Progress in recording materials: A critical review

In the past 5-7 years, the field of magnetic materials for tape and disc manufacturing, called for a striking amount of research in order to keep up with the hardware developement and the increasing competition among tape producers. These researches yielded a remarkable increase in quality of materials and a shift in the powder consumption towards the high quality powders although the bulk of the world consumption is still kept by the so-called "low noise materials". Densification and increase in acicularity and homogeneity of γ-Fe2O3, double layer tapes,new high coercivity CPO2, new epitaxially cobalt doped iron oxides, non stoichiometric γ-Fe2O3and different types of Co-doped materials are the major advances. Such advances are easily understood bearing in mind some well known models for the recording and reproduction process. Further advances in materials and in understanding the involved phenomena are possible if magneticians will look into other fields of sciance, such as the chemistry of monodispersed systems and new techniques of size and shape evaluation, in order to get a better picture of the whole field.