Infrared-laser precipitation of Dy3+-Yb3+ codoped SrF2 nanocrystals in glass and upconversion luminescence

Abstract Oxyfluoride glass-ceramics containing SrF 2 nanocrystals have been prepared by a CO 2 laser treatment on the glass prepared by high temperature melt quenching. The optimized scan speed and laser power produced nanocrystals with sizes of ~10 nm. Energy dispersive spectroscopy mapping analysis showed that Dy 3+ and Yb 3+ ions are highly populated inside the SrF 2 nanocrystals. We also report a substantially enhanced down-converted visible emission from the 4F9/2 state of Dy3+ ions, including some violet emissions from the higher energy states under 365 nm excitation in the glass-ceramics, as compared to the as-made glass. Moreover, 980 nm laser diode excitation produced strong green and red emissions from the 4 I 15/2 state and blue and yellow emissions from the 4 F 9/2 state. A model has been proposed to interpret the upconversion emissions through the multistep-excitation of Dy 3+ ions and energy transfers from, efficient sensitizers, Yb 3+ ions to Dy 3+ ions.