Structural and optical investigation of colloidal Ln3+/Yb3+ co-doped KY3F10 nanocrystals

We report for the first time the synthesis of colloidal Ln(3+)/Yb(3+) co-doped KY(3)F(10) nanocrystals (L(n) = Er or Eu) via thermal decomposition. The transmission electron microscopy (TEM) studies indicated that the average size of the nanocrystals was approximately 15 nm. The nanocrystals crystallized in the cubic Fm (3) over barm space group as confirmed by Rietveld refinement of the X-ray powder diffraction patterns and by electron diffraction analysis. The Eu(3+) ion was used as a spectroscopic probe and its emission spectrum in colloidal KY(3)F(10) nanocrystals showed that the lanthanide ions replaces Y(3+) in the lattice structure. When co-doped with Er(3+)/Yb(3+), colloidal KY(3)F(10) nanocrystals exhibited visible (green and red) upconversion emissions following 978 nm excitation with a near-infrared (NIR) diode laser. Power dependence studies indicated that a two-photon energy transfer upconversion process was responsible for the NIR-to-visible upconversion.