Growth of Fe3O4 whiskers from solid solution nanoparticles of Fe-Cu and Fe-Ag systems produced by DC plasma jet method

Fe-Cu and Fe-Ag binary systems are virtually immiscible for a whole range of composition in equilibrium. In the present study, the nanoparticles of Fe-Cu and Fe-Ag systems were produced by direct current plasma jet method. These produced nanoparticles had mean particle sizes of about 70 run, and were a mixture of bcc and fcc phases. It was revealed by analytical high-resolution TEM observations that the nanoparticles of Fe-Cu and Fe-Ag systems were supersaturated solid solution. It has been found that numerous whiskers with a particle on their tip grow from these nanoparticles by heating above the temperature of 860 K under an Ar-O-2, atmosphere. The whiskers grow as the result of the phase separation in these solid solutions. The whiskers are composed of a Fe3O4 rod and a Cu2O particle on the tip. (C) 2002 Elsevier Science B.V. All rights reserved.