Title :
Magnetic properties of cobalt and cobalt-platinum alloy nanoparticles synthesized via microemulsion technique
Author :
Kumbhar, Amar ; Spinu, Leonard ; Agnoli, Fabrice ; Wang, Kai-Ying ; Zhou, Weilie ; O´Connor, Charles J.
Author_Institution :
AMRI, New Orleans, LA, USA
fDate :
7/1/2001 12:00:00 AM
Abstract :
Metallic cobalt and cobalt-platinum alloys of various nanometer sizes have been synthesized via the microemulsion technique and their magnetic properties have been characterized. Preparation of cobalt and cobalt-platinum alloy nanoparticles was achieved by reducing aqueous metallic salts confined in the polar regions of the reverse micelle of cetyltrimethyl bromide (CTAB) with sodium borohydride. These particles are further coated with gold by reducing aqueous gold salts with borohydride. The dc susceptibility data of 15 nm gold coated Co, CoPt and CoPt3 particles exhibit a blocking temperature of 4 K, 80 K and 106 K and coercivity of 20 Oe, 300 Oe, and 415 Oe at 10 K, respectively. Annealing these samples at 400°C further enhanced their magnetic properties. The two cobalt-platinum alloys have been synthesized and characterized by x-ray powder diffraction and transmission electron microscopy
Keywords :
X-ray diffraction; cobalt; cobalt alloys; coercive force; ferromagnetic materials; magnetic particles; magnetic susceptibility; materials preparation; microemulsions; nanostructured materials; particle size; platinum alloys; transmission electron microscopy; 10 K; 106 K; 15 nm; 4 K; 400 C; 80 K; Au; CTAB; Co; CoPt; CoPt3; annealing; aqueous metallic salts; blocking temperature; cetyltrimethyl bromide; cobalt nanoparticles; cobalt-platinum alloy nanoparticles; coercivity; dc susceptibility; gold; gold coated Co; gold coated CoPt; gold coated CoPt3; magnetic properties; microemulsion technique; nanometer size; reverse micelle; sodium borohydride; transmission electron microscopy; x-ray powder diffraction; Annealing; Cobalt alloys; Coercive force; Gold; Magnetic confinement; Magnetic properties; Nanoparticles; Powders; Temperature; X-ray diffraction;
Journal_Title :
Magnetics, IEEE Transactions on
