New experimental and theoretical approach in Eu2O3 microspheres: From synthesis to a study of the energy transfer

We have prepared porous microspheres of Eu2O3 using a simple, two-step procedure. In the first step, hydrothermal conditions were used to prepare the precursor spheres from EuCl3·6H2O and 6-aminonicotinic acid. Then, a heat treatment under inert atmosphere yielded the final material. Its structure and purity were confirmed by XRD, while SEM images showed the widespread spherical morphology. Excitation and emission spectra allowed us to infer details about the local symmetry of the Eu3+ and correlate them with what is known from the oxide. In addition, the Eu2O3 structure was accurately predicted for the first time by applying the combination of the Sparkle/PM3 model with a semiempirical approach to simulate solid state structures to a set containing more than 600 atoms. The full optimized structure was used to study the energy transfer channels between two europium trivalent ions. The results suggest that the Eu3+ ⟶ Eu3+ energy transfer channels herein investigated are predominantly governed by quadrupole–quadrupole mechanism.