250 mg of highest concentrated Eu3+ doped SiO2 nanoparticles were dispersed in 10 ml of ethanol.
After stirring until complete dissolution, y ml of the gold nanoparticles solution were added varying
y from 0.5 to 20 ml.
After stirring for 12 h at room temperature, the nanoparticles were then dried in an oven at 40 °C overnight. Fig. 1b presents a TEM picture of the Eu3+/Au co-doped SiO2 nanoparticle.
The TEM micrographs, representative of all the Au doped nanoparticles, show that the particle size of the gold nanoparticles is close to 4–5 nm.
As seen in the TEM micrographs, the gold nanoparticles are clearly adsorbed at the surface of the silica spheres.