The effect of composition and structural ordering on the magnetism of FePt nanoparticles.
Spherical 4 nm FePt nanoparticles were synthesized by the simultaneous decomposition of Fe(CO)5 and the polyol reduction of Pt(acac)2. The final Fe-to-Pt composition was tuned between 15-55 at.% by varying the ingredient precursor ratios. The effect of composition and structural ordering on the macroscopic magnetic features of final FePt nanoparticles was examined via post-synthetic annealing stages at different conditions. Structural ordering is promoted in all cases, though samples approximating equiatomic Fe/Pt ratios eventually transform to fct-FePt phase while the FePt3-phase is favored for the Pt-richer samples. Consequently, the magnetic features of the annealed nanoparticles may be categorized; the hard magnetic FePt region dominating for Fe content between 40-55 at.% and the soft magnetic FePt3 region dominating in the region 20-30 at.% while Fe content less than 20 at.% results in Pt-richer phases with diminishing ferromagnetic behavior.
Department of Physics, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece.
O
O
Kalogirou
M
M
Angelakeris
C
C
Dendrinou-Samara
S
S
Mourdikoudis
K
K
Simeonidis
K
K
Gloystein
A
A
Vilalta-Clemente
I
I
Tsiaoussis