Title :
Manipulation of temperature dependence of coercivity in isotropic nanocrystalline permanent magnets
Author :
Shigemoto, Y. ; Hirosawa, S.
Author_Institution :
Res. & Dev. Div., NEOMAX Co. Ltd., Osaka, Japan
Abstract :
The manipulation of the temperature dependence of coercivity, HcJ(T), in Nd-Fe-B-Ti-C-M (M = Ca, Sr, Bi and Ga) nanocrystalline permanent magnets by modifying the intergranular exchange coupling coefficients, Jeff, is obtained. Such HcJ manipulation is seen in a micromagnetic model describing the ratio of exchange energy and magnetocrystalline energy for a grain magnetically coupled to surrounding grains. The dependence of the absolute value of the temperature coefficient, alpha;(HcJ), between 296 K and 373 K on cooling rate is observed in annealed ribbons.
Keywords :
annealing; bismuth alloys; boron alloys; calcium alloys; coercive force; exchange interactions (electron); gallium alloys; grain boundaries; iron alloys; micromagnetics; nanostructured materials; neodymium alloys; permanent magnets; strontium alloys; titanium alloys; 296 to 373 K; NdFeBTiCBi; NdFeBTiCCa; NdFeBTiCGa; NdFeBTiCSr; annealing; coercivity; cooling rate; exchange energy; grains; intergranular exchange coupling coefficients; magnetocrystalline energy; micromagnetic model; nanocrystalline permanent magnets; temperature coefficient; Amorphous magnetic materials; Annealing; Bismuth; Coercive force; Magnetic anisotropy; Magnetic materials; Permanent magnets; Perpendicular magnetic anisotropy; Strontium; Temperature dependence;
Conference_Titel :
Magnetics Conference, 2005. INTERMAG Asia 2005. Digests of the IEEE International
Print_ISBN :
0-7803-9009-1
DOI :
10.1109/INTMAG.2005.1464259
