Hydrothermal synthesis, energy transfer and luminescence enhancement of rhombohedral LaOF: Sm3+-Eu3+ nanoparticles

Sm3+, Eu3+ sole- and co-doped LaOF nanoparticles with rhombohedral crystal structure were synthesized via hydrothermal method followed a post-annealing process. The samples were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and photoluminescence techniques. The XRD result shows that the samples exhibit a rhombohedral phase in crystal structure. For Sm3+, Eu3+ co-doped LaOF nanoparticles, pumping Sm3+ to its excited (4)G(9/2) level by 442 nm laser, the intense characteristic emissions of Eu3+ ion were observed, indicating that the energy transfer from Sm3+ to Eu3+ ions occurred. The intensities of Eu3+ emissions due to energy transfer increased with increasing the doping concentration of Eu(3+ )acceptor. The enhancement of Eu3+ red-light emission at 610 nm through co-doping Sm3+ ion was also observed when the Sm3+, Eu(3+ )co-doped LaOF nanoparticles excited by 532 nm laser. The optimum concentration of Sm3+ co-dopant is 0.5 mol% for enhancing the strongest luminescence of Eu3+ red-light.