Luminescence study on Eu3+ doped Y2O3 nanoparticles:: particle size, concentration and core -: shell formation effects

Nanoparticles of Eu(3+) doped Y(2)O(3) (core) and Eu(3+) doped Y(2)O(3) covered with Y(2)O(3) shell (core -shell) are prepared by urea hydrolysis for 3 h in ethylene glycol medium at a relatively low temperature of 140 degrees C, followed by heating at 500 and 900 degrees C. Particle sizes determined from x-ray diffraction and transmission electron microscopic studies are 11 and 18 nm for 500 and 900. C heated samples respectively. Based on the luminescence studies of 500 and 900 degrees C heated samples, it is confirmed that there is no particle size effect on the peak positions of Eu(3+) emission, and optimum luminescence intensity is observed from the nanoparticles with a Eu(3+) concentration of 4-5 at.%. A luminescence study establishes that the Eu(3+) environment in amorphous Y(OH)(3) is different from that in crystalline Y(2)O(3). For a fixed concentration of Eu(3+) doping, there is a reduction in Eu(3+) emission intensity for core -shell nanoparticles compared to that of core nanoparticles, and this has been attributed to the concentration dilution effect. Energy transfer from the host to Eu(3+) increases with increase of crystallinity.