Comparative Measurements of the Effective Anisotropy Field Ha for Barium Ferrites

摘要: Abstract BaFe12O19 powders were prepared by coprecipitation and glass crystallization. Electron microscopic investigations revealed that the particles of crystallized powder exhibit excellent uniform shapes narrow size distribution in comparison to coprecipitated one consisting irregularly shaped, polycrystalline with a broad inhomogeneous distribution. The crystallites particles, however, are smaller (mean diameter D = 0.11 μm) is narrower than mean 0.42 μm. lattice perfection both ensembles quite good. In order determine magnetic properties — above all effective anisotropy field we used six different methods: transverse susceptibility χt, singular point detection (SPD), ferromagnetic resonance (FMR), torsion pendulum (TP), rotational hysteresis losses (RHL), remanence curves (RC). It has been found differences coercivity values HcJ not dramatic (about ±3%). Effective fields Ha measured “switching” methods (RHL, RC) those “stiffness” ones (FMR, TP, SPD, χt), about 1700 Oe for 2500 one. particle assemblies present do pure Stoner-Wohlfarth behaviour, because their relatively large diameters. ratio HcJ/Ha ≈ 0.39 near ideal value 0.48, although considerably mechanically aggregated.