Luminescence of Lu_2O_3:Tm~(3+) nanoparticles

摘要

This paper presents for the first time a comparison between the luminescence properties (viz. emission and excitation spectra, lifetimes, and concentration quenching) of nanocrystalJine and microcrystalline Lu_2O_3:xTm~(3+) (x= 0.1- 5 mol%). The results show that the most important difference between the two size regimes is the higher defect concentration in the nanoparticles. These defects give rise to a broadband emission (λ_(max) = 430 nm), and to partial quenching of the Tm~(3+) emission, in addition to the expected concentration quenching by cross-relaxation between Tm~(3+) ions. The defect concentration seems to be similar in all nanocrystalline samples, so that those with the lowest Tm~(3+) concentrations experience the most pronounced quenching. The nature of these defects is as yet unknown. The local structure around the Tm~(3+) ions is not noticeably different in the two size regimes. No evidence of phonon confinement or quantum size effects was observed in the Tm~(3+) luminescence.