Particle size tailoring and luminescence of europium(III)-doped gadolinium oxide obtained by the modified homogeneous precipitation method: Dielectric constant and counter anion effects

This work reports on controlling the particle size distribution of europium(III)-doped gadolinium oxide samples prepared through a topochemical reaction carried out by thermal treatment of europium(III)-doped gadolinium hydroxycarbonate. Hydroxycarbonate samples were obtained by a modified homogeneous precipitation method using different solvent mixtures, such as water:ethanol, water:ethylene glycol, water:tert-butanol, and different counter ions such as nitrate and chloride. The luminescent properties of the oxide samples, are characteristics of europium(III) ions, with the hypersensitive transition (5D0 → 7F2) being the most intense emission peak and the emission lifetime values are typical for this system. The spherical particle size distribution of europium(III)-doped gadolinium oxide can be tailored by selecting the counter anion types, the chemical nature of the alcohol and the dielectric constant of the reaction media. The appropriate control of these parameters allows the preparation of rare-earth doped gadolinium samples having monomodal particle size distributions with mean sizes between 30 and 90 nanometers.