Effect of Lu3+ on optical properties of Er3+/Yb3+ co-doped oxyfluoride glass-ceramics containing Y5O4F7 nanocrystals.

Local symmetry of crystal field is crucial for optical temperature sensitivity that based on the thermal couple levels of rare earth ions. In this work, Lu3+ ions were introduced to alter the local environment of Er3+ ions in oxyfluoride glass-ceramics. X-ray diffraction patterns and transmission electron microscope images show that Y 5 O 4 F 7 nanocrystals are precipitated in glass-ceramics. Incorporation of rare-earth ions into the Y 5 O 4 F 7 nanocrystals is confirmed by absorption and electron energy loss spectra. The Judd-Ofelt (J-O) theory analysis reveals that local symmetry of the crystal field around Er3+ decreasing due to Lu3+ co-doping. Temperature sensing property of the Y 5 O 4 F 7 : Er3+/Yb3+/Lu3+ nanocrystal incorporated glass-ceramic was investigated, and the optimal relative temperature sensitivity S R reaches 1.50 % K−1 in 0.25 mol.% Lu3+ doped specimen. Results show that the moderate addition of Lu3+ can improve the temperature sensitivity of glass-ceramic containing Y 5 O 4 F 7 :Er3+/Yb3+ nanocrystals, which provide a promising avenue for optical temperature sensing. [ABSTRACT FROM AUTHOR]