Site selective spectroscopy in BaYF5:RE3+ (RE = Eu, Sm) nano-glass-ceramics
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Trivalent rare-earth (RE = Eu, Sm) doped transparent nano-glass-ceramics comprising BaYF5 nanocrystals were successfully obtained by appropriate heattreatment of the corresponding precursor sol-gel glasses. Their structural and spectroscopic properties were investigated and compared with those for Eu3+ -dopedBaYF5 nanocrystals prepared by a solvothermal method. X-ray Diffraction, Transmission Electron Microscopy and Energy Dispersive X-ray Spectroscopy measurements confirmed the distribution of BaYF5 nanocrystals in the glass matrix, presenting a cubic phase structure with space group Fm-3m. In order to achieve a further structural characterization, the luminescence properties of the Eu3+ and Sm3+ dopants were also used as sensitive probes. The reduction in the emission intensities of hypersensitive transitions 5D07 F2 and 4G5/26H9/2 for Eu3+ and Sm3+ ions respectively, along with time-resolved measurements, confirm the distribution of a significant fraction of RE ions into the fluoride nanocrystal environment. These results suggest that BaYF5 nano-glass-ceramics doped with Eu3+ or Sm3+ can be considered as potential red-emitting phosphors for the development of white LEDs under near UV excitation.