Rare-earth-free or iron-based permanent nanomagnets are emerging as promising candidates
for energy-conversion and information technologies. In this interest, FexPd100-x nanoparticles
(x = 50, 55, 60, and 63) were prepared from iron acetate and palladium acetate by
sonoelectrodeposition. After annealing the nanoparticles at various temperatures from
450 to 700 °C for 1 h, structural changes were observed, and the samples exhibit hard
magnetic properties that depend strongly on chemical composition and annealing temperature.
The major phase in the as-prepared nanoparticles has a disordered face-centered cubic
structure, which, upon annealing, transforms into a multi-phase material containing
a L10 ordered FePd phase. The fractions of different phases present in the annealed
samples, including that of the L10 phase as functions of chemical composition and
annealing temperature, are quantified by means of X-ray diffraction and scanning transmission
electron microscopy. Magnetic measurements show the desirable hard magnetic properties
for the samples annealed at 550–600 °C. A correlation between the magnetic coercivity
and the L10 ordered FePd phase fraction is established for the first time in the FexPd100-x
nanoparticles.
