Judd-ofelt analysis of Eu³⁺ emission in TiO₂ anatase nanoparticles

Preparation and spectroscopic studies of the TiO₂ nanopowders doped with Eu³⁺ ions are described. Efficient emission in the red part of the visible spectrum can be obtained due to the ⁵D₀→⁷F₂ emission of europium ions. Quantum efficiency of such emission was estimated to be about 0.83, which indicates a rather weak role of the non-radiative losses. However, the increase of Eu³⁺ concentration up to 10 at% significantly lowers the quantum efficiency because of the energy transfer and re-absorption processes. Higher doping concentrations (larger than 3 at% of Eu³⁺) also decrease the covalency of the Eu³⁺O^2- chemical bonds.