Enhanced and tuneable green and red emissions in RE3+ doped LaF3 nanocrystals

RE3+ (Ce3+, Gd3+, Tb3+, Eu3+)-doped LaF3 silica nano-glass-ceramics (nGCs) were obtained by thermal treatment of precursor sol-gel glasses. The precipitation and distribution of spherical LaF3 nanocrystals (NCs) with sizes around 8.5 nm in the silica matrix were confirmed by X-ray diffraction patterns, transmission electron microscope images and energy dispersive X-ray spectroscopy measurements. Very efficient energy transfer mechanisms from Ce3+ to Tb3+ or Eu3+ ions, mediated by Gd3+ ions through the Ce3+→(Gd3+)n→(Tb3+/Eu3+) scheme, were observed in Ce3+-Gd3+-Tb3+ and Ce3+-Gd3+-Eu3+ co-doped nGCs, yielding intense green and red emissions, respectively. Moreover, simultaneous and tuneable Ce3+ sensitized Tb3+ and Eu3+ emissions were obtained in Ce3+-Gd3+-Tb3+-Eu3+ co-doped nGCs by varying the content of Tb3+ and Eu3+ ions, and the corresponding energy transfer mechanisms were analysed. Results suggest these nGCs as potential UV to VIS converters in the field of lighting and display. •RE3+-doped nano-glass-ceramics with hexagonal LaF3 nanocrystals were obtained.•Under Ce3+ excitation, enhanced Tb3+ green and Eu3+ red emissions are shown.•Energy transfer and metal-metal-charge-transfer mechanisms were evidenced.•Results suggest potential applications as UV-VIS converters in the field of lighting.