Preparation and magnetic properties of nanosized amorphous ternary Fe-Ni-Co alloy powders

Nanosized amorphous alloy powders of Fe25Ni13Co62, Fe38Ni23Co39, Fe-40,Ni-2 4,Co-36, and Fe69Ni9Co22 were prepared by sonochemical decomposition of sol utions of volatile organic precursors, Fe(CO)(5), Ni(CO)(4), and Co(NO)(CO) (3) in decalin, under an argon pressure of 100 to 150 kPa at 273 K. The amo rphous nature of these particles was confirmed by various techniques, such as scanning electron microscopy, transmission electron microscopy, electron microdiffraction, and x-ray diffractograms. Magnetic measurements indicate d that the as-prepared amorphous Fe-Ni-Co alloy particles were superparamag netic. The observed magnetization measured up to a field of 1.5 kG of the a nnealed Fe-Ni-Co samples (75-87 emu g(-1)) was significantly lower than tha t for the reported multidomain bulk particles (175 emu g(-1)), reflecting t he ultrafine nature of our sample.