Annealing Effects on 5 nm Iron Oxide Nanoparticles

VARGAS, J.; LIMA JR, E.; SOCOLOVSKY, L. M.; KNOBEL, M.; ZANCHET, D.; ZYSLER, R.

JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY

AMER SCIENTIFIC PUBLISHERS

Año: 2007 vol. 7 p. 1 - 5

1533-4880

Morphological, structural and magnetic properties of 4.8 nm iron oxide nanoparticles have beeninvestigated after annealing under inert atmosphere at different temperatures. The as-prepared ironoxide nanoparticles have been synthesized by chemical route from high temperature reaction ofFe(acac)3 solution in presence of oleic acid and oleylamine surfactant. Annealing the particles atlow temperatures (Tann = 573 K)produces an increment of the mean size from 4.8 nm to 6.0 nm,preserving the same morphology. The coercive field of the annealed sample has a small increasingwith respect to the as-prepared sample in agreement with the mean particle volume change.Annealing at higher temperature (Tann = 823 K)leads to a bimodal size distribution of the iron oxidenanoparticles with 6.0 nm and 17 nm mean sizes respectively, where the bigger particles dominatethe observed magnetic properties