Combustion synthesis and up-conversion luminescence of La2O2S:Er3+,Yb3+ nanophosphors
Résumé
La2O2S:Er3+,Yb3+ nanocryst. up-converting phosphors were synthesized by a combustion method at low temp., using ethanol as pre-ignition fuel and thioacetamide as sulfurizing agent and org. fuel. The phosphors were characterized by powder X-ray diffractometry, SEM, UV/Vis/NIR spectroscopy and fluorescence spectroscopy. Pure and well-crystd. La2O2S:Er3+,Yb3+ nanoparticles, of the order of 50-200 nm, are obtained after a post-treatment in a H2S/N2 flow for 2 h at 1000 °C. The efficient energy transfer from Yb3+ to Er3+ results in a strong up-conversion upon excitation at 980 nm. The emission spectra show the intense green emissions corresponding to the (2H11/2, 4S3/2)→4I15/2 transitions and a red emission corresponding to the 4F9/2→4I15/2 transition. Addnl., within the investigated co-doping concns., no significant concn. quenching effect and back energy transfer from Er3+ to Yb3+ were evidenced. This research highlights the influence of the sulfurization treatment on the purity/crystallinity/morphol. of the nanocrystals and the luminescence efficiency.
Domaines
Matériaux
Origine : Fichiers produits par l'(les) auteur(s)
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