Adjustable up-conversion luminescence color in rare earth co-doped transparent oxyfluoride nano-glass-ceramics

Transparent oxyfluoride nano-glass-ceramics with highly efficient up-conversion and adjustable color luminescence were developed in the 28SiO2 x 17Al2O3 28PbF2 x 22CdF2 x 0.1NdF3 x xYbF3 x yHoF3 zTmF3 x (4.9 - x - y - z)GdF3 composition, in mol%. X-ray diffraction and transmission electron microscopy measurements revealed that heat treatments of the oxyfluoride glasses cause the homogeneous precipitation of rare-earth ions co-doped fluorite-type Pb(x)Cd1-xF2 nanocrystals of about 10 nm in diameter in the glass matrix. Under single 808 nm laser excitation, intense red, green and blue up-conversion luminescences were simultaneously observed in these transparent nano-glass-ceramics owing to the successive energy transfer from Nd3+ ions to Ho3+ and Tm3+ via Yb3+ ions. Various colors of luminescence, including bright perfect white light, can be tuned by adjusting the concentrations of the Tm3+ ions in the material. A possible energy transfer process and up-conversion luminescence mechanism in the nano-glass-ceramics are proposed and discussed.