F-127-Assisted Sol-Gel Synthesis of Gd₂O₃:Eu³⁺ Powders and Films

In the current work, the influence of Pluronic F-127 (S = F-127) and temperature on the luminescent properties of Gd₂O₃:Eu³⁺ (Gd:S = 1:2) powders and films was studied. In order to synthesize the powders and films (by the dip-coating technique), Gd₂O₃: Eu³⁺ (5 mol%) ceramics were elaborated by the sol-gel route, using gadolinium and europium nitrates as precursors. The results obtained by means of X-ray diffraction, confirmed the presence of the cubic structure of Gd₂O₃ (in 800 ºC heat-treated powders and 700 ºC heat-treated films), and crystals with nanometer sizes of ~19 nm, and ~15 nm, corresponding to the spherical and laminar-like morphologies of densified powders and films, respectively. Crystallites from the cubic and monoclinic structure were present on Gd₂O₃: Eu³⁺-modified films up to 800 ºC. Chemical identification of the bonds present in the films was performed by Fourier transform infrared spectroscopy, which identified representative infrared absorption at 543 cm^-1, attributable to the Gd-O vibration. Photoluminescence studies showed that when the powders and films were heat-treated at 800 ºC, the intensity of their luminescence at the ⁵D₀→⁷F₂ Eu³⁺ transition (618 nm) was enhanced by the presence of F-127.

Keywords:
Gd₂O₃; Pluronic F-127; sol-gel; powders; films; europium