info:eu-repo/semantics/article
Near UV-Blue Excitable Green-Emitting Nanocrystalline Oxide
Autor
Carlos Eduardo Rodriguez Garcia
Institución
Resumen
"Green-emitting Eu-activated powders were produced by a two-stage method consisting of pressure-assisted combustion synthesis and postannealing in ammonia. The as-synthesized powders exhibited a red photoluminescence (PL) peak located at λ = 616 nm when excited with λ = 395 nm UV. This emission peak corresponds to the <sup>5</sup>D<sub>0</sub> → <sup>7</sup>F<sub>2</sub> transition in Eu<sup>3+</sup>. After annealing in ammonia, the PL emission changed to an intense broad-band peak centered at λ = 500 nm, most likely produced by 4f<sup>6</sup>5d<sup>1</sup> → 4f<sup>7</sup> electronic transitions in Eu<sup>2+</sup>. This green-emitting phosphor has excitation band in the near UV-blue region (λ = 300–450 nm). Xray diffraction analysis reveals mainly the orthorhombic EuAlO<sub>3</sub> and Al<sub>2</sup>O<sub>3</sub> phases. Transmission electron microscopy observations showed that the grains are formed by faceted nanocrystals (∼4 nm) of polygonal shape. The excellent excitation and emission properties make these powders very promising to be used as phosphors in UV solid-state diodes coupled to activate white-emitting lamps."