Estimate of the anisotropy field in isotropic SmCo 2:17 magnets with the Stoner-Wohlfarth CLC model

Microstructural changes during the slow-cooling annealing of nanocrystalline SmCo 2:17 type magnets

“…1 means that the nanocrystalline grains of 2:17 phase are well magnetic decoupled from each other. As above mentioned, in previous studies, the isotropic samples presented remanence equal or lower the half the saturation [10,11]. Remanence lower than half the saturation may be caused by magnetostatic coupling [16].…”

“…H is the applied field, H A is the anisotropy field, M is magnetization and M S is the magnetization of saturation and (1/d) is the CLC particle interaction parameter [10,11]. h SW refers to the isotropic hysteresis presented by Stoner and Wohlfarth for phases with uniaxial anisotropy [15].…”

“…h SW refers to the isotropic hysteresis presented by Stoner and Wohlfarth for phases with uniaxial anisotropy [15]. In previous studies, it was found that (1/d) parameter is always positive [10,11], and this implies that the observed remanence was less than the half of saturation (M S ) predicted by the original SW model [15]. Fig.…”

“…The microstructural changes during the last annealing steps (iii) and (iv) are re-evaluated in the present study using Rietveld analysis of X-ray Diffraction data, SEM (scanning electron microscope)-FEG (field emission gun) images, and also with modeling of the hysteresis curves with the Stoner-Wohlfarth-Callen-Liu-Cullen (SW-CLC) model [10][11][12][13], which gives relevant information concerning coercivity mechanisms. It is also employed a diffusion-based microstructural model able to make helpful predictions concerning change of chemical composition of the nanocrystalline phases along the heat treatment [14].…”

“…These possible interactions maybe either exchange coupling or magnetostastic coupling. The CLC modification changes the shape of the hysteresis curve similarly to an inverse demagnetizing field [10,11]. submitted to (i) a solubilization heat treatment at 1175°C for 4 h, (ii) quenching in water, (iii) reheated up to 820°C, remaining at this temperature for 7 h, and (iii) were then slow cooled (À1°C/min) to 400°C, and remaining for an additional 24 h at 400°C.…”