A comparison of morphology, structure and optical properties of ultrasmall, small and core-shell up-converting NaYF4/NaGdF4 nanocrystals co-doped with Tm3+ and Yb3+ ions

作者：Wawrzynczyk D; Nyk M; Bednarkiewicz A; Strek W; Samoc M^*

来源：Journal of Luminescence, 2013, 133: 138-144.

DOI：10.1016/j.jlumin.2011.09.035

• NaYF4/NaGdF4 nanoparticles
• Up-conversion luminescence
• Core-shell nanostructures

Synthesis, crystal structure, morphology and optical properties of three various NaYF4 nanoparticle systems co-doped with Tm3+ and Yb3+ ions have been investigated. Characterization of ultrasmall (size similar to 8 nm), small (similar to 25 nm) NaYF4:2%T3+, 20%Yb3+ nanoparticles and core-shell structures (NaYF4:20%Yb3+-NaGdF4:2%Tm3+) synthesized according to two different protocols is presented. We have found that the up-conversion luminescence is strongly influenced by the nanoparticle size, internal structure and spatial distribution of active Tm3+ ions. Further spectroscopic studies revealed significant fluorescence rise and decay time lengthening of the (1)G(4) energy level of Tm3+ ions in NaYF4:20%Yb3+-NaGdF4:2%Tm3+ core-shell nanoparticles. The formation of the core-shell structures was proven indirectly through the average crystalline size increase between the bare core and coreshell nanoparticles, the observed changes in EDX composition as well as variation of Tm3+ ions luminescence properties.

• 出版日期2013-1