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Synthesis and optimization of spectroscopic colloidal properties of nanocrystalline oxides doped with lanthanide ions.

The main aim of the research conducted in the framework of the project is synthesis, as well as structural and spectroscopic characterization, of colloidal nanoparticles of yttrium oxide (Y2O3) doped with terbium ions (Tb3 +) and ytterbium (Yb3 +). The phenomenon of conversion of excitation energy up between these ions was rarely investigated due to the relatively low efficiency of cooperative energy transfer as compared to the most commonly used ion, such as Er3 + / Yb3 + or Tm3 + / Yb3 +. In addition, the luminescence intensity of nanoparticles is significantly reduced as compared with the materials at the micro level. It is therefore important to try to improve the performance of emission of quantum materials doped with ions Tb3 + and Yb3 + by modifying the chemical and structural environment of active ions and to monitor their concentration and distribution. By obtaining a relatively high emission intensity of terbium ions and covering the surface of the crystallites with silica or hydrophilic ligand, received nanocrystallites can find a lot of potential biomedical applications such as luminescent marking and biological imaging.

Optimization of the synthesis and spectroscopic properties of nano-sized crystallites of CaF2 and/or MgF2 doped ions Yb3 + and Tm3 +

will last for two years. Its purpose is the appropriate choice of synthesis conditions and the concentration of ions doping selected arrays, thereby enabling to obtain efficient luminophores excited by infrared light, which convert the energy up.

Both calcium and magnesium fluoride are interesting materials that may serve as a template for the doping with lanthanide ions. Calcium fluoride CaF2 is a well known material having a relatively low lattice vibration energy. Magnesium fluoride MgF2, however, is by far one of the least studied nanocrystalline fluoride. Ions of calcium and magnesium included in the array are nontoxic and their ionic radius is close to the ionic radius of the lanthanide ion, thus they can easily be incorporated into the structure of these fluorides.

In biological applications, thulium ion emission in the near infrared (at 800 nm) due to low-energy excitation of 980 nm radiation is very important, as both the radiation energy are within the range of, so called, optical window of the skin. Within this range, the radiation can penetrate to a significant depth of tissues and biological materials. This makes materials doped with Yb3 + / Tm3 + competitive with conventional organic dyes and quantum dots, which require excitation with radiation of higher energy.

Posted by Wrocławskie Centrum Badań EIT+, Posted on 28.08.2015