Size dependence on the ordering process in colloidal FePt nanoparticles

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

Journal of Applied Physics

American Institute of Physics

Año: 2007 vol. 101 p. 23903 - 23903

0021-8979

An alternative method to study the effects of annealing process on colloidal FePt nanoparticles
2–4 nm has been achieved. Annealing experiments at temperatures between 773 and 1073 K under inert atmosphere flux were performed in powder samples with excess of surfactant molecules on nanoparticle surface. Transmission electron microscopy, x-ray diffraction and magnetic measurements were performed to evidence the evolution of the chemically disordered fcc to chemically ordered face-centered tetragonal phase transformation. Magnetization measurements under zero-field-cooling and field-cooling
MZFC−MFC conditions, and hysteresis loops are extremely sensitive to the particle size distribution and were strongly affected by the annealing treatment