【摘要】 通过水热法合成出Ce3+和Tb3+共激活的LaPO4纳米线,并同相应的微米棒进行了比较。研究了其荧光光谱和动力学过程。结果表明纳米线和微米棒的晶体结构均为单斜相。在单掺杂Ce3+和Tb3+的材料中,微米棒的发光强度与纳米线相比稍有提高,但在共掺杂的纳米线样品中对应Ce3+的激发,Tb3+的5D4→7F5绿光发射比微米棒提高了3～5倍。通过动力学研究,纳米线中Ce3+和Tb3+的电子跃迁速率与微米棒对比没有显著的提高,且Ce3+→Tb3+的能量传递速率降低了3倍。Tb3+的5D3能级衰减包括两个过程:快过程和慢过程。纳米线以慢过程为主,而微米棒以快过程为主。我们认为慢过程对应5D3→5D4的弛豫,快过程对应5D3向其他缺陷能级的跃迁。因此共掺杂纳米线中强度的提高被归因于在纳米线中更多的边界阻碍而引起在高于5D4的激发态能级上损失的能量更少。更多还原

【Abstract】 To develop the Ce³⁺ and Tb³⁺ co-activated LaPO₄ nanowires （NWs） green phosphors, a significant question should be considered: In one-dimensional NWs, how do the electronic transition and the energy transfer processes between Ce³⁺ and Tb³⁺ change in comparison with the bulk crystals? To our knowledge, there is no report on this topic until now. In practice, the studies on energy transfer processes between different rare earth centers in NWs are quite rare, too. Recently, we successfully fabricated Ce³⁺-activated, Tb³⁺-activated and Ce³⁺/Tb³⁺ co-activated LaPO₄ NWs as well as micrometer rods （MRs） by the hydrothermal method. Their fluorescent spectra and dynamics were studied in contrast to the MRs. The results indicate that the structure of both the samples belongs to monoclinic phase. The intensity of Ce³⁺ or Tb³⁺ in MRs for singly doped samples increased a little in contrast to NWs. It is important that the intensity of Tb³⁺ in NWs corresponding to Ce³⁺ excitation increased 3⁵ times than that in MRs. The extinction concentration of Ce³⁺ and Tb³⁺ in NWs increased than that in MRs. The electronic transition rate of Ce³⁺ and Tb³⁺ in NWs had only a little variation in comparison with that in MRs, and the energy transfer rate and efficiency of Ce³⁺→Tb³⁺ in NWs reduced. Surprisingly, the brightness for the ⁵D₄→⁷F₅ green emissions of Tb³⁺ via energy transfer of Ce³⁺→Tb³⁺ in NWs increased several times than that in MRs. To reveal the origins of above phenomenon, the ⁵D₃ level decay of Tb³⁺ was measured. The results indicated that the decay curve included two proponents: a fast and a slow process. The slow proponent was dominant in NWs and fast proponent was dominant in MRs. We suggested that the slow proponent corresponded to the transition of ⁵D₃→⁵D₄ and fast proponent corres-（ponded） to the relaxation from ⁵D₃ to other defect centers. The increased intensity of Tb³⁺ in NWs via energy transfer excitation was attributed to the decreased energy loss in the excited states being higher than ⁵D₄ due to the hindrance of the boundary.更多还原