Effect of Annealing on Magnetic Properties of FePd and FePdPt Nanoparticles

Nanoparticles of FePd and FePdPt with the average size of similar to 3 nm have been prepared by modified polyol route. As-prepared nanoparticles are crystallized in fcc phase, whereas, 550-600 degrees C annealed nanoparticles are crystallized in fct phase. As-prepared samples are superparamagnetic at 300 K, whereas, annealed samples are strongly ferromagnetic at 300 K. As compared to fct FePd nanoparticles (He =1180 Oe), the fct FePdPt nanoparticles show significantly high coercivity (H-c = 4675 Oe) and squareness ratio (sigma(r)/sigma(s) =0.71) and thus, the addition of Pt in FePd nanoalloy improves the magnetic anisotropy significantly. The Curie temperature of FePd nanoalloy increases with increasing annealing temperature because of increase of atomic ordering in fct phase.