Enhanced up-conversion luminescence efficiency of heterogeneous hetero-phase alpha-NaLuF4:Yb/Er@ beta-NaYF4:Yb core-shell structure nanocrystals

摘要

The heterogeneous hetero-phase alpha-NaLuF4:Yb/Er@ beta-NaYF4:Yb core-shell structure nanocrystals with small particle size can be induced via heterogeneous core induction successfully. And the crystal phase of core-shell structure nanocrystals can be greatly affected through adjusting the amount ratio of core to shell. The mutual induction of phase transformation between heterogeneous core and shell is investigated. Under the 980 nm laser excitation, the luminescence enhancement ability of heterogeneous hetero-phase alpha-NaLuF4:Yb/Er@ beta-NaYF4:Yb core-shell structure nanocrystals is much higher than that of the heterogeneous homo-phase core-shell structure nanocrystals synthesized at the same condition. The up-conversion luminescence efficiency of heterogeneous hetero-phase alpha-NaLuF4:Yb/Er@ beta-NaYF4:Yb core-shell structure nanocrystals is highest when the Yb3+ ion concentration in core and shell is the same. In addition, the population of up-conversion red emission can be influenced by enhancing the cross relaxation process when the concentration of Yb3+ ions in shell layer is increased. These results deepen the understanding of the growth and energy transfer process of the core-shell structure nanocrystals and make the heterogeneous hetero-phase alpha-NaLuF4:Yb/Er@ beta-NaYF4:Yb nanocrystals suitable for using in the biomedicine application. (C) 2020 Elsevier B.V. All rights reserved.