One-pot synthesis and characterization of well defined core-shell structure of FePt@CdSe nanoparticles

Magnetic fluorescent FePt@CdSe core-shell nanoparticles were directly synthesized by sequential addition of precursors and using tetraethylene glycol as a solvent and a reducing agent. The core-shell NPs were successfully formed over a wide range of temperature (240-300 degrees C). The size and composition of the FePt core were tuned by changing the ratio of surfactant (oleic acid and oleylamine) to metal precursors [Fe(3)(CO)(12) and Pt(acac)(2)] and the feeding ratio of the precursors, respectively. The CdSe shell thickness also could be varied from 1 to 8.5 nm by rational control of the total amount of Cd and Se precursors. FePt@CdSe core-shell NPs with a core size of about 4.3 nm and shell thickness of about 2.5 nm displayed a fluorescence emission around 600 nm. They exhibited superparamagnetic behaviour at room temperature and the blocking temperature was about 55 K, which was almost the same as uncoated FePt NPs, while the coercivity decreased from 400 Oe for the FePt NPs to 200 Oe. Detailed characterization of intermediates and synthesized FePt@CdSe NPs revealed the fine structure and formation mechanism.