Structural, photoluminescent properties and Judd-Ofelt analysis of Eu3+-activated CaF2 nanocubes
Eu3þ-doped CaF2 nanocubes with variable europium concentration, [Eu3þ] ¼ 0, 0.6, 1.3, 1.7, 2.2 and 5.4 mol%, have been synthesized by a direct precipitation route. It has been found that, within this concentration range, the nanoparticles present the fluoride-type crystalline structure and the chara...
| Autores: | , , , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2020 |
| País: | España |
| Institución: | Universidad Autónoma de Madrid |
| Repositorio: | Biblos-e Archivo. Repositorio Institucional de la UAM |
| Idioma: | inglés |
| OAI Identifier: | oai:repositorio.uam.es:10486/708878 |
| Acceso en línea: | http://hdl.handle.net/10486/708878 https://dx.doi.org/10.1016/j.jallcom.2019.152194 |
| Access Level: | acceso abierto |
| Palabra clave: | CaF2 nanoparticles Eu3+ Rietveld refinement Judd-Ofelt Concentration dependence Física |
| Sumario: | Eu3þ-doped CaF2 nanocubes with variable europium concentration, [Eu3þ] ¼ 0, 0.6, 1.3, 1.7, 2.2 and 5.4 mol%, have been synthesized by a direct precipitation route. It has been found that, within this concentration range, the nanoparticles present the fluoride-type crystalline structure and the characteristic cubic shape of CaF2 crystals. The nanoparticle size follows a log-normal distribution with a mean value decreasing with the Eu3þ content. Rietveld refinement has been performed to calculate the lattice parameter and crystallite size. Eu3þ concentration affects both parameters giving rise to an increase in the lattice parameter and a reduction of crystallite size. The luminescent properties of Eu3þ ions in these nanostructures have been investigated under CW and pulsed excitation. A Judd-Ofelt analysis, as function of the Eu3þ content, has been performed to determine the transition probabilities, radiative lifetimes and branching ratios of the 5D0 emitting level. It was found that U2 and U4 Judd-Ofelt intensity parameters are dependent on the doping level, showing an evolution that indicates a decrease in the Eu3þ site local symmetry with increasing Eu3þ concentration. Finally, it has been observed that the characteristic luminescence decay time of the 5D0 manifold is reduced with increasing Eu3þ concentration. This effect is partially due to an increase of radiative transition probability, associated with a reduction in the local symmetry of the lanthanide ions, and also to the occurrence of concentration quenching effects |
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