Particle Size Control of Y_2O_3:Eu~(3+) Prepared via a Coconut Water-Assisted Sol-Gel Method

摘要

Eu~(3+) -doped Y_2O_3 nanoparticles were produced through proteic sol-gel technique, and the adjustment of pH was tested in order to control the particle size of the powders. A strong correlation between the initial pH and the temperature of crystallization was observed, allowing the production of particles with controlled diameter from 4 nm to 50 nm. The samples were characterized by X-ray diffraction, high-resolution transmission electron microscopy, optical microscopy and photoluminescence spectroscopy in both absorption and emission modes. A blue shift of the excitation peak corresponding to energy transfer from Y_2O_3:Eu~(3+)host to Eu" ions was observed, as the particle size was reduced from 50 to 4 nm. The suppression of a charge transfer band also resulted from the reduction of the particle size. The emission spectrum of the Y203: with particles of 50 nm was found to be similar to that of bulk material whereas 4 nm particles presented broadened emission peaks with lower intensities.