Title :
Compositionally controlled FePt nanoparticle materials
Author :
Sun, Shouheng ; Fullerton, Eric E. ; Weller, Dieter ; Murray, C.B.
Author_Institution :
IBM Thomas J. Watson Res. Center, Yorktown Heights, NY, USA
fDate :
7/1/2001 12:00:00 AM
Abstract :
High temperature solution phase decomposition of Fe(CO)5 and reduction of Pt(acac)2 in the presence of stabilizers, oleic acid and oleyl amine, are employed to produce 4 nm diameter FePt nanoparticles. The Fe and Pt composition of the nanoparticle materials can be tuned by adjusting the molar ratio of Fe(CO)5 to Pt(acac)2, and the compositions ranging from Fe30Pt70 to Fe80Pt20 are obtained. The nanoparticle materials are easily dispersed into alkane solvent, facilitating their self-organization into nanoparticle superlattices. As synthesized FePt nanoparticles possess a disordered fcc structure and show superparamagnetic behavior. Thermal annealing induces a change of internal particle structure and thus of the magnetic properties of the particles. Composition dependent structure analysis shows that an annealed FePt nanoparticle assembly with a composition around Fe55Pt45 will lead to the highly ordered fct phase. This Fe55Pt45 nanoparticle assembly yields high coercivity, and will be a candidate for future ultra-high density magnetic recording media applications
Keywords :
annealing; coercive force; ferromagnetic materials; iron alloys; magnetic hysteresis; magnetic particles; magnetic recording; nanostructured materials; platinum alloys; self-assembly; superparamagnetism; 4 nm; Fe30Pt70; Fe55Pt45; Fe80Pt20; FePt; alkane solvent; coercivity; compositionally controlled FePt nanoparticle materials; disordered fcc structure; high temperature solution phase decomposition; highly ordered fct phase; internal particle structure; magnetic properties; molar ratio; nanoparticle superlattices; oleic acid; oleyl amine; reduction; self-organization; superparamagnetic behavior; thermal annealing; ultra-high density magnetic recording media; Annealing; Assembly; Composite materials; Iron; Magnetic materials; Magnetic superlattices; Nanoparticles; Nanostructured materials; Solvents; Temperature;
Journal_Title :
Magnetics, IEEE Transactions on
