Fabrication And Photoluminescent Properties Of Rare-earth Eu Ion Doped Nanosized Luminescent Materials

Compare with their corresponding bulk phases, nanoscale rare earth luminescent materials have come forth a lot new luminescent phenomena. Investigating and understanding these materials is not only of academic interest but also of technological importance for advanced phosphor applications. Eu-doped nanoscale rare earth luminescent materials have been investigated in this dissertation, the significant results achieved in this dissertation are given as follows:(1) La₂O₃:Eu³⁺ nanoparticles and hexagonal type-â…¡La₂O₂CO₃:Eu³⁺ nanospheres were prepared through the hydrothermal reaction followed by a subsequent calcination at 873K. The shape, size and species of the as-obtained samples can be tuned effectively by controlling the volume ratio of ethylene glycol (EG) to water (W) in solution. When EG > W (by volume), the precipitate was amorphous lanthanum compounds nanorod, which turned into La₂O₃:Eu³⁺ nanoparticle after continuously heating. When EG < W (by volume), the precursor was LaCO₃OH:Eu³⁺. The result sample was uniform La₂O₂CO₃:Eu³⁺ nanosphere. The possible formation mechanism of selective synthesis of the lanthanum nanoparticles was discussed in detail. Furthermore, La₂O₃:Eu³⁺ and La₂O₂CO₃:Eu³⁺ we gained have remarkable stability on CO₂ in the air.(2) Yellow/orange-emitting Ba₂Mg(PO₄)₂: Eu²⁺ phosphors were successfully prepared by Pechini sol-gel method. The emission spectra of Ba_2-xMg(PO₄)₂: xEu²⁺ phosphors are featured by one broad band centered at ca. 560 nm, which are assigned to the 4f⁶5d¹â†'4f⁷ transitions of the Eu²⁺. With increasing the amount of doping Eu²⁺ up to 4 % (by mol) the emission peak intensity increased. Eu²⁺ from Ba₂Mg(PO₄)₂: Eu²⁺ phosphors occupies two different lattice sites by replacing Ba²⁺. With increasing the amount of doping Eu²⁺, the ability of Eu²⁺ entering the first lattice site of Ba₂Mg(PO₄)₂ improved.