Magnetic Viscosity and Magnetization Reversal of Acicular Barium Ferrite Particles

抄録

  The magnetic viscosity coefficient (Sv), the activation volume (Vact), the rotational hysteresis integral (Rh) and the average anisotropy field (H_A,ave) were examined for acicular BaCo_xTi_xFe_12-2xO₁₉ (x=0-1.0) particles prepared by a conventional sintering method. Acicular hexagonal Ba-ferrite particles with different coercive force (Hcj=35-310 MA/m) were prepared, and the dependence of Vact, Rh and H_A,ave on Hcj was investigated. The results show that Hcj is proportional to Vact^−2.2, as in the case of the platelet Ba-ferrite particles, SrM particles, SrW and Sm₂Fe₁₇N_x magnets, which all have a similar mechanism of magnetization reversal. Also, H_A,ave increases with increasing Hcj and Vact is inversely proportion to the average anisotropy constant. It was found that Rh and Vact both decrease, as Hcj increases, to approach the coherent rotation mode.