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RESEARCH PRODUCT

Mechanism for energy transfer processes between Ce3+ and Tb3+ in LaPO4:Ce,Tb nanocrystals by time-resolved luminescence spectroscopy

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The energy transfer mechanisms between Ce 3+ and Tb 3+ in LaPO 4 :Ce,Tb nanocrystals have been studied by means of time-resolved luminescence spectroscopy in a wide temperature range (10-300K). Special attention was paid to detailed comparative analysis of both rise and decay emission components of both Ce 3+ and Tb 3+ . Surprisingly, a relatively slow rise (several microseconds) of Tb 3+ emission under 266-nm laser excitation was detected, which corresponds to the 4f-5d transition of Ce 3+ in LaPO 4 . It was shown that this rise of Tb 3+ emission could not have arisen due to relaxation of Ce 3+ ions, whose excited state has a lifetime of about 20ns. It was demonstrated that the generally accepted concept of a resonant energy transfer from Ce 3+ to Tb 3+ in LaPO 4 could not explain the time-resolved luminescence characteristics as well as the observed temperature dependence. Hence, a new concept of the energy transfer process from Ce 3+ to Tb 3+ in LaPO 4 via host lattice states was suggested and elucidated by proposing several possible models.