發(fā)布時間：2018-10-09 18:36

【摘要】：白光LED是目前新興的綠色光源之一,具有節(jié)能、環(huán)保、壽命長、體積小、響應(yīng)速度快等優(yōu)勢,應(yīng)用前景廣闊。YAG熒光粉性能對白光LED的光色性能有著至關(guān)重要的影響。目前商用的YAG熒光粉使用傳統(tǒng)的高溫固相法制備,顆粒尺寸過大且粒徑分布范圍不均勻。制備高結(jié)晶性細(xì)粒徑Y(jié)AG熒光粉是本領(lǐng)域的研究難點,也具有良好的應(yīng)用前景。本文首先研制出微米級α-Al2O3分散粉體和納米Y2O3粉體,并以其為原料研究熔鹽法制備高結(jié)晶性分散YAG粉體的技術(shù),通過控制反應(yīng)過程,成功制備出小粒徑的YAG顆粒。本文采用化學(xué)沉淀法制備出微米級α-Al2O3粉體,研究了攪拌速度、促進劑、分散劑、熱處理工藝等參數(shù)對α-Al2O3顆粒粒徑及形貌的影響。研究表明：攪拌速度提高可以減小α-Al2O3顆粒的粒徑；加入促進劑NH4F能夠控制α-Al2O3趨于片狀生長；提高煅燒溫度有利于得到小粒徑的α-Al2O3顆粒；采用隨爐加熱的方式并適當(dāng)提高保溫時間可以得到形貌規(guī)則的顆粒。在此基礎(chǔ)上制備出粒徑在3μm左右、分散性良好的片狀α-Al2O3粉體。本文分別使用尿素沉淀法和碳酸氫銨沉淀法制備出納米Y2O3粉體,研究發(fā)現(xiàn)：尿素沉淀法制備的顆粒粒徑過大；碳酸氫銨沉淀法制備出小粒徑的Y2O3顆粒；煅燒溫度越低,越有利于顆粒的分散性。本文最終制備出100nm左右的Y2O3顆粒。本文以自制的α-Al2O3和納米Y2O3粉體為原料,采用熔鹽法制備出粒徑小于5μm的YAG粉體。研究了不同熔鹽體系、焙燒溫度等因素對YAG產(chǎn)物的影響,并對制備工藝進行了改進,研究了三次處理對制備YAG顆粒的影響。研究發(fā)現(xiàn),在NaCl熔鹽中,當(dāng)反應(yīng)溫度較低時,納米Y2O3顆粒包裹在α-Al2O3顆粒表面；將此包裹體在KCl熔鹽中1200℃焙燒,包裹更為致密；再在K2SO4熔鹽中1400℃焙燒處理,成功得到小粒徑的YAG顆粒,顆粒大小與α-Al2O3模板存在依賴性。本文分析了α-Al2O3模板法制備小粒徑Y(jié)AG顆粒的機理。本文認(rèn)為,熔鹽促進了納米Y2O3顆粒運動到α-Al2O3顆粒表面；在接觸點生成Y4Al2O9相；隨著溫度的升高,在α-Al2O3和Y2O3顆粒的界面進一步生成中間相YAlO3。最終轉(zhuǎn)化為YAG單相。
[Abstract]:White LED is one of the new green light sources. It has the advantages of energy saving, environmental protection, long life, small size and fast response. At present, commercial YAG phosphors are prepared by traditional high temperature solid state method. The particle size is too large and the particle size distribution is uneven. The preparation of YAG phosphors with high crystallinity and fine particle size is a difficult point in this field and has a good prospect of application. In this paper, micrometer 偽 -Al 2O 3 dispersion powder and nanometer Y2O3 powder were prepared, and the technology of preparing high crystalline dispersed YAG powder by molten salt method was studied. Small diameter YAG particles were successfully prepared by controlling the reaction process. In this paper, micrometer 偽 -Al _ 2O _ 3 powders were prepared by chemical precipitation method. The effects of stirring speed, accelerator, dispersant and heat treatment process on the size and morphology of 偽 -Al _ 2O _ 3 particles were studied. The results show that the particle size of 偽 -Al _ 2O _ 3 particles can be reduced with the increase of stirring speed, the growth of 偽 -Al _ 2O _ 3 particles can be controlled by adding accelerator NH4F, and the small size 偽 -Al _ 2O _ 3 particles can be obtained by increasing the calcination temperature. The particles with regular morphology can be obtained by heating with furnace and properly increasing the holding time. On this basis, the flake 偽 -Al _ 2O _ 3 powders with a particle size of about 3 渭 m and good dispersion were prepared. In this paper, nanometer Y2O3 powders were prepared by urea precipitation method and ammonium bicarbonate precipitation method respectively. It was found that the particle size of urea precipitation method was too large, the small diameter of Y2O3 particles was prepared by ammonium bicarbonate precipitation method, and the calcining temperature was lower. The better the dispersity of the particles is. In this paper, Y2O3 particles about 100nm were prepared. In this paper, 偽 -Al _ 2O _ 3 and nano-sized Y2O3 powders were used as raw materials to prepare YAG powders with diameter less than 5 渭 m by molten salt method. The effects of different molten salt system, calcination temperature and other factors on the YAG products were studied, and the preparation process was improved. The effect of three treatments on the preparation of YAG particles was studied. It is found that when the reaction temperature is low, the nanocrystalline Y2O3 particles are encapsulated on the surface of 偽 -Al _ 2O _ 3 particles in the NaCl molten salt, the inclusion is calcined at 1200 鈩，

本文編號：2260364