【作者】 卢鹏志；

【导师】 何大伟；

【作者基本信息】 北京交通大学 ， 光学工程， 2008， 硕士

【摘要】 PDP用的荧光粉引起了越来越多学者的重视，晶体中掺杂稀土离子的相关研究已成为人们研究的热点。由于硅酸盐基质具有较高的化学稳定性和较好的结晶性，是一类性能优良基质材料。本文采用高温固相法研究制备了稀土离子掺杂的M₂SiO₄碱土金属系列硅酸盐荧光粉，并对其结构特性及发光性能进行了研究。M₂SiO₄：RE(M=Mg,Sr,Ba,RE=Tm³⁺,Tb³⁺)的X射线粉末衍射数据与JCPDS标准卡片（87-0061，39-1256，26-1403）符合得很好。稀土激活离子的掺入没有引起基质结构的明显变化，表明我们合成的材料是碱土金属正硅酸盐，属于M₂SiO₄型化合物，属于正交型晶系。监测457nm时，M₂SiO₄（M=Mg,Sr,Ba）：Tm³⁺的真空紫外激发谱中，存在两个位于170nm，190nm附近的激发峰和一个位于211nm-300nm附近的激发带。前者主要是硅酸盐基质的吸收，并且按照离子半径Mg²⁺＜Sr²⁺＜Ba²⁺的顺序，硅酸盐基质的吸收随着离子半径的增加向短波方向移动；后者是由于Tm³⁺与近邻的O^2-发生电荷迁移而产生的，随着离子半径的增加逐渐减弱。在161nm真空紫外激发下的主要发射峰分别位于357nm，459nm，478nm附近，分别对应于Tm³⁺的¹D₂→³H₆、¹D₂→³H₄、¹G₄→³H₆能级的跃迁，并且随着碱土离子的不同，相对应¹D₂→³H₆、¹D₂→³H₄、¹G₄→³H₆能级的跃迁发射峰的强度也发生变化。监测545nm时，Ba₂SiO₄：Tb³⁺的真空紫外激发光谱包括两个宽的谱带，峰值分别位于186nm和238nm。前者属于基质晶体的吸收，而后者则是Tb³⁺-O^2-之间的电荷转移态。在161nm真空紫外光激发下，Tb³⁺离子的发射峰主要位于486 nm，545nm，589 nm和623 nm，分别对应于⁵D₄→⁷F_J（J=6，5，4，3），其中以⁵D₄→⁷F₅（545nm）绿光发射为最强。从Ba_2-xSr_xSiO₄：Tb³⁺XRD衍射谱中可以看出，当X=0时，Ba₂SiO₄的XRD衍射谱与JCPDS卡片26-1403符合的较好，随着Sr²⁺掺杂比例的增加，Ba₂SiO₄的衍射峰逐渐减弱，Sr₂SiO₄的衍射峰逐渐增强。监测545nm时，Ba_2-xSr_xSiO₄：Tb³⁺真空紫外激发光谱，位于186nm和238nm附近的吸收峰强度随着x的增大减弱，基质吸收能向低能方向移动。样品Ba_2-xSr_xSiO₄：Tb³⁺在161 nm激发下的发射光谱主要由峰值位于491nm，545nm，589nm，624nm的四个峰组成，分别对应Tb³⁺的⁵D₄-⁷F_J（J=6，5，4，3）跃迁发射，545 nm的发射最强。激活离子相同基质不同，发射的强度也不同，但并未随着Ba/Sr的比率的增加发生规律性变化，Ba_0.4Sr_1.6SiO₄：Tb³⁺的发光强度最大。更多还原

【Abstract】 Now, more and more scholars pay their attention to the phosphors used for PDP （plasma display panel）. Silicate phosphors are promising as candidates of host materials for the new VUV phosphors with various crystal structures and high chemical stability. In this article, it was attempted to prepare rare ion doped M2SiO4 phosphor by the solid-state reaction and their luminescent properties under VUV were investigated.The X-ray powder diffraction data of M₂SiO₄: RE (M=Mg, Sr, Ba, RE=Tm³⁺, Tb³⁺) is in agreement of JCPDS standard card （87-0061, 39-1256, 26-1403）, which indicates that the doped rare ion have little influence on the structure of luminescent host. It indicates that single-phased M₂SiO₄ phosphor can be obtained in such synthesis process.The VUV excitation spectrum under 457nm of M₂SiO₄: Tm³⁺ （M=Mg, Sr, Ba） shows two peaks at about 170nm and 190nm and a broad excitation band from 211nm to 300nm. The former can be assigned to the absorption of the host lattice, which is shifted towards longer wavelengths as the radius of alkali earth ion in M site increases (Mg²⁺＜Sr²⁺＜Ba²⁺). The latter corresponds to the O-Tm³⁺ charge transfer transitions, which is weakened as the radius of alkali earth ion in Re site increases. In the VUV emission spectra of M₂SiO₄: Tm³⁺ （M=Mg, Sr, Ba） under 161nm excitation, The emission peaks at 357nm, 459nm and 478nm are corresponding to ¹D₂→³H₆, ¹D₂→³H₄ and ¹G₄→³H₆ transitions of Tm³⁺, respectively.The VUV excitation spectrum of Ba₂SiO₄: Tb³⁺ under 545nm consists of two broad bands peaked at 186nm and 238nm, respectively. The former can be assigned to the absorption of the host lattice, and the latter corresponds to the O- Tb³⁺ charge transfer transitions, in the vuv emission spectrum of Tb³⁺ under 161nm excitation, the emission peaks at 486 nm, 545 nm, 589 nm and 623 nm corresponds to the ⁵D₄→⁷F_j（J=6, 5, 4, 3） transitions of Tb³⁺. The emission spectra of Ba₂SiO₄: Tb³⁺ have revealed that an intense and sharp （545 nm） green emission from Tb³⁺ （⁵D₄—⁷F₅）.In the XRD parttens of Ba_2-xSr_xSiO₄: Tb³⁺ when X=0, the XRD partten of Ba₂SiO₄: Tb³⁺ accords with the JCPDS standard card of 26-1403. The diffraction peaks of Ba₂SiO₄ are weakened as the value of X increases and the diffraction peaks of Sr2SiO4 is stronger as the value of X increases. In the VUV excitation spectrum of Ba_2-xSr_xSiO₄: Tb³⁺ under 545nm, the absorption intensity of the host lattice, which is about 186nm and 238nm, is weakened as x increases. The absorption peak is shifted towards longer wavelengths. The VUV emission spectrum of Ba_2-xSr_xSiO₄: Tb³⁺ consists of four peaks at 491nm, 545nm, 589nm, 624nm, respectively. They are duo to the transitions of Tb³⁺（⁵D₄-⁷F_j, J=6, 5, 4, 3）, and the excitation of 545nm is the strongest. The emission intensity is different of the change of x in the doped same activation ion, but it doesn’t show the disciplinarian change as the ratio of Ba/Sr increases. The emission intensity of Ba_0.4Sr_1.6SiO₄: Tb³⁺ is the strongest.更多还原