Patent ID: 8343577

Claim:
A method for preparing core-shell type nanoparticles, the method comprising the steps of: a) dispersing, in a mixed solvent of water and a first organic solvent, nanoparticle cores made of a material selected from the group consisting of the metals of Groups 3-15 of the periodic table, lanthanide metals, actinide metals, alloys of two or more of the metals, and semiconductor compounds; and b) dropping a metal oxide precursor dissolved in a second organic solvent into the solution prepared in step a), thereby forming core-shell type nanoparticles comprising shells made of crystalline metal oxide formed on the surfaces of the nanoparticle cores, wherein the rate of dropping in step b) is 5 μl/sec to 1 ml/sec per 100 mg of the nanoparticle cores.