Effect of switching field distributions and coercivity on magnetic recording properties

Two series of tapes were coated to investigate the effect of switching field distribution (SFD) and intrinsic coercivity (H
ci
) on audio recording properties. In the first series the concentration of γ-Fe
2
O
3
was varied by dilution with α-Fe
2
O
3
. The SFD, which increased with the amount of α-Fe
2
O
3
present, had a large effect on the linear recording range. Signal loss associated with SFD was separated from demagnetization loss. In the second series γ-Fe
2
O
3
was blended with different amounts of cobalt doped γ-Fe
2
O
3
in order to vary H
ci
. The ratio of short wavelength saturated output to sensitivity expressed in volts was proportional to H
ci
.