Energy transfer mechanism and luminescence properties of color tunable LaPO4:Tm,Eu phosphor

The energy transfer mechanism between Tm3+ and Eu3+ ions in the phosphate phosphor was investigated. The addition of Eu facilitated the incorporation of O atoms into the LaPO4:Tm,Eu phosphor lattice, which induced changes in its ligand field and energy absorption. Excitation energy was transferred from Tm3+ to Eu3+ ions by the mechanism of dipole dipole interaction. The increase in Eu concentration increased the probability of energy transfer between Tm3+ and Eu3+ as well as the electron transition probabilities in Eu3+; a color-tunable emission was observed through variation in the Eu concentration. The highest energy transfer efficiency of Tm3+ Eu3+ was approximately 93%. The critical distance, for energy transfer, between Tm3+ and Eu3+, was 14.5 angstrom. The luminescence of the phosphor declined with a double-exponential mechanism. The decay time decreased as the Eu doping concentration was increased. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.