Influence of Gd 3+ on the Optical Properties of Dy 3+ -Activated CaF 2 Single Crystal for White LED Application

The spectroscopic properties of 0.6%Dy:Ca1−xGdxF2+x (x = 0.003, 0.006, 0.012, 0.03) crystals were investigated and compared. The energy transfer process between Gd3+ and Dy3+ was also studied. Increasing the proportions of Gd3+ ions could enhance the visible emission intensity significantly for the blue (478 nm) and yellow (573 nm) emissions; the intensity of the yellow emission was especially increased to be 77 times greater than the 0.6%Dy:CaF2 crystal. Gd3+ ions were not only used to enhance the emission intensity, but also played an important role in regulating the local lattice structure of Dy3+ ions. As a consequence, tunable white-light emission colors could be obtained by adjusting the doping concentration of Gd3+ ions.