Tuning red-green-white up-conversion color in nano NaYF4:Er/Yb phosphor

The possibility of tuning between red, green and broadband white color of up-conversion was demonstrated in thermally 450 °C treated Yb/Er co-doped nano NaYF 4 phosphor. The color variability was studied by means of power dependence of luminescence, which exhibited unusual behavior. Large hysteresis, as well as discrepancy from a power law indicated the important role the increased heating played during the up-conversion in nano-sized materials.