The optical and magnetic properties of CeO2 nanoparticles doped with Er3+ions

The EPR spectroscopy and magnetization measurements were used to study the effect of annealing conditions on the local structure of Era+ ions in CeO2 : 1% Era+ nanoparticles. The nanoparticles were synthesized using the coprecipitation technique from an aqueous solution of cerium nitrate and hexamethylenetetramine. A correlation was found between the EPR spectra of the Era+ ions, magnetization and luminescence, depending on the annealing atmosphere, which proved the crucial role of oxygen vacancies in the origin of magnetism in CeO2 nanoparticles. EPR lines due to trigonal centers were clearly detected in CeO2 : 1% Era+ nanoparticles annealed in a vacuum, while no such lines were found for similar nanoparticles annealed under argon or air atmospheres.