A new high Hcgamma ferric oxide exhibiting coercive force as high as 450-470 Oe

The basic properties of a new high H
c
gamma ferric oxide (γ-HY) exhibiting coercive force as high as 450 ∼ 470 Oe were compared with those of conventional gamma ferric oxide (γ-LOP). The average axial ratio was 9 : 1 and the average number of pores was 0.2 per one particle for γ-HY. The pigment volume concentration was 15% increased and the gloss of tape surface 25% improved for γ-HY in the same tape formulation. The squareness ratio was 8% larger and the switching field distribution 25% narrower for γ-HY. The improved dispersibility and orientability were directly observed from the scanning electron micrograph for γ-HY tape.