Enhanced red-emission of β-NaYF4:Er3+/Eu3+ microparticles via energy transfer with La3+ doping

In this paper hexagonal trivalent lanthanide ions (Ln(3+)) doped beta-NaYF4 microparticles were synthesized by a facile hydrothermal method. The structure, morphology and composition of the microparticles were confirmed by XRD, SEM, EDS. Multicolor luminescence was observed. The up-conversion(UC) and down conversion emission intensity of beta-NaYF4:Ln(3+) (Ln(3+)=Er3+, Eu3+) microparticles and the red-emission of beta-NaYF4:Er3+/Eu3+ microparticles were increased. The La3+ ions doped the samples enhancing energy transfer between the Ln(3+) ions by altering the crystal field symmetry around Ln(3+) is described.