Sonochemical decomposition of Fe(CO)5 was carried out in the presence of different surfactants. The reactions give stable colloids of undecenoate, dodecyl sulfonate, and octyl phosphonate coated Fe2O3 nanoparticles of 5-16 nm in diameter. The ionic binding of the surfactants to the nanoparticle surfaces was confirmed by FTIR spectroscopy. Electron paramagnetic resonance measurements, magnetization curves, and zero-field cooled and field cooled studies indicate that the as-prepared amorphous nanoparticles are superparamagnetic. These studies show that the phosphonate-coated nanoparticles behave in a strikingly different manner from the other particles. It is proposed that the extra negative charge on the phosphonate, as compared to the carboxylate and sulfonate groups, makes it a strong bridging bidentate ligand, resulting in the formation of strong ionic bonds to the surface Fe3+ ions, which decreases the number of unpaired spins, possibly through a double superexchange mechanism through a Fe3+-O-P-O-Fe3+ pathway.
|Original language||English (US)|
|Number of pages||5|
|State||Published - Aug 7 2001|
ASJC Scopus subject areas
- Materials Science(all)
- Condensed Matter Physics
- Surfaces and Interfaces