硼酸盐基白光LED用荧光粉的制备与发光性研究

发布时间：2018-01-22 14:51

  本文关键词： 硼酸盐 荧光粉 白光LED 发光性能 稀土掺杂　出处：《陕西科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：白光LED作为新一代照明和显示光源,具备绿色环保、效率高、使用时间长的优点。使用近紫外芯片与三基色荧光粉配合获得白光是生产白光LED的主流方法之一。随着研究和应用的扩展,人们对白光LED的发光性要求越来越高,然而如今该领域存在缺少高效红色荧光粉导致白光LED普遍显色差,色温高,以及能够与近紫外芯片良好匹配的红色绿色荧光粉种类较少的问题。因此,开发高效稳定的近紫外激发三基色荧光粉是LED领域的研究重点。硼酸盐具有合成温度低,结构稳定的特点,是性能优良的荧光粉基体。本文使用高温固相法对Na_3Gd_2(BO_3)_3和Y_2Ba_3B_4O_(12)两种硼酸盐系列的稀土荧光粉进行了合成,研究了不同掺杂离子及不同掺杂浓度荧光粉的晶体结构、微观形貌以及发光性能,并分析了荧光粉的发光机理。实验首先制备了不同煅烧温度和保温时长的Na_3Gd_(2-x)(BO_3)_3:xEu~(3+)荧光粉。各测试结果表明,当样品在800oC下煅烧,保温时间是5h时,其析晶情况最佳,发光最强。据此工艺参数合成了不同掺杂量的Na_3Gd_(2-x)(BO_3)_3:x Eu~(3+)荧光粉,样品均在350~400nm范围内有较强的激发峰,最强峰位于394nm处;发射光谱显示样品在592nm和614nm有两个主要发射峰,并以波长614nm的峰为主。当Eu~(3+)掺量为x=0.3,荧光粉的发射光最强,此时荧光粉的CIE色坐标为(0.650,0.350),与NTSC标准红光色坐标非常接近。利用多种离子共掺实现单一基质荧光粉的多色发射成为颇受关注的研究课题,在此背景下,利用Tb~(3+)和Eu~(3+)共掺,制备了能够被紫外和近紫外光有效激发的Na_3Gd_(2-x)-y(BO_3)_3:xTb~(3+),yEu~(3+)荧光粉。在368nm激发光下,其发射光谱中同时出现Tb~(3+)和Eu~(3+)的典型发射峰。当Eu~(3+)掺杂量渐渐增多,Tb~(3+)和Eu~(3+)之间通过电偶极-电偶极相互作用发生了能量传递,Tb~(3+)的特征发射逐渐减弱而Eu~(3+)的逐渐加强,荧光粉的色坐标出现绿色→黄色→橙色的渐变,实现了发光颜色的调节。此外,以Dy~(3+)掺杂制备Na_3Gd_(2-x)(BO_3)_3:xDy~(3+)单基质白光荧光粉。在353nm波长激发下,样品产生白光,主要发射光波长为479nm和574nm,且波长为574nm的黄光发射强度大于479nm的蓝光发射,荧光粉的色坐标也因此位于白光区域中偏黄光的位置。利用高温固相法进行制备,研究得到Y_2Ba_3B_4O_(12)基荧光粉最佳的工艺参数如下:预烧温度400oC,煅烧温度1150oC,保温时长3h。该工艺制度获得的样品经检测为纯相Y_2Ba_3B_4O_(12),析晶度高,微观下晶粒表面光滑,发光性能最好。利用该最佳工艺参数制备Y_(2-x)Ba_3B_4O_(12):xDy~(3+)荧光粉,样品在350~400nm波段内有明显激发峰,主要发射峰波长为480nm和575nm,在近紫外激发下呈白光发射。该荧光粉中Dy~(3+)的最佳掺杂量x=0.20,此时的色坐标为(0.386,0.412),与理想白光相比,Y_(2-x)Ba_3B_4O_(12):xDy~(3+)荧光粉发射光的色温有明显的降低。此外,实验利用Sm~(3+)掺杂制备了橙红色荧光粉Y_(2-x)Ba_3B_4O_(12):xSm~(3+)。该系列样品能够在紫外和近紫外光下被激发,主要激发峰的波长是403nm,主要发射峰分别位于562nm,602nm和647nm。Y_(2-x)Ba_3B_4O_(12):xSm~(3+)荧光粉的猝灭浓度为x=0.15,出现浓度猝灭的原因是能量在邻近的Sm~(3+)间以电偶极-电偶极作用方式的传递。荧光粉Y_(2-x)Ba_3B_4O_(12):xSm~(3+)的CIE坐标位于橙红色区,具有一定的开发应用潜能。
[Abstract]:As a new generation of white LED lighting and display light source, with green environmental protection, high efficiency, the advantages of long time use. Using near UV chip and phosphor for white light with three is one of the main production methods of white LED. With the expansion of research and application, people on the white LED light of increasingly high demand now, however, the existing lack of efficient red phosphor in general show white LED color, high color temperature, red green fluorescent powder and less species with near UV chip good matching problem. Therefore, the development of highly efficient and stable near ultraviolet excitation of three color phosphor is the focus of LED research field. With the synthesis of borate the characteristics of low temperature, stable structure, is the phosphor substrate with excellent properties. In this paper, using high temperature solid phase method of Na_3Gd_2 (BO_3) _3 and Y_2Ba_3B_4O_ (12) of two kinds of rare earth borate series of fluorescent powder The synthesis and crystal structure of different doped ions and different doping concentration of fluorescent powder, microstructure and luminescence properties of the phosphor luminescence mechanism and experimental analysis. Firstly, Na_3Gd_ different calcination temperature and holding time to prepare (2-x) (BO_3) _3:xEu~ (3+) phosphor. The test results show that when the samples at 800oC, calcination, holding time is 5h, the crystallization of the best, the most luminous. Different doped Na_3Gd_ was synthesized according to the process parameters (2-x) (BO_3) _3:x Eu~ (3+) phosphor samples have strong excitation peaks in the range of 350~400nm, the strongest peak is located at 394nm emission spectra of the sample; there are two main emission peaks at 592nm and 614nm, and the peak wavelength of 614nm. When Eu~ (3+) content was x=0.3, the strongest emission phosphors, the CIE chromaticity coordinates for (0.650,0.350), and NTSC standard red color coordinate is very close. 鍒╃敤澶氱�嶇�诲瓙鍏辨幒瀹炵幇鍗曚竴鍩鸿川鑽у厜绮夌殑澶氳壊鍙戝皠鎴愪负棰囧彈鍏虫敞鐨勭爺绌惰�鹃ⅲ�

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