Ultraviolet upconversion luminescence of Gd3+ and Eu3+ in nano-structured glass ceramics

Highlights: ► Ultraviolet upconversion emissions of Eu3+ and Gd3+ are rarely studied. ► Nanostructured glass ceramic is developed as a host for ultraviolet upconversion. ► Ultraviolet upconversion signal are found greatly enhanced after crystallization. ► It is promising for fabricating novel ultraviolet upconversion lasers. -- Abstract: Ultraviolet multiphoton upconversion emissions of Eu3+ (5H3–7, 5G2–6, 5L6 → 7F0) and Gd3+ (6IJ, 6PJ → 8S7/2) are studied in the Eu3+ (or Gd3+) doped SiO2–Al2O3–NaF–YF3 precursor glasses and glass ceramics containing β-YF3 nanocrystals, under continuous-wavelength 976 nm laser pumping. It is experimentally demonstrated that energy transfer from Yb3+ to Tm3+, then further to Eu3+ or Gd3+ is responsible for the upconversion process. Compared to those in the precursor glasses, the upconversion emission intensities in the glass ceramics are greatly enhanced, owing to the participation of rare earth ions into the low-phonon-energy environment of β-YF3 nanocrystals. Hopefully, the studied glass ceramics may find potential applications in the field of ultraviolet solid-state lasers.