SYNTHESIS AND CHARACTERIZATION OF CHAINS COMPOSED OF NANOMETER-SIZE FE-CR-B PARTICLES

Ferromagnetic chains composed of nanometer size Fe-Cr-B particles have been synthesized by reducing a mixture of iron and chromium chloride solutions with potassium borohydride at ambient temperature in the pre sence of an applied magnetic field, The samples are characterized by i nductively coupled plasma analysis, transmission electron microscopy, X-ray diffraction and SQUID magnetometer measurements. The particle si ze could be varied from 28 to 60 nm by varying the ethanol content in the reaction medium. An increasing boron content with increasing ethan ol in the reaction medium causes a decrease in crystallinity, The obse rved magnetic properties are correlated to the degree of crystallinity , chemical composition and particle size. The magnetic properties are improved significantly by annealing the chains at 500 degrees C in Ar- H-2 mixture. The incorporation of about 1 at% Cr into the Fe-Cr-B chai ns enhances significantly the corrosion resistance. The magnetic data are also found to support the chain of spheres model for the magnetiza tion reversal.