Influence of zinc on cobalt substituted magnetic recording media

The instability of magnetic properties of cobalt substituted acicular iron oxides can be reduced without losing the desirable properties in their application as high energy magnetic recording media. It is shown that by introducing small amounts of zinc into these oxides, they become chemically and magnetically stable. This stabilizing effect is produced by the ability of zinc to decrease the crystal anisotropy of the cobalt substituted iron oxides. The degree of chemical stability and the degree of magnetic stability is dependent not only on the zinc content but also on the zinc to cobalt ratio. In addition, tapes prepared from these powders do not show magnetostrictive losses under pressure, as is the case with cobalt substituted iron oxides.