Title of article :
Influence of Li+ doping on up-conversion and structural properties of Yb3+/Tm3+-doped cubic NaYF4 nanocrystals
Author/Authors :
Ma?gorzata Misiak، نويسنده , , Bart?omiej Cichy، نويسنده , , Artur Bednarkiewicz، نويسنده , , Wieslaw Strek، نويسنده ,
Issue Information :
روزنامه با شماره پیاپی سال 2014
Pages :
7
From page :
956
To page :
962
Abstract :
The impact of Li+ doping on luminescence and structural properties of cubic NaYF4:Yb3+/Tm3+ colloidal nanocrystals was studied. The Yb3+/Tm3+ co-doped samples demonstrated significant red to blue emission ratio changes and high concentration quenching. By substituting Na+ with smaller Li+ ions within NaYF4 lattice, we expected to induce distortions in order to prevent the concentration quenching process, which is responsible for decrease of the luminescence intensity. The results indicated that the substitution of sodium ions by Li+ did not enhance Tm3+ up-conversion emission significantly in α-NaYF4:Yb3+/Tm3+. However, the influence of lithium ions on luminescence was not entirely the same in the case of 2% Tm3+ and 0.1% Tm3+ doped samples. The slight up-conversion intensity enhancement in the case of samples doped with 2% Tm3+ could result from the increase in the crystallites size and changes in the surface to volume ratio. The observed increase in lattice parameter and thus the increased distance between thulium ions in the lattice might also result in breaking apart of pairs responsible for cross-relaxation processes. Interestingly, in the 0.1% Tm3+ co-doped samples, initial luminescence intensity decrease followed by increase correlated with Li+ substitution was observed. Due to the existence of two different sites for incorporation of lithium ions into the host lattice, the changes in lattice parameters and resulting optical properties are not straightforward functions of variable amount of Li+.
Keywords :
nanocrystals , Cubic NaYF4 , up-conversion luminescence , Li+ co-doping
Journal title :
Journal of Luminescence
Serial Year :
2014
Journal title :
Journal of Luminescence
Record number :
1263509
Link To Document :
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