Synthesis, structural and spectroscopic studies on GdBO_3:Yb^(3+)/Tb^(3+)@SiO_2 core-shell nanostructures

The presented study concerned up-converting core/shell type nanomaterials based on lanthanide（Ⅲ） ions, Ln（Ⅲ）, doped orthoborates. The system studied composed of the GdBO3 doped with Yb^3＋/Tb^3＋ luminescent core ensured an effective cooperative sensitization up-conversion, resulting in a bright green luminescence. The silica coating process was performed by a modified St？ber method, which resulted in the formation of core-shell nanostructures, making them suitable for bioapplications. The nanophosphors and nanocomposites were obtained by various methods, such as co-precipitation in the presence of Triton X-100 and micelle synthesis with ethylenediaminetetraacetic acid（EDTA） as organic modifiers/surfactants. The synthesized nanomaterials were characterized with the use of powder X-ray diffraction（XRD）, infrared light absorption with Fourier transform FT-IR spectra, transmission electron microscopy（TEM）, up-conversion emission spectra under IR light, as well as excitation spectra, emission spectra and fluorescence lifetimes under UV light, and their photophysical properties were compared.