Relationship of γ-Fe2O3audio tape properties to particle size

A series of γ-Fe2O3samples has been prepared and the relationship between particle size and magnetic and audio recording properties studied. The particles ranged in length and width from 0.4 and 0.06 μm, to 0.6 and 0.1 μm, respectively. This corresponds to a variation in calculated volume from 4 to 16 × 10^-4μm³. The magnetic and audio recording properties varied significantly with variation in particle size. Tape coercivity decreased from 319 to 241 Oe. Bias noise varied nearly linearly from -68 to -64 dB. Additional correlation of tape properties to particle size is also reported.