HIGH-COERCIVITY FE NANOPARTICLES PRODUCED BY COIMPLANTATION OF FE ANDC IN CU

A novel method was developed to prepare iron nanocrystallite by using coimplantation of Fe and C in copper and subsequent heat treatment. Th e formation process of iron carbide and iron granules was monitored by means of conversion-electron Mossbauer spectroscopy, and the particle size was determined by transmission electron microscopy. Cementite, F e3C, was formed after annealing at 300 degrees C, then transformed to alpha-Fe particles with a size of about 25 nm. Magnetic coercivities o f 1.15 kOe and 0.37 kOe for the Fe granules have been observed at room temperature (RT) and 80 K, respectively. A retained carbon-enhanced e ffect was proposed to explain the strong coercivity at RT.