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 (Hci) on audio recording properties. In the first series the concentration of γ-Fe2O3was varied by dilution with α-Fe2O3. The SFD, which increased with the amount of α-Fe2O3present, had a large effect on the linear recording range. Signal loss associated with SFD was separated from demagnetization loss. In the second series γ-Fe2O3was blended with different amounts of cobalt doped γ-Fe2O3in order to vary Hci. The ratio of short wavelength saturated output to sensitivity expressed in volts was proportional to Hci.