Ultraviolet fluorescence of the Ce3+/Gd3+ co-doped NaYF4 nanocrystals

In this paper, Ce3+/Gd3+ co-doped NaYF4 nanocrystals were prepared via a traditional hydrothermal method using oleic acid as the stabilizing agent. Under 250 nm excitation, down-conversion emissions centered at 305 and 311 nm were observed in NaYF4:Ce3+/Gd3+ nanocrystals. The down-conversion emissions were attributed to the 6P7/2, 6P5/2→8S7/2 transitions of Gd3+ ions. The energy transfer from Ce3+ to Gd3+ plays a crucial role in populating the excited energy levels of Gd3+ ions.