Relationships between magnetic tape properties and magnetic oxide concentration

A series of tapes were coated in which the concentration of the magnetic ferric oxide was essentially the sole variable. Magnetic and electroacoustic properties were evaluated as a function of magnetic oxide concentration. The intrinsic coercivity was found to increase slightly with decreasing oxide concentration but not to the extent predicted by the simple packing factor law. Biasing current changed in approximately the same ratio as coercivity. The sensitivity was directly proportional to the remanent flux density but the saturation output was proportional to the remanent flux. The linear range of the recording process increased appreciably with increasing oxide concentration. Frequency response decreased very slightly. Signal-to-noise ratio increased with increasing magnetic oxide concentration. Particle interactions had a strong effect upon the signal-to-print-through ratio. A decrease in magnetic oxide concentration to 50 percent of normal increased this ratio by 4 dB although coercivity was increased only slightly more than 5 percent.