Patent ID: 6251474
Filing Date: 2001-06-26
Classification: G11B,H01F,Y10S,Y10T

Abstract:
A process for the preparation of a spherical magneto-plumbite ferrite powder having the formula AO.n(Fe.sub.2-x M.sub.x O.sub.3), wherein A is at least one of barium and strontium, n is the molar (Fe.sub.2-x M.sub.x O.sub.3)/AO ratio in the range of about 5 to about 6, M is more than one substitution element selected from the group of Co, Zn, Ni, Al, Ti, Sn, Si, Nb, Ta, and mixtures thereof, and x is the content of substitution elements in the range of about 0 to about 3.5, the process comprising:(a) mixing a dispersion of precursor substantially spherical particles, of one or more of iron-based oxide and iron hydroxide, with a first solution of one or more of barium and strontium, and with a second solution of one or more of Na.sub.2 CO.sub.3, K.sub.2 CO.sub.3, NaOH, and KOH;(b) separating a solid phase from the dispersion;(c) drying the separated solid phase; and(d) calcining the dried separated solid phase at a temperature sufficiently low to produce magneto-plumbite particles from the precursor particles while preserving the substantially spherical shape of the precursor particles.