Sol-gel synthesis of Eu ³⁺, Tb ³⁺ co-doped Y ₂0 ₃ scintillating nanopowders

Y ₂O ₃:Eu ³⁺, Tb ³⁺ nanopowders were prepared via the sol- gel process, using yttrium pentadionate, europium, terbium nitrates, and ethanol as precursors. After the sol evaporation at 100 °C, the formed gel was annealed from 300 to 900 °C for 15min, and the obtained nanopowders were analyzed by X-ray diffraction to characterize the microstructural behavior and the crystalline structure, which was determined as mainly cubic. The crystallite size varies from 8.6 to 30.9 nm, at 500 and 900 °C, respectively. Transmission electron microscopy studies were carried out in order to analyze the microstructure and the size of crystallites. Three different Tb ³⁺ atomic contents (0.005, 0.075, and 0.01 at.%) were used at a fixed Eu ³⁺ level (2.5 at.%) with the aim of determining the relationship between the co-doping content and the scintillation intensity of the well-known ⁵D ₀→ ⁷F ₂ europium emission band at 611 nm. The results show that at higher Tb ³⁺ contents, a quenching process occurs between Eu ³⁺ and Tb ³⁺; however, even with the lowest Tb ³⁺ content (0.005 at.%), an increment on the scintillation light yield is observed compared with a Eu ³⁺ monodoped sample.