Red and near-infrared emitting phosphors based on Eu3+- or Nd3+-doped lanthanum niobates prepared by the sol-gel route

Autor(es)

Manfre, Mateus Grecco ; Labaki, Hayra do Prado ; de Souza, Vitor dos Santos ; Goncalves, Rogeria R.

• Tipo de documento: Artigo Científico
• Fonte: DALTON TRANSACTIONS; v. 51, n. 46, p. 14-pg., 2022-10-31.

Resumo

We have evaluated the structural and luminescence properties of Eu3+- or Nd3+-doped lanthanum niobate systems synthesized via a sol-gel route and containing different dopant contents. XRD analysis revealed that the orthorhombic La3NbO7 and monoclinic LaNbO4 crystalline phases were present in all the samples, regardless of the dopant concentration. The excitation spectra of the samples displayed a broad band due to Nb -> 5+O2- charge transfer; this band was quite sensitive to the increasing Eu3+ content. The photoluminescence emission spectra of the samples with a lower Eu3+ content showed that Eu3+ occupied both crystalline phases. However, when the Eu3+ content increased, these ions preferentially occupied the C-2 symmetry sites in the LaNbO4 host lattice. There was no emission quenching for the Eu3+- doped samples with a Eu3+ content as high as 20 mol%. The emission spectra of the Nd(3+)doped samples displayed an intense emission band in the NIR-II biological window under NIR-I excitation, at 808 nm. In the case of the samples with a lower Nd3+ content, Nd3+ occupied distinct symmetry sites in La3NbO7. In contrast, in the samples with a higher Nd3+ content, these ions preferentially occupied LaNbO4 sites. The Nd3+ concentration that quenched emission in the Nd3+-doped samples was about 2.6 mol%, due to Nd3+-Nd3+ cross-relaxation processes. On the basis of these findings, the Eu3+-doped samples explored herein have promising applications in the lighting field, whereas the Nd3+- doped samples have potential use as solid-state lasers and biomarkers. (AU)

• Processo FAPESP: 21/08111-2 - Materiais conversores de luz à base de terras raras: marcadores luminescentes, sensores e amplificadores ópticos
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