current LuAG phosphors doped Ce facing complex preparation technology, particle dispersion, low luminous efficiency, lack of defects such as red component. This paper adopted microwave combustion LuAG nano phosphor Ce doped synthesis technology, studied the preparation technology of LuAG:Ce phosphor microstructures and optical properties; research of Sm, Pr, Eu, spectral properties of LuAG phosphor Cr doped; The system of Sm, Pr, Eu, Cr and Ce respectively. The optical properties of Co doped LuAG phosphors. The specific contents are as follows: Lu_2O_3, HNO_3, Al (NO_3) 3 - 9H2O, Ce (NO_3) 3 - 6H2O, glycine as the main raw materials, LuAG yellow phosphors doped with Ce were prepared by microwave assisted solution combustion method. The results showed that: 950 the calcined powder after a single cubic phase structure, grain size in the range of 20~30 nm, uniform particle size distribution. The excitation spectra of phosphors containing two nm and 348 445nm excitation band that phosphor can be effectively excited blue light emission; the spectrum is from 460 nm to 650 nm asymmetry across the broad emission band, the emission peak near 505 nm. When the metal ion and the proportion of glycine was 1:0.5, the surface of powder impurities and defects, the highest luminescence intensity. When Ce~ (3+) doping concentration in the range of 0 ~ 3.0mol%, with Ce~ (3+) doping Increasing the concentration of luminous intensity increases first and then decreases, while the red shift of emission peak of.Ce~ (3+) ion concentration quenching was 1.0mol%, the concentration quenching mechanism is the interaction between dipole and dipole. After doping 3wt%LiF, the crystallization temperature of the phosphor is reduced to 850 DEG C, the luminescence intensity is increased by about 3.5 times 10. Add mol% (N4) 2SO4 to ease the agglomeration of powder and improve the luminescent properties of the powder, but the decomposition of 2SO4 (NH4) part of the heat consumption, but increased the crystallization temperature of LuAG phase. Different concentrations of Sm~ were prepared by microwave assisted solution combustion (3+), Pr~ (3+) Eu~, (3+), Cr~ (3+) LuAG phosphors were doped, studied the spectral properties of.LuAG:Sm phosphor fluorescent powder in 406nm, 418nm and 466nm have strong excitation peaks, the strongest emission peak appeared at 618nm, Sm~ (3+) of the quenching concentration for 1.50 mol%; in LuAG:Pr phosphor 451nm, 460nm 鍜，

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