Patent Number: 6,251,474

Title: Method of producing substantially spherical magneto-plumbite ferrite particles

Abstract: Substantially spherical magneto-plumbite ferrite (barium or strontium ferrite) particles are formed from well-dispersed ultra-fine substantially spherical iron-based oxide and/or hydroxide particles as precursor particles. The precursor particles are mixed with a colloidal barium or strontium carbonate (BaCO.sub.3 or SrCO.sub.3), and with small amounts of a byproduct, such as sodium or potassium chloride (NaCl or KCl) or hydroxide (NaOH or KOH) or nitrate (NaNO.sub.3 or KNO.sub.3), functioning as a flux to lower the calcination temperature. The particles are filtered out of the mixture, dried, and calcined for a time sufficiently long and/or at a temperature sufficiently high to form magneto-plumbite ferrite from the precursor particles, and for a time sufficiently short and/or a temperature sufficiently low to maintain the general spherical shape of the precursor particles. The particles are used for forming a magnetic recording media by dispersing the particles in a magnetic paint and coating the paint onto a substrate, or by dispersing the particles in a self-supporting material.

Inventors: Hong; Yang-Ki (Moscow, ID), Jung; Hong Sik (Moscow, ID), Taylor; Patrick R. (Moscow, ID)

Assignee: Idaho Research Foundation

International Classification: H01F 1/032 (20060101); H01F 1/11 (20060101); B05D 005/12 ()

Expiration Date: 06/26/2018