Solution combustion synthesis, photoluminescence and X-ray luminescence of Eu-doped nanoceria CeO2:Eu

Abstract

Rare earth Eu³⁺-doped nanoceria with an average size of 60 nm were synthesized by urea–nitrate solution combustion reaction. The microstructure and morphology of the samples were characterized by X-ray diffraction patterns (XRD), X-ray photoelectron spectroscopy (XPS), and field emission scanning electron microscopy (SEM). The host is confirmed to be pure CeO₂. However, there are two distinct oxygen surroundings due to the substitution of Ce⁴⁺ species with Eu³⁺ ions. The optical properties of CeO₂:Eu were investigated by photoluminescence and X-ray luminescence spectroscopy. The samples can be excited with 360 nm (ultra-violet light, the charge transfer band of O–Ce) and 466 nm (blue light, the Eu^{3+ 7}F₀ → ⁵D₂ transition) respectively, and exhibit typical red-light emission of Eu³⁺. At low Eu³⁺ concentrations, the sample can be effectively excited with 360 nm. With the increase of the Eu³⁺ concentration, the dominant excitation wavelength is changed to 466 nm, which is beneficial for use in solid state lighting because of the coincidence with the emission of GaN chips. Under the excitation of 466 nm, the quenching concentration of Eu³⁺ can be increased to 16 mol% due to the interface effects of the nanoscale materials. Furthermore, the X-ray luminescence of CeO₂:Eu also shows strong red-light emission, manifesting that the material is a promising scintillator for radiation detection.