Bright luminescence of Gd3+ sensitized RE3+-doped SiO2-BaGdF5 glass-ceramics for UV-LEDs colour conversion
RE-doped (Eu3+, Sm3+, Dy3+ or Tb3+) nano-glass-ceramics containing BaGdF5 nanocrystals, have been successfully obtained under thermal treatment of precursor sol-gel glasses. X-ray diffraction, high-resolution transmission electron microscope images and energy dispersive X-ray spectroscopy measurements confirmed the precipitation and distribution of cubic BaGdF5 nanocrystals (around 10 nm in size) in the glass matrix. The luminescent properties, via excitation and emission spectra along with decay curves, were studied. In order to complete the structural analysis, the luminescent features of Eu3+ and Sm3+ ions were also used as sensitive probes, confirming the distribution of a significant fraction of dopant ions into the fluoride nanocrystalline environment. Intense visible emissions were obtained through efficient energy transfer from Gd3+ to RE ions, which leads to consider these materials as potential emitting phosphors for colour converted UV LEDs.