Abstract

NaYF4 nanocrystals doped with Eu3+ ions have been prepared by hydrothermal method at 180 oC for 24 hours, then they were treated at 500 oC in air. The result of XRD showed NaYF4 nanocrystals exitsted hexagonal β phase. The structure of NaYF4 was not affected by the presence of rare earth ion. Under excitation at 395 nm, the PL spectra have emission bands at 592, 615 and 689–695 nm attributed to 5Do?7F1, 5Do?7F2 and 5Do?7F3 transitions of Eu3+ ion. NaYF4:Eu NPs possess a high security properties upon an excitation at 254 nm.