EPR of Ceria Nanoparticles Doped with Praseodymium and Terbium Ions

CeO₂ (ceria) nanoparticles doped with praseodymium and terbium were synthesized in two different ways, the CeO₂:Pr was prepared by the solid-state reaction at room temperature, and the CeO₂:Tb was prepared by co-precipitated method from aqueous solution. Electron paramagnetic spectroscopy was applied to study both types of ceria nanoparticles. It was found that praseodymium and terbium ions are mainly in a 3+ valence state, which means, they are non-Kramers ions. The charge compensators are most probably situated in the closest environment of rare earth ions. The most intensive line with g ∼1.97, detected in both types of samples, consists of two contributions, the typical line for CeO₂ nanoparticles and the line from the Gd³⁺ trace impurity, which has the same g-values.