Magnetic Properties of Single-Domain Iron and Iron-Cobalt Particles Prepared by Borohydride Reduction

Air-stable, single-domain Fe and Fe-Co particles prepared by the reaction of the metal salts with aqueous borohydride have higher coercivities and axial ratios if prepared in a magnetic field. Oxide and boride impurities are indicated by elemental analyses and lowered saturation magnetizations. Studies of coercivitiesand magnetizations as a function of temperature, remanence ratios, and rotational hysteresis measurements indicate single-domain behavior with coercivity controlled by shape and somewhat by crystalline anisotropy in approximate agreement with the predictions of the Jacobs-Bean “chain of spheres” model.