EFFECT OF SURFACE-PROPERTIES ON COBALT MODIFICATION OF IRON-OXIDES

Cobalt-modified iron oxides have been consistently improved in recent years, but the factors determining the effectiveness of the cobalt doping process are still not well understood. In this study nine different gamma Fe2O3 samples were surface modified with Fe2+ and Co2+ ions. The coercivity (H(C)), the specific surface area (SSA), and the acid-base characteristics of the core particles were measured, as well as the coercivity of the final product. A relationship was found between the integral surface charge density (ISCD) of the core particles and the surface efficiency defined as the difference between the final and the initial Hc normalized by the SSA at a constant amount of Fe2+ and Co2+. The technological importance of this finding is that the efficiency of the cobalt doping process can be related to measurable surface properties of the core particles.