Abstract
This paper reviews the developments of Ba ferrite particles and tape/flexible disk applications, which have been developed with expectation for use in perpendicular recording systems with readiness of media mass-production. Ba ferrite particles, produced by a glass crystallization method, features a narrow size distribution and the precise controllability of coercivity by the amount of Co-Ti substitution. 4 MB FDs/FDDs and Hi-8 VCR tapes were commercialized, but unfortunately they could not grasp the market popularity. Recently, finer Ba ferrite particles have been newly developed. They have more excellent recording capability than the old one, but at the same time they have posed thermal stability issue due to the smallness of the particle volume. The mean diameter of around 30 nm was concluded to be the best choice for the new Ba ferrite particles.
