摘要
采用溶胶-凝胶(sol-gel)法制备了Eu掺杂的SiO2干凝胶,分别用光致发光(PL)光谱、透射电镜(TEM)、扫描电镜(SEM)、红外吸收(IR)谱等分析手段对样品进行了表征,研究了SiO2的基质中Eu3+、Eu2+的发光特性以及退火温度对发射光谱的影响,并对其发光机理进行了分析。结果表明,样品掺杂均匀,颗粒尺寸大约在50～80 nm,硼(B)离子进入SiO2网格,成为了基质的一部分,改变了基质的网络结构。当采用258 nm激发样品时,随着退火温度的升高,红光发射强度先增强后减弱。对于经800℃退火处理的样品红光发射最强,出现了576 nm(5D0→7F0),620 nm(5D0→7F2),658 nm(5D0→7F3)3条谱线,其中主峰位于620 nm红光发射,对应于Eu3+离子的5D0→7F2超灵敏跃迁,进一步说明B离子参与到基质中,形成了Si—O—B键,导致Eu3+离子所处配位环境的对称性降低,从而有利于Eu3+离子的特征发射;当采用271 nm激发样品时,随着退火温度的升高,蓝光发射强度先增强后减弱,经850℃退火的样品400～500 nm蓝光发射最强,归属于Eu2+的5d→4f的跃迁发射,证明在铝离子(Al3+)存在的情形下,在高温退火过程中Al3+部分取代Si4+形成AlO4-基团,掺杂Eu3+填补AlO4-基团附近的空位,增加了Eu3+周围的AlO4-四面体中氧原子的电子给予能力,使得Eu3+还原成Eu2+,从而得到了较强的蓝光发射。但是,当退火温度达到900℃时,由于稀土离子发生位置的迁移形成团簇红光和蓝光都明显地降低。
Eu-doped SiO2 matrix xerogels were prepared by sol-gel process. The samples were characterized with photoluminescence spectrum, transmission electron microscope （TEM）, scanning electron microscope （SEM） and infrared absorption （IR） spectrum etc. The influence of annealing temperature on luminescent properties of the xerogels as well as influence of Eu^3＋ , Eu^2＋ doped ions on the luminescence of the the xero- gels were presented. The mechanism of luminescence was studied. For the uniform doping samples, particle size was about 50 -80 nm. The network structure of the matrix was changed because of boron（B） doping. Ex cited at 258 nm, with the increase of annealing temperature, the intensity of the red light emission at first en- hanced, and then weakening. The red luminescent intensity of the sample annealed at 800 ℃ was the stron- gest. The spectral peaks are at 576 nm（^5D0→^7F0） , 620 nm（^5D0→^7F2）and 658 nm（^5D0→^7F3） , the strong red Eu^3＋ emission of the samples centered at 620 nm was due to the transitions of ^5D0→^7F2 of Eu^3＋. Further, this detailed to B into the matrix, formed Si--O--B bonds, leading to Eu^3＋ ions coordination environment with the lower symmetry, which is beneficial to the characteristic emission of Eu^3＋. In the presence of Al^3＋ and excited at 271 nm, the blue luminescent intensity of the sample annealed at 850℃ reached the strongest, a strong blue Eu^2＋ emission band centered at 400 - 500 nm was observed, which were due to the transitions of 5d→4f of Eu^2＋. The Al^3＋ ions can increase the electron donation ability of oxygen in AlO4^- tetrahedron around Eu^3＋ and reduced Eu^3 ＋ to Eu^2＋. During the annealing process the rare earth ions may imigrate and form clus- ters. Therefore, the red emission of Eu^3＋ and the blue emission of Eu^2＋ were obviously reduced as annealing temperature is up to 900 ℃.
出处
《发光学报》
EI
CAS
CSCD
北大核心
2009年第2期247-251,共5页
Chinese Journal of Luminescence
基金
国家自然科学基金(20876125)
西北大学研究生自主创新项目(07YZZ019)
陕西省教育厅科技计划(08JK451)资助项目
