【作者】 王美媛；

【导师】 张家骅； 王笑军；

【作者基本信息】 中国科学院研究生院（长春光学精密机械与物理研究所） ， 凝聚态物理， 2010， 博士

【摘要】 目前,Eu²⁺激活的氮氧化物荧光粉是一系列备受关注的用于白光LED的下转换荧光材料,其不但具有优越的光致发光性质,而且具有优越的热和化学稳定性。该系列的荧光粉可以强烈的吸收从近紫外到可见光谱区域的光,因此这种荧光粉可以做为一种适合封装白光LED的荧光材料和近紫外或蓝光（460nm）的半导体芯片匹配。可被X-ray或者阴极射线激发的长余辉荧光粉是一种适合应用在雷达示波器上显示雷达回波的荧光材料,具有这种长余辉性质的荧光材料还很少。本论文采用高温固相反应法合成了一系列Eu²⁺掺杂的氮氧化物荧光粉,并研究了它们的结构、发光和长余辉性质,取得的主要研究成果如下:（1）调节Eu²⁺的浓度,可以发现Ca_1-xEu_xSi₂O_2-δΝ_2+2δ/3系列荧光粉的激发带边随着Eu²⁺浓度的增加逐渐向长波方向移动,并且在460nm左右的蓝光区域形成了一个强的激发带,随着Eu²⁺浓度的增加,该激发带越来越强。（2）合成了组分为Ba₂SiO₄:0.01Eu²⁺-xSi₃N₄ （x = 0.03, 0.1, 0.3, 0.5, 0.7, and 1.0）系列的长余辉荧光粉,并发现当x < 0.1的时候,粉末的结构为Ba₂SiO₄的立方相,当撤掉激发源后,产生505nm的蓝绿色余辉;当x = 0.1的时候,粉末的晶格结构为Ba₂SiO₄的立方相,撤掉激发源后产生490nm的BaSi₂O₂N₂:Eu²⁺相的蓝绿色余辉;随着x从0.1增加到1,粉末的晶格结构显示从Ba₂SiO₄的立方相向BaSi₂O₂N₂的单斜相转变,但撤掉激发源以后却全部产生了490nm的蓝绿色余辉。（3）合成了组分为2BaCO₃- ySi₃N₄:0.01Eu²⁺ （y = 1/6, 1/4, 1/3, and 1.0）系列的长余辉荧光粉,并发现该当y > 1/6,粉末的晶格结构为Ba₂SiO₄的立方相,且其余辉发射为505nm的蓝绿光;当y = 1/6的时候,XRD图中并没有清晰的衍射峰出现,而是形成了低温的共熔混合物。但是其余辉发射显示的确是590nm的桔黄色光,这应该是属于Ba₃SiO₅:Eu²⁺的晶相。经过比较得到2BaCO₃- ySi₃N₄:0.01Eu²⁺ （y = 1.0）的余辉发射强度大约是Ba₂SiO₄:0.01Eu²⁺-xSi₃N₄ （x = 0.03）的7倍。（4）为了进一步增强Ba₂SiO₄:Eu²⁺相长余辉的磷光强度,在实验2的基础上,向该反应原料中加入了适当的BaCO₃,得到组分是Ba₂SiO₄:0.01Eu²⁺-xSi₃N₄- 2BaCO₃系列Ba₂SiO₄:Eu²⁺相的长余辉荧光粉,且晶格结构不随Si₃N₄含量的变化而变化。当x = 1.0时,其余辉发射强度最强,大约是2BaCO₃- ySi₃N₄:0.01 （y = 1.0）的3倍。更多还原

【Abstract】 Eu²⁺-activated oxynitride phosphors are a series of down-conversion phosphors for white light-emitting diodes, which have drawn much attention to their wide applications in various fields. The oxynitride phosphors have excellent photoluminescence properties and outstanding thermal and chemical stability. They can match the UV and blue LED chip very well as the phosphors for white light-emitting diodes because of their strong absorption in the ultraviolet and visible light spectral region. The long-lasting phosphorescence phosphors for X-ray and cathode ray tubes can be applied in screen of radar. The main purpose of this work is to synthesize Eu²⁺-doped oxynitride phosphors and research their crystal structures, photoluminescence and long-lasting phosphorescence properties, the main results obtained are listed as follow:（1） Tuning Eu²⁺ concentration, it is observed that the photoluminescence excitation band edge of Ca_1-xEu_xSi₂O_2-δΝ_2+2δ/3 shifts to the longer wavelength side, following the formation of a strong excitation band at around 460 nm and this band becomes stronger with an increase in Eu²⁺ concentrations.（2） Synthesized the phosphors with the composition of Ba₂SiO₄:0.01Eu²⁺-xSi₃N₄ （x = 0.03, 0.1, 0.3, 0.5, 0.7, and 1.0）. The XRD patterns of the samples are consistent with the Ba₂SiO₄ orthorhombic phase when the Si₃N₄ content is equal to or less than 0.1. After the removal of X-ray excitation source, the phosphor shows a weak LLP peak at 505 nm; When x = 0.1, the crystal structures of phosphors are consistent with the Ba₂SiO₄ orthorhombic phase. After the removal of X-ray excitation source, the phosphor shows bluish-green LLP peak at 490 nm; With increasing x from 0.1 to 1, BaSi₂O₂N₂ monoclinic phase is gradually formed and finally dominates the crystal phase as x = 1, the PL spectra are in accordance with the PL spectrum of BaSi₂O₂N₂:Eu²⁺ only, peaking at 490 nm.（3） Synthesized the phosphors with the composition of 2BaCO₃- ySi₃N₄: 0.01Eu²⁺ （y = 1/6, 1/4, 1/3, and 1.0） The XRD patterns of the samples are consistent with the Ba₂SiO₄ orthorhombic phase for y > 1/6; when y = 1/6, the content of Si₃N₄ may be too small to form a crystal phase but forms a eutectic mixture, the LLP spectrum shows a single broad orange-red band with a maximum at 590 nm, which should belong to the Ba₃SiO₅:Eu²⁺ phase. LLP of 2BaCO₃-ySi₃N₄: 0.01Eu²⁺ （y = 1.0） is detected to be enhanced by a factor of 7 in comparison with that of Ba₂SiO₄:0.01Eu²⁺–xSi₃N₄ （x = 0.03）.（4） In order to improve the LLP intensity of the Ba₂SiO₄:Eu²⁺ phase, add some BaCO₃ into Ba₂SiO₄:0.01Eu²⁺-xSi₃N₄ and obtain the LLP phosphors with the composition of Ba₂SiO₄:0.01Eu²⁺-xSi₃N₄-2BaCO₃. The crystal structures of phosphors belong to Ba₂SiO₄ orthorhombic phase. When x =1.0, the LLP intensity is about three times as strong as that of 2BaCO₃- ySi₃N₄: 0.01Eu²⁺ （y = 1.0）.更多还原