Effects of the Addition of Barium Chloride as a Flux and the Grind with a Planetary Ball Mill on the Synthesis of Barium Ferrite for Magnetic Recording

Abstract

The addition of flux and the grind of calcined powders in the synthesis of barium ferrite for use in magnetic recording have been examined to improve the reaction efficiency. In this study, barium chloride was entirely used as the flux. In the absence of the flux, the synthesis reaction of barium ferrite was practically completed at 1130 °C and for 70 min, but the coercive force of the product did not fit the Cybernetics standard. In the presence of barium chloride in a range between 1.9 and 2.9%, however, the synthesis reaction reached near completion (97.1%) and the coercive force of the product (2510—2620 Oe) fitted the Cybernetics standard. Furthermore, the coercive force of the samples, which had been below the Cybernetics standard at the calcination stage, was much improved by grinding the calcined powders with a planetary ball mill, and the distribution of coercive force, i.e., SFD (switching field distribution) were successfully kept down to the level required for practical use. © 1997, The Chemical Society of Japan. All rights reserved.