【摘要】 表面缺陷会使纳米材料的发光中心产生严重的猝灭,而适当厚度的同质包覆层会减少其猝灭。本文利用共沉淀法合成了LaF3∶Eu3+纳米颗粒和LaF3∶Eu3+/LaF3核壳结构纳米颗粒,研究了颗粒的晶体结构、形貌以及不同壳层厚度对发光性能的影响。研究发现:LaF3∶Eu3+核心和LaF3∶Eu3+/LaF3核壳结构均为六方结构。包覆同质壳层可以提高稀土离子的发光性能,包覆厚度的不同导致LaF3∶Eu3+/LaF3核壳结构的荧光强度与衰减时间均发生改变。其原因是未掺杂的LaF3壳层可以将发光中心Eu3+离子与LaF3∶Eu3+核心的表面隔离,进而减少表面对发光中心的猝灭,提高材料的发光性能。这种修饰作用与壳层厚度相关。更多还原

【Abstract】 Coating the nanoparticles with a homogeneous shell is a feasible strategy to reduce energy losses on the nanoparticle surface. Eu3 +doped hexagonal LaF3nanoparticles with a mean size of 7 ~ 8 nm were prepared by co-precipitation method. After coating the LaF3∶ Eu3 +core particles with the undoped LaF3,the enhancement of Eu3 +emission in LaF3∶ Eu3 +/ LaF3core-shell nanoparticles was discovered. In comparison with the LaF3∶ Eu3 +core,the luminescence lifetime of Eu3 +emission in core-shell nanoparticles was increased. The decay curves of LaF3∶ Eu3 +/ LaF3core / shell nanoparticles with different thickness had also been studied. The increase of the luminescence lifetime of Eu3 +emission resulted from the effective shielding of the luminescence center Eu3 +ions from LaF3∶ Eu3 +core,the quenching at or near the surface of the nanoparticles was reduced.更多还原