Eu^(3+)掺杂TiO_2纳米晶的制备及光致发光研究

Preparation and Photoluminescence of Europium-Doped Titania Nanocrystals

以Ti(O BU) 4为前驱体 ,采用溶胶 凝胶法制备了掺杂Eu3+ 离子的TiO2 纳米晶。分别以X射线衍射 (XRD)和光致发光 (PL)光谱对不同温度烧结下的样品进行了表征。XRD分析表明 ,由于Eu3+ 掺杂浓度低 ,纳米晶呈现单一的锐钛矿相 ,Eu3+ 可能主要位于纳米TiO2 颗粒的表面。PL分析表明 ,当用紫外 可见光 380 ,395 ,41 5和 468nm对掺杂Eu3+ 的TiO2 纳米晶进行激发时 ,都发射了一系列PL信号 ,其中用 468nm激发效率最高 ,380nm激发效率几乎为 0 ,也就是说 ,468nm代替通常的 395nm成为最灵敏的激发线 ;这些PL发光峰分别对应着Eu3+ 的5D0 →7FJ(0～ 4)跃迁 ,其中以5D0 →7F2 跃迁的 61 6nm的纯红色发光效率最高。从不同温度热处理TiO2 ∶Eu3+ 纳米晶的激发光谱看出 ,Eu3+ 的特征发射来自基质带间吸收 (380nm附近处 )的有效激发都很弱。

Europium-doped titania nanocrystals were prepared by sol-gel technique using Ti(O-BU)_4 as the precursor and the samples sintered at different temperature were characterized by XRD and PL spectra. Due to a small concentration doped with Eu 3+, the XRD results show pure anatase structure of titania, and Eu 3+ ions are possibly located on the surfaces of titania nanocrystals. At room temperature (RT), the photoluminescence spectra were measured. The results show a series of PL signals when europium-doped titania nanocrystals are excited under Uv-vis light of 380, 395, 415 and 468 nm, and excitation efficiency is highest at 468 nm, and excitation efficiency is nealy 0 at 380 nm, that is to say, 468 nm is most sensitive excitation line, therefore, the excitation source is extended from ultraviolet to visible light, which is very beneficial to luminescence. These PL peaks correspond to the transitions of 5D_0→ 7F_J (0～4) of Eu 3+ respectively, and the pure red luminescence of 616 nm at the transitions of 5D_0→ 7F_2 is strongest. The excitation spectra show that the efficient excitation is weak for the host band gap absorption (around 380 nm).