Luminescent aerogels of Gd₂O₃:Eu³⁺ and Gd₂O₃:(Eu³⁺, Tb³⁺)

This study reports on the fabrication and characterization of luminescent aerogels of Gd₂O₃:Eu³⁺ and Gd₂O₃:(Eu³⁺, Tb³⁺), synthetized by the sol–gel method and the supercritical drying technique. The mol% concentration of the Eu³⁺ and Tb³⁺ ions in the synthesis were varied to study the effects of concentration on the luminescent properties of the aerogels. The results show that the Gd₂O₃:Eu³⁺ and the Gd₂O₃:(Eu³⁺, Tb³⁺) aerogels exhibited a maximum emission at λ = 613 nm. For all the samples, a decay in light intensity occurred when a concentration of 8 mol% of Eu³⁺ was exceeded, regardless of whether the Tb³⁺ ion was present. The analysis by X-ray diffraction showed that the aerogels of Gd₂O₃:Eu³⁺, like those of Gd₂O₃:(Eu³⁺, Tb³⁺), had a cubic crystalline structure with no change even at high concentrations of Eu³⁺. The microscopy analyses showed that the aerogels present a porous structure made up of interconnected quasi-spherical nanoparticles that formed a three-dimensional network. Quantum yield analysis shows that Tb³⁺ acts as a sensitizer of Eu³⁺, increasing the light intensity in the aerogels. The results reveal that it is possible to manufacture luminescent aerogels of rare-earth oxides that can be used in opto-electronic devices.