Iron Acicular Particles in Metal Audio Tapes.

The lattice constant (a0), crystallite size (d) and the crystallite orientation of a-Fe acicular particles in commerciallyavailable audio metal tapes were studied using x-ray diffraction. The value of a0 is determined to be 0.28669 ± 0.00005 nm, which is slightly larger than that of pure Fe. The reason of the small discrepancy of a0 was estimated to be due to 0.1 at%-Al addition into Fe. The acicular particle consists of many crystallite: the crystallite sizes along long axis of acicular particle (22 nm) is larger than the short axis (14 nm). The tendency that the [100] axis of Fe crystallite aligns with the long axis of the acicular particle is observed.