發(fā)布時間：2019-02-25 18:55

【摘要】：近年來,隨著不可再生能源的不斷消耗,能源危機已經(jīng)成為舉世矚目的焦點。白光LED照明技術(shù)以其效率高、壽命長的特點逐漸成為照明顯示領(lǐng)域的主流,為緩解能源危機做出了重要的貢獻(xiàn)。因此,用于白光LED的熒光粉也越來越成為科研工作者研究的熱點,包括傳統(tǒng)的硅酸鹽、鋁酸鹽熒光粉。本論文主要研究了 KMg_4(P0_4)_3:Ce~(3+),Tb~(3+)和 Ca_~(2+)xLa_(8-x)(Si0_4)_60~(2-)x:Eu~(2+)兩種綠色熒光粉的晶體結(jié)構(gòu)和發(fā)光性能,并考察了其在白光LED領(lǐng)域的應(yīng)用價值。重點是非等價取代對熒光粉發(fā)光性能的影響。本論文分為四章:第一章為緒論,介紹了人類照明發(fā)展的歷史、白光LED技術(shù)、熒光粉的發(fā)光機理以及常用熒光粉。根據(jù)上述原理提出了本論文的實驗思路。第二章介紹了 KMg_4(P04)_3:Ce~(3+),Tb~(3+)熒光粉的制備和能量傳遞機理。同時,作為一個非等價取代的例子,本章深入地導(dǎo)論了 Ce~(3+)、Tb~(3+)在KMg_4(PO_4)_3晶格中的占據(jù)位。通過對KMg_4(PO_4)_3的晶體結(jié)構(gòu)進(jìn)行細(xì)致深入的分析,又結(jié)合XRD和EPR的測試結(jié)果,證明了 Ce~(3+)、Tb~(3+)均取代K~+的位置,同時為了平衡非等價取代時多余的正電荷,會有O~(2-)進(jìn)入到KMg_4(P04)_3晶格的管道中。實驗還發(fā)現(xiàn)Ce~(3+)可以很大程度上提高Tb~(3+)的發(fā)光強度。激發(fā)光譜、發(fā)射光譜以及熒光壽命曲線都證明了 Ce~(3+)和Tb~(3+)之間能量傳遞的存在。計算結(jié)果顯示在該熒光粉中能量傳遞的效率高達(dá)95%以上。通過理論分析,發(fā)現(xiàn)能量傳遞的機理是偶極-四極相互作用。第三章介紹了 Ca_~(2+)xLa_(8-x)(Si0_4)_6O_(2-0.5x):yEu~(2+)熒光粉的相關(guān)研究成果,包括合成方法、晶體結(jié)構(gòu)、發(fā)光性質(zhì)及其晶格中Eu~(3+)離子的還原機理。我們通過增加晶體中Ca_~(2+)離子的比例、減少La~(3+)離子的比例,成功使Eu~(3+)還原為Eu~(2+),從而大大增強熒光粉的綠光發(fā)射,峰值位于510nm。我們認(rèn)為由于Ca_~(2+)取代La~(3+)是不等價取代,使晶格中的O~(2-)離子數(shù)減少,從而降低Eu~(3+)被還原的難度。XANES測試結(jié)果表明隨著x值增大,熒光粉中Eu~(2+)離子的數(shù)目確實增多了。Rietveld精修結(jié)果顯示所得Ca_~(2+)xLa_(8-x)(Si0_4)_6O_(2-0.5x)(x=0、1、2)晶體均屬于六方晶系,空間群為P6/3m(176),且隨著x值增大,晶體中氧離子的量減少。EPR數(shù)據(jù)也證明了 Ca_~(2+)離子取代La~(3+)離子后,晶體中氧空位增多。這些結(jié)果都證明了我們提出的Eu~(3+)的還原機理。另外,我們還以Ca6La4(SiO_4)_6:0.04Eu~(2+)作為綠粉,配合365nm近紫外LED芯片和商用的藍(lán)粉、紅粉,成功地制得了顯色性良好的白光LED燈,這表明Ca_6La_4(SiO_4)_6:0.04Eu~(2+)綠色熒光粉具有商用于白光LED領(lǐng)域的應(yīng)用潛力。第四章對論文做出了總結(jié),指出了研究工作中不足的地方,為進(jìn)一步的研究提出了一些可行的意見。
[Abstract]:In recent years, with the constant consumption of non-renewable energy, energy crisis has become the focus of worldwide attention. White LED lighting technology has become the mainstream of lighting display field because of its high efficiency and long life. It has made an important contribution to alleviate the energy crisis. Therefore, the phosphor used in white LED is becoming more and more popular, including traditional silicate and aluminate phosphor. In this thesis, the crystal structure and luminescence properties of two kinds of green phosphors (KMg_4 (P0 / 4) _ 3, Tb~ (3) and Ca_~ (2) xLa_ (8) (Si0_4) _ (602 -) ~ (2 -) ~ (2 -) EU ~ (2) have been studied. The value of its application in the field of white light LED was also investigated. The effect of non-equivalent substitution on the luminescent properties of phosphors was studied. This paper is divided into four chapters: the first chapter is the introduction, introduces the history of human lighting development, white LED technology, phosphor luminescence mechanism and common phosphors. According to the above-mentioned principles, the experimental ideas of this paper are put forward. In chapter 2, the preparation and energy transfer mechanism of KMg_4 (P04) _ 3 and Tb~ (3) phosphors are introduced. At the same time, as an example of non-equivalent substitution, this chapter gives an in-depth introduction to the occupation of Ce~ (3) and Tb~ (3) in KMg_4 (PO_4) _ 3 lattices. By analyzing the crystal structure of KMg_4 (PO_4) _ 3 in detail and combining with the test results of XRD and EPR, it is proved that Ce~ (3) and Tb~ (3) replace the position of K ~, and that Ce~ (3) and Tb~ (3) take the place of K ~. At the same time, in order to balance the excess positive charge when the substitution is not equivalent, O2-will enter into the pipe of KMg_4 (P04) 3 lattice. It is also found that Ce~ (3) can greatly improve the luminescence intensity of Tb~ (3). Excitation spectra, emission spectra and fluorescence lifetime curves all prove the existence of energy transfer between Ce~ (3) and Tb~ (3). The calculated results show that the efficiency of energy transfer in the phosphor is over 95%. Through theoretical analysis, it is found that the mechanism of energy transfer is dipole-quadrupole interaction. In chapter 3, the related research results of Ca_~ (2) xLa_ (8 x) (Si0_4) _ 6O _ (2): yEu~ (2) phosphor are introduced, including the synthesis method, crystal structure, and so on. Luminescence properties and reduction mechanism of Eu~ (3) ion in lattice. By increasing the ratio of Ca_~ (2) ions in crystals and decreasing the proportion of La~ (3) ions, we have successfully reduced Eu~ (3) to Eu~ (2), thus greatly enhancing the green emission of phosphors with a peak value of 510 nm. We think that the substitution of Ca_~ (2) for La~ (3) is not equivalent, which reduces the number of O2-ions in the lattice, thus reducing the difficulty of reducing Eu~ (3). The XANES test results show that with the increase of x value, the number of O2-ions in the lattice decreases. The number of Eu~ (2) ions in phosphor did increase. Rietveld refined results showed that Ca_~ (2) xLa_ (8) (Si0_4) _ 6O _ (2) (x, 0. 5x) (x 0, 1, 2) crystals all belong to hexagonal system. The amount of oxygen ions in the crystals decreases with the increase of x value. It is also proved by EPR data that the oxygen vacancies in the crystals increase with the substitution of Ca_~ (2) ions for La~ (3) ions. All these results prove the reduction mechanism of Eu~ (3) proposed by us. In addition, we also used Ca6La4 (SiO_4) 6? 0.04 EU2 as green powder, combined with 365nm near ultraviolet LED chip and commercial blue powder and red powder, and successfully prepared white LED lamp with good chromaticity. The results show that Ca_6La_4 (SiO_4) 6? 0.04 EU2 green phosphor has the potential of commercial application in the field of white LED. The fourth chapter summarizes the paper, points out the deficiencies in the research work, and puts forward some feasible suggestions for further research.
【學(xué)位授予單位】：中國科學(xué)技術(shù)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TQ422

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

1 陳觀通;莊衛(wèi)東;胡運生;劉元紅;劉榮輝;何華強;;Luminescence properties of Eu~(2+) -doped Ba_3Si_6O_12N_2 green phosphor: concentration quenching and thermal stability[J];Journal of Rare Earths;2013年02期

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本文編號：2430440