Microwave assisted synthesis of monodispersed Y2O3 and Y2O3:Eu3+ particles

Monodisperse spherical Y2O3 and Y2O3:Eu3+ nanocrystalline particles with particle size between 100 nm and 350 nm were successfully prepared by microwave assisted urea precipitation method followed by a thermochemical treatment. Fast microwave heating, controlled decomposition of urea and burst nucleation of metal ions in aqueous solution led to the formation of non-aggregated spherical particles with narrow size dispersion. The particle size and size dispersion was controlled by adjusting the urea/metal ions ratio, the metal ions concentration, the reaction time and the temperature. X-ray diffraction (XRD) analysis indicated that the as prepared particles have Y(OH)CO3 composition, which converted to highly crystalline cubic Y2O3 after calcination at temperatures above 600 °C. The calcined Y2O3 particles preserved the spherical morphology of the as prepared particles and exhibited polycrystalline structure. The size of the crystallites increased from ~8 nm to ~37 nm with the increase of the calcination temperature from 500 °C to 900 °C. In order to transform these nanostructures to luminescent composition, Eu3+ doping has been performed. Y2O3:Eu3+ particles inherited the morphology and polycrystalline structure of the host Y2O3 particles. Photoluminescence (PL) analysis of Y2O3:Eu3+ particles showed a strong red emission peak at 613 nm corresponding to 5D0–7F2 forced electric dipole transition of Eu3+ ions under UV excitation. All these critical characteristics, and being heavy-metal free, make these particles useful for bioimaging, and display devices.