Photoluminescence characteristics and energy transfer between Bi3+ and Eu3+ in Gd2O3: Eu3+, Bi3+ nanophosphors

Bi3+ and Eu3+ codoped cubic Gd2O3 nanocrystals were prepared by the Pechini sol-gel method. Their photoluminescent properties were investigated under ultraviolet light excitation. The introduction of Bi3+ ions broadened the excitation band of Eu3+ emission, of which a new strong band occurred ranging from 320 to 380 nm due to the 6s(2)-> 6s6p transition of Bi3+ ions, implying a very efficient energy transfer from Bi3+ ions to Eu3+ ions. Upon 325 and 355 nm light excitation, the luminescent intensity of Eu3+ ions was remarkably improved by the incorporation of Bi3+ ions. But a significant quenching of Eu3+ emission was observed under 266 nm light excitation when Bi3+ was codoped. The possible energy transfer processes between Bi3+ and Eu3+ were discussed. The decay curves of Eu3+ emission under the excitation of 266 nm pulsed laser were measured and gave further evidence for our discussion.