双掺Eu^(3+)和Tb^(3+)的下转换β-NaYF_4的合成与发光性能

Synthesis and Luminescence Properties of β-NaYF_4 Doped with Eu^(3+) and Tb^(3+)

采用高温溶剂热法合成了下转换发光材料NaYF4∶Eu3+和NaYF4∶Eu3+,Tb3+,采用X射线衍射(XRD)、场发射扫描电镜(FESEM)、激发(PLE)谱和光致发光(PL)谱对材料的物相结构、形貌特征和发光性质进行了表征和研究,并分析了其发光原理。结果表明:所合成的NaYF4∶Eu3+和NaYF4∶Eu3+,Tb3+为纯六方相晶体,尺寸在100 nm左右;改变Eu3+和Tb3+的掺杂浓度后晶格结构没有发生明显变化,说明Eu3+和Tb3+取代的是Y3+的晶格位置;在394 nm光的激发下,检测到Eu3+在5D0→7F1和5D0→7F2跃迁处的特征发射光,并且可见光强度随着Eu3+离子掺杂浓度的变化而变化。另外Tb3+离子浓度对NaYF4∶Eu3+晶体结构产生了一定的影响,说明掺杂Tb3+离子改变了Eu3+离子所处的配位环境,导致红色发光带增强,而这主要源于电偶极子跃迁的贡献。

Powdered samples NaYF4∶Eu^3＋ and NaYF4∶Eu^3＋,Tb^3＋ are successfully prepared by high temperature solvothermal method.The obtained samples are characterized by X-ray power diffraction（XRD）,field emission scanning electron microscopy（FESEM）,and photoluminescence（PL） spectra.Experiment results revealed that as-prepared NaYF4∶Eu^3＋ and NaYF4∶Eu^3＋,Tb^3＋ crystallized in hexagonal phase without cubic phase,and the size was about 80 nm×100 nm（side length×thickness）.When the doping concentration of Eu^3＋ and Tb^3＋are various,the lattice structure of samples do not change,indicating that the Eu^3＋ and Tb^3＋ ions are completely dissolved in the NaYF4 host lattice by substitution for the Y3＋.The emission from 5D0→7F1（595 nm） and 5D0→7F2（618 nm） of Eu^3＋ ions was observed under excitation of 394 nm light from Xe lamp.The visible light intensity changes with the doping ions of Eu^3＋ concentration and the influence to crystal structure of Tb^3＋ ions concentration have been investigated.These results show that the doping ions of Tb^3＋ change the coordination environment of Eu^3＋,resulting to stronger red emissions,and electric dipole transition occupied the main contribution.